includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * This file deals with database interface functions
   6  * and query specifics/optimisations.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup Database
  25  */
  26
  27 /**
  28  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  29  * following must be implemented to support MediaWiki
  30  *
  31  * @file
  32  * @ingroup Database
  33  */
  34 interface DatabaseType {
  35         /**
  36          * Get the type of the DBMS, as it appears in $wgDBtype.
  37          *
  38          * @return string
  39          */
  40         function getType();
  41
  42         /**
  43          * Open a connection to the database. Usually aborts on failure
  44          *
  45          * @param string $server database server host
  46          * @param string $user database user name
  47          * @param string $password database user password
  48          * @param string $dbName database name
  49          * @return bool
  50          * @throws DBConnectionError
  51          */
  52         function open( $server, $user, $password, $dbName );
  53
  54         /**
  55          * Fetch the next row from the given result object, in object form.
  56          * Fields can be retrieved with $row->fieldname, with fields acting like
  57          * member variables.
  58          * If no more rows are available, false is returned.
  59          *
  60          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  61          * @return object|bool
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchObject( $res );
  65
  66         /**
  67          * Fetch the next row from the given result object, in associative array
  68          * form.  Fields are retrieved with $row['fieldname'].
  69          * If no more rows are available, false is returned.
  70          *
  71          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  72          * @return array|bool
  73          * @throws DBUnexpectedError Thrown if the database returns an error
  74          */
  75         function fetchRow( $res );
  76
  77         /**
  78          * Get the number of rows in a result object
  79          *
  80          * @param $res Mixed: A SQL result
  81          * @return int
  82          */
  83         function numRows( $res );
  84
  85         /**
  86          * Get the number of fields in a result object
  87          * @see http://www.php.net/mysql_num_fields
  88          *
  89          * @param $res Mixed: A SQL result
  90          * @return int
  91          */
  92         function numFields( $res );
  93
  94         /**
  95          * Get a field name in a result object
  96          * @see http://www.php.net/mysql_field_name
  97          *
  98          * @param $res Mixed: A SQL result
  99          * @param $n Integer
 100          * @return string
 101          */
 102         function fieldName( $res, $n );
 103
 104         /**
 105          * Get the inserted value of an auto-increment row
 106          *
 107          * The value inserted should be fetched from nextSequenceValue()
 108          *
 109          * Example:
 110          * $id = $dbw->nextSequenceValue( 'page_page_id_seq' );
 111          * $dbw->insert( 'page', array( 'page_id' => $id ) );
 112          * $id = $dbw->insertId();
 113          *
 114          * @return int
 115          */
 116         function insertId();
 117
 118         /**
 119          * Change the position of the cursor in a result object
 120          * @see http://www.php.net/mysql_data_seek
 121          *
 122          * @param $res Mixed: A SQL result
 123          * @param $row Mixed: Either MySQL row or ResultWrapper
 124          */
 125         function dataSeek( $res, $row );
 126
 127         /**
 128          * Get the last error number
 129          * @see http://www.php.net/mysql_errno
 130          *
 131          * @return int
 132          */
 133         function lastErrno();
 134
 135         /**
 136          * Get a description of the last error
 137          * @see http://www.php.net/mysql_error
 138          *
 139          * @return string
 140          */
 141         function lastError();
 142
 143         /**
 144          * mysql_fetch_field() wrapper
 145          * Returns false if the field doesn't exist
 146          *
 147          * @param string $table table name
 148          * @param string $field field name
 149          *
 150          * @return Field
 151          */
 152         function fieldInfo( $table, $field );
 153
 154         /**
 155          * Get information about an index into an object
 156          * @param string $table Table name
 157          * @param string $index Index name
 158          * @param string $fname Calling function name
 159          * @return Mixed: Database-specific index description class or false if the index does not exist
 160          */
 161         function indexInfo( $table, $index, $fname = __METHOD__ );
 162
 163         /**
 164          * Get the number of rows affected by the last write query
 165          * @see http://www.php.net/mysql_affected_rows
 166          *
 167          * @return int
 168          */
 169         function affectedRows();
 170
 171         /**
 172          * Wrapper for addslashes()
 173          *
 174          * @param string $s to be slashed.
 175          * @return string: slashed string.
 176          */
 177         function strencode( $s );
 178
 179         /**
 180          * Returns a wikitext link to the DB's website, e.g.,
 181          *     return "[http://www.mysql.com/ MySQL]";
 182          * Should at least contain plain text, if for some reason
 183          * your database has no website.
 184          *
 185          * @return string: wikitext of a link to the server software's web site
 186          */
 187         function getSoftwareLink();
 188
 189         /**
 190          * A string describing the current software version, like from
 191          * mysql_get_server_info().
 192          *
 193          * @return string: Version information from the database server.
 194          */
 195         function getServerVersion();
 196
 197         /**
 198          * A string describing the current software version, and possibly
 199          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 200          * Use getServerVersion() to get machine-friendly information.
 201          *
 202          * @return string: Version information from the database server
 203          */
 204         function getServerInfo();
 205 }
 206
 207 /**
 208  * Interface for classes that implement or wrap DatabaseBase
 209  * @ingroup Database
 210  */
 211 interface IDatabase {
 212 }
 213
 214 /**
 215  * Database abstraction object
 216  * @ingroup Database
 217  */
 218 abstract class DatabaseBase implements IDatabase, DatabaseType {
 219         /** Number of times to re-try an operation in case of deadlock */
 220         const DEADLOCK_TRIES = 4;
 221         /** Minimum time to wait before retry, in microseconds */
 222         const DEADLOCK_DELAY_MIN = 500000;
 223         /** Maximum time to wait before retry */
 224         const DEADLOCK_DELAY_MAX = 1500000;
 225
 226 # ------------------------------------------------------------------------------
 227 # Variables
 228 # ------------------------------------------------------------------------------
 229
 230         protected $mLastQuery = '';
 231         protected $mDoneWrites = false;
 232         protected $mPHPError = false;
 233
 234         protected $mServer, $mUser, $mPassword, $mDBname;
 235
 236         protected $mConn = null;
 237         protected $mOpened = false;
 238
 239         /** @var callable[] */
 240         protected $mTrxIdleCallbacks = array();
 241         /** @var callable[] */
 242         protected $mTrxPreCommitCallbacks = array();
 243
 244         protected $mTablePrefix;
 245         protected $mFlags;
 246         protected $mForeign;
 247         protected $mErrorCount = 0;
 248         protected $mLBInfo = array();
 249         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 250         protected $mDefaultBigSelects = null;
 251         protected $mSchemaVars = false;
 252
 253         protected $preparedArgs;
 254
 255         protected $htmlErrors;
 256
 257         protected $delimiter = ';';
 258
 259         /**
 260          * Either 1 if a transaction is active or 0 otherwise.
 261          * The other Trx fields may not be meaningfull if this is 0.
 262          *
 263          * @var int
 264          */
 265         protected $mTrxLevel = 0;
 266
 267         /**
 268          * Remembers the function name given for starting the most recent transaction via begin().
 269          * Used to provide additional context for error reporting.
 270          *
 271          * @var String
 272          * @see DatabaseBase::mTrxLevel
 273          */
 274         private $mTrxFname = null;
 275
 276         /**
 277          * Record if possible write queries were done in the last transaction started
 278          *
 279          * @var Bool
 280          * @see DatabaseBase::mTrxLevel
 281          */
 282         private $mTrxDoneWrites = false;
 283
 284         /**
 285          * Record if the current transaction was started implicitly due to DBO_TRX being set.
 286          *
 287          * @var Bool
 288          * @see DatabaseBase::mTrxLevel
 289          */
 290         private $mTrxAutomatic = false;
 291
 292         /**
 293          * Array of levels of atomicity within transactions
 294          *
 295          * @var SplStack
 296          */
 297         private $mTrxAtomicLevels;
 298
 299         /**
 300          * Record if the current transaction was started implicitly by DatabaseBase::startAtomic
 301          *
 302          * @var Bool
 303          */
 304         private $mTrxAutomaticAtomic = false;
 305
 306         /**
 307          * @since 1.21
 308          * @var file handle for upgrade
 309          */
 310         protected $fileHandle = null;
 311
 312         /**
 313          * @since 1.22
 314          * @var Process cache of VIEWs names in the database
 315          */
 316         protected $allViews = null;
 317
 318 # ------------------------------------------------------------------------------
 319 # Accessors
 320 # ------------------------------------------------------------------------------
 321         # These optionally set a variable and return the previous state
 322
 323         /**
 324          * A string describing the current software version, and possibly
 325          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 326          * Use getServerVersion() to get machine-friendly information.
 327          *
 328          * @return string: Version information from the database server
 329          */
 330         public function getServerInfo() {
 331                 return $this->getServerVersion();
 332         }
 333
 334         /**
 335          * @return string: command delimiter used by this database engine
 336          */
 337         public function getDelimiter() {
 338                 return $this->delimiter;
 339         }
 340
 341         /**
 342          * Boolean, controls output of large amounts of debug information.
 343          * @param $debug bool|null
 344          *   - true to enable debugging
 345          *   - false to disable debugging
 346          *   - omitted or null to do nothing
 347          *
 348          * @return bool|null previous value of the flag
 349          */
 350         public function debug( $debug = null ) {
 351                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 352         }
 353
 354         /**
 355          * Turns buffering of SQL result sets on (true) or off (false). Default is
 356          * "on".
 357          *
 358          * Unbuffered queries are very troublesome in MySQL:
 359          *
 360          *   - If another query is executed while the first query is being read
 361          *     out, the first query is killed. This means you can't call normal
 362          *     MediaWiki functions while you are reading an unbuffered query result
 363          *     from a normal wfGetDB() connection.
 364          *
 365          *   - Unbuffered queries cause the MySQL server to use large amounts of
 366          *     memory and to hold broad locks which block other queries.
 367          *
 368          * If you want to limit client-side memory, it's almost always better to
 369          * split up queries into batches using a LIMIT clause than to switch off
 370          * buffering.
 371          *
 372          * @param $buffer null|bool
 373          *
 374          * @return null|bool The previous value of the flag
 375          */
 376         public function bufferResults( $buffer = null ) {
 377                 if ( is_null( $buffer ) ) {
 378                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 379                 } else {
 380                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 381                 }
 382         }
 383
 384         /**
 385          * Turns on (false) or off (true) the automatic generation and sending
 386          * of a "we're sorry, but there has been a database error" page on
 387          * database errors. Default is on (false). When turned off, the
 388          * code should use lastErrno() and lastError() to handle the
 389          * situation as appropriate.
 390          *
 391          * Do not use this function outside of the Database classes.
 392          *
 393          * @param $ignoreErrors bool|null
 394          *
 395          * @return bool The previous value of the flag.
 396          */
 397         public function ignoreErrors( $ignoreErrors = null ) {
 398                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 399         }
 400
 401         /**
 402          * Gets the current transaction level.
 403          *
 404          * Historically, transactions were allowed to be "nested". This is no
 405          * longer supported, so this function really only returns a boolean.
 406          *
 407          * @return int The previous value
 408          */
 409         public function trxLevel() {
 410                 return $this->mTrxLevel;
 411         }
 412
 413         /**
 414          * Get/set the number of errors logged. Only useful when errors are ignored
 415          * @param int $count The count to set, or omitted to leave it unchanged.
 416          * @return int The error count
 417          */
 418         public function errorCount( $count = null ) {
 419                 return wfSetVar( $this->mErrorCount, $count );
 420         }
 421
 422         /**
 423          * Get/set the table prefix.
 424          * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 425          * @return string The previous table prefix.
 426          */
 427         public function tablePrefix( $prefix = null ) {
 428                 return wfSetVar( $this->mTablePrefix, $prefix );
 429         }
 430
 431         /**
 432          * Set the filehandle to copy write statements to.
 433          *
 434          * @param $fh filehandle
 435          */
 436         public function setFileHandle( $fh ) {
 437                 $this->fileHandle = $fh;
 438         }
 439
 440         /**
 441          * Get properties passed down from the server info array of the load
 442          * balancer.
 443          *
 444          * @param string $name The entry of the info array to get, or null to get the
 445          *   whole array
 446          *
 447          * @return LoadBalancer|null
 448          */
 449         public function getLBInfo( $name = null ) {
 450                 if ( is_null( $name ) ) {
 451                         return $this->mLBInfo;
 452                 } else {
 453                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 454                                 return $this->mLBInfo[$name];
 455                         } else {
 456                                 return null;
 457                         }
 458                 }
 459         }
 460
 461         /**
 462          * Set the LB info array, or a member of it. If called with one parameter,
 463          * the LB info array is set to that parameter. If it is called with two
 464          * parameters, the member with the given name is set to the given value.
 465          *
 466          * @param $name
 467          * @param $value
 468          */
 469         public function setLBInfo( $name, $value = null ) {
 470                 if ( is_null( $value ) ) {
 471                         $this->mLBInfo = $name;
 472                 } else {
 473                         $this->mLBInfo[$name] = $value;
 474                 }
 475         }
 476
 477         /**
 478          * Set lag time in seconds for a fake slave
 479          *
 480          * @param $lag int
 481          */
 482         public function setFakeSlaveLag( $lag ) {
 483                 $this->mFakeSlaveLag = $lag;
 484         }
 485
 486         /**
 487          * Make this connection a fake master
 488          *
 489          * @param $enabled bool
 490          */
 491         public function setFakeMaster( $enabled = true ) {
 492                 $this->mFakeMaster = $enabled;
 493         }
 494
 495         /**
 496          * Returns true if this database supports (and uses) cascading deletes
 497          *
 498          * @return bool
 499          */
 500         public function cascadingDeletes() {
 501                 return false;
 502         }
 503
 504         /**
 505          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 506          *
 507          * @return bool
 508          */
 509         public function cleanupTriggers() {
 510                 return false;
 511         }
 512
 513         /**
 514          * Returns true if this database is strict about what can be put into an IP field.
 515          * Specifically, it uses a NULL value instead of an empty string.
 516          *
 517          * @return bool
 518          */
 519         public function strictIPs() {
 520                 return false;
 521         }
 522
 523         /**
 524          * Returns true if this database uses timestamps rather than integers
 525          *
 526          * @return bool
 527          */
 528         public function realTimestamps() {
 529                 return false;
 530         }
 531
 532         /**
 533          * Returns true if this database does an implicit sort when doing GROUP BY
 534          *
 535          * @return bool
 536          */
 537         public function implicitGroupby() {
 538                 return true;
 539         }
 540
 541         /**
 542          * Returns true if this database does an implicit order by when the column has an index
 543          * For example: SELECT page_title FROM page LIMIT 1
 544          *
 545          * @return bool
 546          */
 547         public function implicitOrderby() {
 548                 return true;
 549         }
 550
 551         /**
 552          * Returns true if this database can do a native search on IP columns
 553          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 554          *
 555          * @return bool
 556          */
 557         public function searchableIPs() {
 558                 return false;
 559         }
 560
 561         /**
 562          * Returns true if this database can use functional indexes
 563          *
 564          * @return bool
 565          */
 566         public function functionalIndexes() {
 567                 return false;
 568         }
 569
 570         /**
 571          * Return the last query that went through DatabaseBase::query()
 572          * @return String
 573          */
 574         public function lastQuery() {
 575                 return $this->mLastQuery;
 576         }
 577
 578         /**
 579          * Returns true if the connection may have been used for write queries.
 580          * Should return true if unsure.
 581          *
 582          * @return bool
 583          */
 584         public function doneWrites() {
 585                 return $this->mDoneWrites;
 586         }
 587
 588         /**
 589          * Returns true if there is a transaction open with possible write
 590          * queries or transaction pre-commit/idle callbacks waiting on it to finish.
 591          *
 592          * @return bool
 593          */
 594         public function writesOrCallbacksPending() {
 595                 return $this->mTrxLevel && (
 596                         $this->mTrxDoneWrites || $this->mTrxIdleCallbacks || $this->mTrxPreCommitCallbacks
 597                 );
 598         }
 599
 600         /**
 601          * Is a connection to the database open?
 602          * @return Boolean
 603          */
 604         public function isOpen() {
 605                 return $this->mOpened;
 606         }
 607
 608         /**
 609          * Set a flag for this connection
 610          *
 611          * @param $flag Integer: DBO_* constants from Defines.php:
 612          *   - DBO_DEBUG: output some debug info (same as debug())
 613          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 614          *   - DBO_TRX: automatically start transactions
 615          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 616          *       and removes it in command line mode
 617          *   - DBO_PERSISTENT: use persistant database connection
 618          */
 619         public function setFlag( $flag ) {
 620                 global $wgDebugDBTransactions;
 621                 $this->mFlags |= $flag;
 622                 if ( ( $flag & DBO_TRX ) & $wgDebugDBTransactions ) {
 623                         wfDebug( "Implicit transactions are now  disabled.\n" );
 624                 }
 625         }
 626
 627         /**
 628          * Clear a flag for this connection
 629          *
 630          * @param $flag : same as setFlag()'s $flag param
 631          */
 632         public function clearFlag( $flag ) {
 633                 global $wgDebugDBTransactions;
 634                 $this->mFlags &= ~$flag;
 635                 if ( ( $flag & DBO_TRX ) && $wgDebugDBTransactions ) {
 636                         wfDebug( "Implicit transactions are now disabled.\n" );
 637                 }
 638         }
 639
 640         /**
 641          * Returns a boolean whether the flag $flag is set for this connection
 642          *
 643          * @param $flag : same as setFlag()'s $flag param
 644          * @return Boolean
 645          */
 646         public function getFlag( $flag ) {
 647                 return !!( $this->mFlags & $flag );
 648         }
 649
 650         /**
 651          * General read-only accessor
 652          *
 653          * @param $name string
 654          *
 655          * @return string
 656          */
 657         public function getProperty( $name ) {
 658                 return $this->$name;
 659         }
 660
 661         /**
 662          * @return string
 663          */
 664         public function getWikiID() {
 665                 if ( $this->mTablePrefix ) {
 666                         return "{$this->mDBname}-{$this->mTablePrefix}";
 667                 } else {
 668                         return $this->mDBname;
 669                 }
 670         }
 671
 672         /**
 673          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 674          *
 675          * @return string
 676          */
 677         public function getSchemaPath() {
 678                 global $IP;
 679                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 680                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 681                 } else {
 682                         return "$IP/maintenance/tables.sql";
 683                 }
 684         }
 685
 686 # ------------------------------------------------------------------------------
 687 # Other functions
 688 # ------------------------------------------------------------------------------
 689
 690         /**
 691          * Constructor.
 692          *
 693          * FIXME: It is possible to construct a Database object with no associated
 694          * connection object, by specifying no parameters to __construct(). This
 695          * feature is deprecated and should be removed.
 696          *
 697          * DatabaseBase subclasses should not be constructed directly in external
 698          * code. DatabaseBase::factory() should be used instead.
 699          *
 700          * @param array Parameters passed from DatabaseBase::factory()
 701          */
 702         function __construct( $params = null ) {
 703                 global $wgDBprefix, $wgCommandLineMode, $wgDebugDBTransactions;
 704
 705                 $this->mTrxAtomicLevels = new SplStack;
 706
 707                 if ( is_array( $params ) ) { // MW 1.22
 708                         $server = $params['host'];
 709                         $user = $params['user'];
 710                         $password = $params['password'];
 711                         $dbName = $params['dbname'];
 712                         $flags = $params['flags'];
 713                         $tablePrefix = $params['tablePrefix'];
 714                         $foreign = $params['foreign'];
 715                 } else { // legacy calling pattern
 716                         wfDeprecated( __METHOD__ . " method called without parameter array.", "1.23" );
 717                         $args = func_get_args();
 718                         $server = isset( $args[0] ) ? $args[0] : false;
 719                         $user = isset( $args[1] ) ? $args[1] : false;
 720                         $password = isset( $args[2] ) ? $args[2] : false;
 721                         $dbName = isset( $args[3] ) ? $args[3] : false;
 722                         $flags = isset( $args[4] ) ? $args[4] : 0;
 723                         $tablePrefix = isset( $args[5] ) ? $args[5] : 'get from global';
 724                         $foreign = isset( $args[6] ) ? $args[6] : false;
 725                 }
 726
 727                 $this->mFlags = $flags;
 728                 if ( $this->mFlags & DBO_DEFAULT ) {
 729                         if ( $wgCommandLineMode ) {
 730                                 $this->mFlags &= ~DBO_TRX;
 731                                 if ( $wgDebugDBTransactions ) {
 732                                         wfDebug( "Implicit transaction open disabled.\n" );
 733                                 }
 734                         } else {
 735                                 $this->mFlags |= DBO_TRX;
 736                                 if ( $wgDebugDBTransactions ) {
 737                                         wfDebug( "Implicit transaction open enabled.\n" );
 738                                 }
 739                         }
 740                 }
 741
 742                 /** Get the default table prefix*/
 743                 if ( $tablePrefix == 'get from global' ) {
 744                         $this->mTablePrefix = $wgDBprefix;
 745                 } else {
 746                         $this->mTablePrefix = $tablePrefix;
 747                 }
 748
 749                 $this->mForeign = $foreign;
 750
 751                 if ( $user ) {
 752                         $this->open( $server, $user, $password, $dbName );
 753                 }
 754         }
 755
 756         /**
 757          * Called by serialize. Throw an exception when DB connection is serialized.
 758          * This causes problems on some database engines because the connection is
 759          * not restored on unserialize.
 760          */
 761         public function __sleep() {
 762                 throw new MWException( 'Database serialization may cause problems, since ' .
 763                         'the connection is not restored on wakeup.' );
 764         }
 765
 766         /**
 767          * Given a DB type, construct the name of the appropriate child class of
 768          * DatabaseBase. This is designed to replace all of the manual stuff like:
 769          *    $class = 'Database' . ucfirst( strtolower( $dbType ) );
 770          * as well as validate against the canonical list of DB types we have
 771          *
 772          * This factory function is mostly useful for when you need to connect to a
 773          * database other than the MediaWiki default (such as for external auth,
 774          * an extension, et cetera). Do not use this to connect to the MediaWiki
 775          * database. Example uses in core:
 776          * @see LoadBalancer::reallyOpenConnection()
 777          * @see ForeignDBRepo::getMasterDB()
 778          * @see WebInstaller_DBConnect::execute()
 779          *
 780          * @since 1.18
 781          *
 782          * @param string $dbType A possible DB type
 783          * @param array $p An array of options to pass to the constructor.
 784          *    Valid options are: host, user, password, dbname, flags, tablePrefix, driver
 785          * @return DatabaseBase subclass or null
 786          */
 787         final public static function factory( $dbType, $p = array() ) {
 788                 $canonicalDBTypes = array(
 789                         'mysql' => array( 'mysqli', 'mysql' ),
 790                         'postgres' => array(),
 791                         'sqlite' => array(),
 792                         'oracle' => array(),
 793                         'mssql' => array(),
 794                 );
 795
 796                 $driver = false;
 797                 $dbType = strtolower( $dbType );
 798                 if ( isset( $canonicalDBTypes[$dbType] ) && $canonicalDBTypes[$dbType] ) {
 799                         $possibleDrivers = $canonicalDBTypes[$dbType];
 800                         if ( !empty( $p['driver'] ) ) {
 801                                 if ( in_array( $p['driver'], $possibleDrivers ) ) {
 802                                         $driver = $p['driver'];
 803                                 } else {
 804                                         throw new MWException( __METHOD__ .
 805                                                 " cannot construct Database with type '$dbType' and driver '{$p['driver']}'" );
 806                                 }
 807                         } else {
 808                                 foreach ( $possibleDrivers as $posDriver ) {
 809                                         if ( extension_loaded( $posDriver ) ) {
 810                                                 $driver = $posDriver;
 811                                                 break;
 812                                         }
 813                                 }
 814                         }
 815                 } else {
 816                         $driver = $dbType;
 817                 }
 818                 if ( $driver === false ) {
 819                         throw new MWException( __METHOD__ .
 820                                 " no viable database extension found for type '$dbType'" );
 821                 }
 822
 823                 $class = 'Database' . ucfirst( $driver );
 824                 if ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) {
 825                         $params = array(
 826                                 'host' => isset( $p['host'] ) ? $p['host'] : false,
 827                                 'user' => isset( $p['user'] ) ? $p['user'] : false,
 828                                 'password' => isset( $p['password'] ) ? $p['password'] : false,
 829                                 'dbname' => isset( $p['dbname'] ) ? $p['dbname'] : false,
 830                                 'flags' => isset( $p['flags'] ) ? $p['flags'] : 0,
 831                                 'tablePrefix' => isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global',
 832                                 'foreign' => isset( $p['foreign'] ) ? $p['foreign'] : false
 833                         );
 834
 835                         return new $class( $params );
 836                 } else {
 837                         return null;
 838                 }
 839         }
 840
 841         protected function installErrorHandler() {
 842                 $this->mPHPError = false;
 843                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 844                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 845         }
 846
 847         /**
 848          * @return bool|string
 849          */
 850         protected function restoreErrorHandler() {
 851                 restore_error_handler();
 852                 if ( $this->htmlErrors !== false ) {
 853                         ini_set( 'html_errors', $this->htmlErrors );
 854                 }
 855                 if ( $this->mPHPError ) {
 856                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 857                         $error = preg_replace( '!^.*?:\s?(.*)$!', '$1', $error );
 858
 859                         return $error;
 860                 } else {
 861                         return false;
 862                 }
 863         }
 864
 865         /**
 866          * @param $errno
 867          * @param $errstr
 868          * @access private
 869          */
 870         public function connectionErrorHandler( $errno, $errstr ) {
 871                 $this->mPHPError = $errstr;
 872         }
 873
 874         /**
 875          * Closes a database connection.
 876          * if it is open : commits any open transactions
 877          *
 878          * @throws MWException
 879          * @return Bool operation success. true if already closed.
 880          */
 881         public function close() {
 882                 if ( count( $this->mTrxIdleCallbacks ) ) { // sanity
 883                         throw new MWException( "Transaction idle callbacks still pending." );
 884                 }
 885                 $this->mOpened = false;
 886                 if ( $this->mConn ) {
 887                         if ( $this->trxLevel() ) {
 888                                 if ( !$this->mTrxAutomatic ) {
 889                                         wfWarn( "Transaction still in progress (from {$this->mTrxFname}), " .
 890                                                 " performing implicit commit before closing connection!" );
 891                                 }
 892
 893                                 $this->commit( __METHOD__, 'flush' );
 894                         }
 895
 896                         $ret = $this->closeConnection();
 897                         $this->mConn = false;
 898
 899                         return $ret;
 900                 } else {
 901                         return true;
 902                 }
 903         }
 904
 905         /**
 906          * Closes underlying database connection
 907          * @since 1.20
 908          * @return bool: Whether connection was closed successfully
 909          */
 910         abstract protected function closeConnection();
 911
 912         /**
 913          * @param string $error fallback error message, used if none is given by DB
 914          * @throws DBConnectionError
 915          */
 916         function reportConnectionError( $error = 'Unknown error' ) {
 917                 $myError = $this->lastError();
 918                 if ( $myError ) {
 919                         $error = $myError;
 920                 }
 921
 922                 # New method
 923                 throw new DBConnectionError( $this, $error );
 924         }
 925
 926         /**
 927          * The DBMS-dependent part of query()
 928          *
 929          * @param  $sql String: SQL query.
 930          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 931          */
 932         abstract protected function doQuery( $sql );
 933
 934         /**
 935          * Determine whether a query writes to the DB.
 936          * Should return true if unsure.
 937          *
 938          * @param $sql string
 939          *
 940          * @return bool
 941          */
 942         public function isWriteQuery( $sql ) {
 943                 return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 944         }
 945
 946         /**
 947          * Run an SQL query and return the result. Normally throws a DBQueryError
 948          * on failure. If errors are ignored, returns false instead.
 949          *
 950          * In new code, the query wrappers select(), insert(), update(), delete(),
 951          * etc. should be used where possible, since they give much better DBMS
 952          * independence and automatically quote or validate user input in a variety
 953          * of contexts. This function is generally only useful for queries which are
 954          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 955          * as CREATE TABLE.
 956          *
 957          * However, the query wrappers themselves should call this function.
 958          *
 959          * @param  $sql        String: SQL query
 960          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 961          *     comment (you can use __METHOD__ or add some extra info)
 962          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 963          *     maybe best to catch the exception instead?
 964          * @throws MWException
 965          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 966          *     for a successful read query, or false on failure if $tempIgnore set
 967          */
 968         public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
 969                 global $wgUser, $wgDebugDBTransactions;
 970
 971                 $this->mLastQuery = $sql;
 972                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 973                         # Set a flag indicating that writes have been done
 974                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 975                         $this->mDoneWrites = true;
 976                 }
 977
 978                 # Add a comment for easy SHOW PROCESSLIST interpretation
 979                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 980                         $userName = $wgUser->getName();
 981                         if ( mb_strlen( $userName ) > 15 ) {
 982                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 983                         }
 984                         $userName = str_replace( '/', '', $userName );
 985                 } else {
 986                         $userName = '';
 987                 }
 988
 989                 // Add trace comment to the begin of the sql string, right after the operator.
 990                 // Or, for one-word queries (like "BEGIN" or COMMIT") add it to the end (bug 42598)
 991                 $commentedSql = preg_replace( '/\s|$/', " /* $fname $userName */ ", $sql, 1 );
 992
 993                 # If DBO_TRX is set, start a transaction
 994                 if ( ( $this->mFlags & DBO_TRX ) && !$this->mTrxLevel &&
 995                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK'
 996                 ) {
 997                         # Avoid establishing transactions for SHOW and SET statements too -
 998                         # that would delay transaction initializations to once connection
 999                         # is really used by application
1000                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
1001                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 ) {
1002                                 if ( $wgDebugDBTransactions ) {
1003                                         wfDebug( "Implicit transaction start.\n" );
1004                                 }
1005                                 $this->begin( __METHOD__ . " ($fname)" );
1006                                 $this->mTrxAutomatic = true;
1007                         }
1008                 }
1009
1010                 # Keep track of whether the transaction has write queries pending
1011                 if ( $this->mTrxLevel && !$this->mTrxDoneWrites && $this->isWriteQuery( $sql ) ) {
1012                         $this->mTrxDoneWrites = true;
1013                         Profiler::instance()->transactionWritingIn( $this->mServer, $this->mDBname );
1014                 }
1015
1016                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
1017                 if ( !Profiler::instance()->isStub() ) {
1018                         # generalizeSQL will probably cut down the query to reasonable
1019                         # logging size most of the time. The substr is really just a sanity check.
1020                         if ( $isMaster ) {
1021                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1022                                 $totalProf = 'DatabaseBase::query-master';
1023                         } else {
1024                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
1025                                 $totalProf = 'DatabaseBase::query';
1026                         }
1027                         wfProfileIn( $totalProf );
1028                         wfProfileIn( $queryProf );
1029                 }
1030
1031                 if ( $this->debug() ) {
1032                         static $cnt = 0;
1033
1034                         $cnt++;
1035                         $sqlx = substr( $commentedSql, 0, 500 );
1036                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
1037
1038                         $master = $isMaster ? 'master' : 'slave';
1039                         wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
1040                 }
1041
1042                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
1043
1044                 # Do the query and handle errors
1045                 $ret = $this->doQuery( $commentedSql );
1046
1047                 MWDebug::queryTime( $queryId );
1048
1049                 # Try reconnecting if the connection was lost
1050                 if ( false === $ret && $this->wasErrorReissuable() ) {
1051                         # Transaction is gone, like it or not
1052                         $hadTrx = $this->mTrxLevel; // possible lost transaction
1053                         wfDebug( "Connection lost, reconnecting...\n" );
1054                         $this->mTrxLevel = 0;
1055                         wfDebug( "Connection lost, reconnecting...\n" );
1056
1057                         if ( $this->ping() ) {
1058                                 wfDebug( "Reconnected\n" );
1059                                 $sqlx = substr( $commentedSql, 0, 500 );
1060                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
1061                                 global $wgRequestTime;
1062                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
1063                                 if ( $elapsed < 300 ) {
1064                                         # Not a database error to lose a transaction after a minute or two
1065                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
1066                                 }
1067                                 if ( !$hadTrx ) {
1068                                         # Should be safe to silently retry
1069                                         $ret = $this->doQuery( $commentedSql );
1070                                 }
1071                         } else {
1072                                 wfDebug( "Failed\n" );
1073                         }
1074                 }
1075
1076                 if ( false === $ret ) {
1077                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
1078                 }
1079
1080                 if ( !Profiler::instance()->isStub() ) {
1081                         wfProfileOut( $queryProf );
1082                         wfProfileOut( $totalProf );
1083                 }
1084
1085                 return $this->resultObject( $ret );
1086         }
1087
1088         /**
1089          * Report a query error. Log the error, and if neither the object ignore
1090          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
1091          *
1092          * @param $error String
1093          * @param $errno Integer
1094          * @param $sql String
1095          * @param $fname String
1096          * @param $tempIgnore Boolean
1097          * @throws DBQueryError
1098          */
1099         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
1100                 # Ignore errors during error handling to avoid infinite recursion
1101                 $ignore = $this->ignoreErrors( true );
1102                 ++$this->mErrorCount;
1103
1104                 if ( $ignore || $tempIgnore ) {
1105                         wfDebug( "SQL ERROR (ignored): $error\n" );
1106                         $this->ignoreErrors( $ignore );
1107                 } else {
1108                         $sql1line = str_replace( "\n", "\\n", $sql );
1109                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
1110                         wfDebug( "SQL ERROR: " . $error . "\n" );
1111                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
1112                 }
1113         }
1114
1115         /**
1116          * Intended to be compatible with the PEAR::DB wrapper functions.
1117          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1118          *
1119          * ? = scalar value, quoted as necessary
1120          * ! = raw SQL bit (a function for instance)
1121          * & = filename; reads the file and inserts as a blob
1122          *     (we don't use this though...)
1123          *
1124          * @param $sql string
1125          * @param $func string
1126          *
1127          * @return array
1128          */
1129         protected function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
1130                 /* MySQL doesn't support prepared statements (yet), so just
1131                    pack up the query for reference. We'll manually replace
1132                    the bits later. */
1133                 return array( 'query' => $sql, 'func' => $func );
1134         }
1135
1136         /**
1137          * Free a prepared query, generated by prepare().
1138          * @param $prepared
1139          */
1140         protected function freePrepared( $prepared ) {
1141                 /* No-op by default */
1142         }
1143
1144         /**
1145          * Execute a prepared query with the various arguments
1146          * @param string $prepared the prepared sql
1147          * @param $args Mixed: Either an array here, or put scalars as varargs
1148          *
1149          * @return ResultWrapper
1150          */
1151         public function execute( $prepared, $args = null ) {
1152                 if ( !is_array( $args ) ) {
1153                         # Pull the var args
1154                         $args = func_get_args();
1155                         array_shift( $args );
1156                 }
1157
1158                 $sql = $this->fillPrepared( $prepared['query'], $args );
1159
1160                 return $this->query( $sql, $prepared['func'] );
1161         }
1162
1163         /**
1164          * For faking prepared SQL statements on DBs that don't support it directly.
1165          *
1166          * @param string $preparedQuery a 'preparable' SQL statement
1167          * @param array $args of arguments to fill it with
1168          * @return string executable SQL
1169          */
1170         public function fillPrepared( $preparedQuery, $args ) {
1171                 reset( $args );
1172                 $this->preparedArgs =& $args;
1173
1174                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1175                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1176         }
1177
1178         /**
1179          * preg_callback func for fillPrepared()
1180          * The arguments should be in $this->preparedArgs and must not be touched
1181          * while we're doing this.
1182          *
1183          * @param $matches Array
1184          * @throws DBUnexpectedError
1185          * @return String
1186          */
1187         protected function fillPreparedArg( $matches ) {
1188                 switch ( $matches[1] ) {
1189                         case '\\?':
1190                                 return '?';
1191                         case '\\!':
1192                                 return '!';
1193                         case '\\&':
1194                                 return '&';
1195                 }
1196
1197                 list( /* $n */, $arg ) = each( $this->preparedArgs );
1198
1199                 switch ( $matches[1] ) {
1200                         case '?':
1201                                 return $this->addQuotes( $arg );
1202                         case '!':
1203                                 return $arg;
1204                         case '&':
1205                                 # return $this->addQuotes( file_get_contents( $arg ) );
1206                                 throw new DBUnexpectedError(
1207                                         $this,
1208                                         '& mode is not implemented. If it\'s really needed, uncomment the line above.'
1209                                 );
1210                         default:
1211                                 throw new DBUnexpectedError(
1212                                         $this,
1213                                         'Received invalid match. This should never happen!'
1214                                 );
1215                 }
1216         }
1217
1218         /**
1219          * Free a result object returned by query() or select(). It's usually not
1220          * necessary to call this, just use unset() or let the variable holding
1221          * the result object go out of scope.
1222          *
1223          * @param $res Mixed: A SQL result
1224          */
1225         public function freeResult( $res ) {
1226         }
1227
1228         /**
1229          * A SELECT wrapper which returns a single field from a single result row.
1230          *
1231          * Usually throws a DBQueryError on failure. If errors are explicitly
1232          * ignored, returns false on failure.
1233          *
1234          * If no result rows are returned from the query, false is returned.
1235          *
1236          * @param string|array $table Table name. See DatabaseBase::select() for details.
1237          * @param string $var The field name to select. This must be a valid SQL
1238          *   fragment: do not use unvalidated user input.
1239          * @param string|array $cond The condition array. See DatabaseBase::select() for details.
1240          * @param string $fname The function name of the caller.
1241          * @param string|array $options The query options. See DatabaseBase::select() for details.
1242          *
1243          * @return bool|mixed The value from the field, or false on failure.
1244          */
1245         public function selectField( $table, $var, $cond = '', $fname = __METHOD__,
1246                 $options = array()
1247         ) {
1248                 if ( !is_array( $options ) ) {
1249                         $options = array( $options );
1250                 }
1251
1252                 $options['LIMIT'] = 1;
1253
1254                 $res = $this->select( $table, $var, $cond, $fname, $options );
1255
1256                 if ( $res === false || !$this->numRows( $res ) ) {
1257                         return false;
1258                 }
1259
1260                 $row = $this->fetchRow( $res );
1261
1262                 if ( $row !== false ) {
1263                         return reset( $row );
1264                 } else {
1265                         return false;
1266                 }
1267         }
1268
1269         /**
1270          * Returns an optional USE INDEX clause to go after the table, and a
1271          * string to go at the end of the query.
1272          *
1273          * @param array $options associative array of options to be turned into
1274          *              an SQL query, valid keys are listed in the function.
1275          * @return Array
1276          * @see DatabaseBase::select()
1277          */
1278         public function makeSelectOptions( $options ) {
1279                 $preLimitTail = $postLimitTail = '';
1280                 $startOpts = '';
1281
1282                 $noKeyOptions = array();
1283
1284                 foreach ( $options as $key => $option ) {
1285                         if ( is_numeric( $key ) ) {
1286                                 $noKeyOptions[$option] = true;
1287                         }
1288                 }
1289
1290                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1291
1292                 $preLimitTail .= $this->makeOrderBy( $options );
1293
1294                 // if (isset($options['LIMIT'])) {
1295                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1296                 //              isset($options['OFFSET']) ? $options['OFFSET']
1297                 //              : false);
1298                 // }
1299
1300                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1301                         $postLimitTail .= ' FOR UPDATE';
1302                 }
1303
1304                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1305                         $postLimitTail .= ' LOCK IN SHARE MODE';
1306                 }
1307
1308                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1309                         $startOpts .= 'DISTINCT';
1310                 }
1311
1312                 # Various MySQL extensions
1313                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1314                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1315                 }
1316
1317                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1318                         $startOpts .= ' HIGH_PRIORITY';
1319                 }
1320
1321                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1322                         $startOpts .= ' SQL_BIG_RESULT';
1323                 }
1324
1325                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1326                         $startOpts .= ' SQL_BUFFER_RESULT';
1327                 }
1328
1329                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1330                         $startOpts .= ' SQL_SMALL_RESULT';
1331                 }
1332
1333                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1334                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1335                 }
1336
1337                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1338                         $startOpts .= ' SQL_CACHE';
1339                 }
1340
1341                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1342                         $startOpts .= ' SQL_NO_CACHE';
1343                 }
1344
1345                 if ( isset( $options['USE INDEX'] ) && is_string( $options['USE INDEX'] ) ) {
1346                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1347                 } else {
1348                         $useIndex = '';
1349                 }
1350
1351                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1352         }
1353
1354         /**
1355          * Returns an optional GROUP BY with an optional HAVING
1356          *
1357          * @param array $options associative array of options
1358          * @return string
1359          * @see DatabaseBase::select()
1360          * @since 1.21
1361          */
1362         public function makeGroupByWithHaving( $options ) {
1363                 $sql = '';
1364                 if ( isset( $options['GROUP BY'] ) ) {
1365                         $gb = is_array( $options['GROUP BY'] )
1366                                 ? implode( ',', $options['GROUP BY'] )
1367                                 : $options['GROUP BY'];
1368                         $sql .= ' GROUP BY ' . $gb;
1369                 }
1370                 if ( isset( $options['HAVING'] ) ) {
1371                         $having = is_array( $options['HAVING'] )
1372                                 ? $this->makeList( $options['HAVING'], LIST_AND )
1373                                 : $options['HAVING'];
1374                         $sql .= ' HAVING ' . $having;
1375                 }
1376
1377                 return $sql;
1378         }
1379
1380         /**
1381          * Returns an optional ORDER BY
1382          *
1383          * @param array $options associative array of options
1384          * @return string
1385          * @see DatabaseBase::select()
1386          * @since 1.21
1387          */
1388         public function makeOrderBy( $options ) {
1389                 if ( isset( $options['ORDER BY'] ) ) {
1390                         $ob = is_array( $options['ORDER BY'] )
1391                                 ? implode( ',', $options['ORDER BY'] )
1392                                 : $options['ORDER BY'];
1393
1394                         return ' ORDER BY ' . $ob;
1395                 }
1396
1397                 return '';
1398         }
1399
1400         /**
1401          * Execute a SELECT query constructed using the various parameters provided.
1402          * See below for full details of the parameters.
1403          *
1404          * @param string|array $table Table name
1405          * @param string|array $vars Field names
1406          * @param string|array $conds Conditions
1407          * @param string $fname Caller function name
1408          * @param array $options Query options
1409          * @param $join_conds Array Join conditions
1410          *
1411          * @param $table string|array
1412          *
1413          * May be either an array of table names, or a single string holding a table
1414          * name. If an array is given, table aliases can be specified, for example:
1415          *
1416          *    array( 'a' => 'user' )
1417          *
1418          * This includes the user table in the query, with the alias "a" available
1419          * for use in field names (e.g. a.user_name).
1420          *
1421          * All of the table names given here are automatically run through
1422          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1423          * added, and various other table name mappings to be performed.
1424          *
1425          *
1426          * @param $vars string|array
1427          *
1428          * May be either a field name or an array of field names. The field names
1429          * can be complete fragments of SQL, for direct inclusion into the SELECT
1430          * query. If an array is given, field aliases can be specified, for example:
1431          *
1432          *   array( 'maxrev' => 'MAX(rev_id)' )
1433          *
1434          * This includes an expression with the alias "maxrev" in the query.
1435          *
1436          * If an expression is given, care must be taken to ensure that it is
1437          * DBMS-independent.
1438          *
1439          *
1440          * @param $conds string|array
1441          *
1442          * May be either a string containing a single condition, or an array of
1443          * conditions. If an array is given, the conditions constructed from each
1444          * element are combined with AND.
1445          *
1446          * Array elements may take one of two forms:
1447          *
1448          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1449          *   - Elements with a string key are interpreted as equality conditions,
1450          *     where the key is the field name.
1451          *     - If the value of such an array element is a scalar (such as a
1452          *       string), it will be treated as data and thus quoted appropriately.
1453          *       If it is null, an IS NULL clause will be added.
1454          *     - If the value is an array, an IN(...) clause will be constructed,
1455          *       such that the field name may match any of the elements in the
1456          *       array. The elements of the array will be quoted.
1457          *
1458          * Note that expressions are often DBMS-dependent in their syntax.
1459          * DBMS-independent wrappers are provided for constructing several types of
1460          * expression commonly used in condition queries. See:
1461          *    - DatabaseBase::buildLike()
1462          *    - DatabaseBase::conditional()
1463          *
1464          *
1465          * @param $options string|array
1466          *
1467          * Optional: Array of query options. Boolean options are specified by
1468          * including them in the array as a string value with a numeric key, for
1469          * example:
1470          *
1471          *    array( 'FOR UPDATE' )
1472          *
1473          * The supported options are:
1474          *
1475          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1476          *     with LIMIT can theoretically be used for paging through a result set,
1477          *     but this is discouraged in MediaWiki for performance reasons.
1478          *
1479          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1480          *     and then the first rows are taken until the limit is reached. LIMIT
1481          *     is applied to a result set after OFFSET.
1482          *
1483          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1484          *     changed until the next COMMIT.
1485          *
1486          *   - DISTINCT: Boolean: return only unique result rows.
1487          *
1488          *   - GROUP BY: May be either an SQL fragment string naming a field or
1489          *     expression to group by, or an array of such SQL fragments.
1490          *
1491          *   - HAVING: May be either an string containing a HAVING clause or an array of
1492          *     conditions building the HAVING clause. If an array is given, the conditions
1493          *     constructed from each element are combined with AND.
1494          *
1495          *   - ORDER BY: May be either an SQL fragment giving a field name or
1496          *     expression to order by, or an array of such SQL fragments.
1497          *
1498          *   - USE INDEX: This may be either a string giving the index name to use
1499          *     for the query, or an array. If it is an associative array, each key
1500          *     gives the table name (or alias), each value gives the index name to
1501          *     use for that table. All strings are SQL fragments and so should be
1502          *     validated by the caller.
1503          *
1504          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1505          *     instead of SELECT.
1506          *
1507          * And also the following boolean MySQL extensions, see the MySQL manual
1508          * for documentation:
1509          *
1510          *    - LOCK IN SHARE MODE
1511          *    - STRAIGHT_JOIN
1512          *    - HIGH_PRIORITY
1513          *    - SQL_BIG_RESULT
1514          *    - SQL_BUFFER_RESULT
1515          *    - SQL_SMALL_RESULT
1516          *    - SQL_CALC_FOUND_ROWS
1517          *    - SQL_CACHE
1518          *    - SQL_NO_CACHE
1519          *
1520          *
1521          * @param $join_conds string|array
1522          *
1523          * Optional associative array of table-specific join conditions. In the
1524          * most common case, this is unnecessary, since the join condition can be
1525          * in $conds. However, it is useful for doing a LEFT JOIN.
1526          *
1527          * The key of the array contains the table name or alias. The value is an
1528          * array with two elements, numbered 0 and 1. The first gives the type of
1529          * join, the second is an SQL fragment giving the join condition for that
1530          * table. For example:
1531          *
1532          *    array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )
1533          *
1534          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1535          *   with no rows in it will be returned. If there was a query error, a
1536          *   DBQueryError exception will be thrown, except if the "ignore errors"
1537          *   option was set, in which case false will be returned.
1538          */
1539         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
1540                 $options = array(), $join_conds = array() ) {
1541                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1542
1543                 return $this->query( $sql, $fname );
1544         }
1545
1546         /**
1547          * The equivalent of DatabaseBase::select() except that the constructed SQL
1548          * is returned, instead of being immediately executed. This can be useful for
1549          * doing UNION queries, where the SQL text of each query is needed. In general,
1550          * however, callers outside of Database classes should just use select().
1551          *
1552          * @param string|array $table Table name
1553          * @param string|array $vars Field names
1554          * @param string|array $conds Conditions
1555          * @param string $fname Caller function name
1556          * @param string|array $options Query options
1557          * @param $join_conds string|array Join conditions
1558          *
1559          * @return string SQL query string.
1560          * @see DatabaseBase::select()
1561          */
1562         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
1563                 $options = array(), $join_conds = array()
1564         ) {
1565                 if ( is_array( $vars ) ) {
1566                         $vars = implode( ',', $this->fieldNamesWithAlias( $vars ) );
1567                 }
1568
1569                 $options = (array)$options;
1570                 $useIndexes = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1571                         ? $options['USE INDEX']
1572                         : array();
1573
1574                 if ( is_array( $table ) ) {
1575                         $from = ' FROM ' .
1576                                 $this->tableNamesWithUseIndexOrJOIN( $table, $useIndexes, $join_conds );
1577                 } elseif ( $table != '' ) {
1578                         if ( $table[0] == ' ' ) {
1579                                 $from = ' FROM ' . $table;
1580                         } else {
1581                                 $from = ' FROM ' .
1582                                         $this->tableNamesWithUseIndexOrJOIN( array( $table ), $useIndexes, array() );
1583                         }
1584                 } else {
1585                         $from = '';
1586                 }
1587
1588                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) =
1589                         $this->makeSelectOptions( $options );
1590
1591                 if ( !empty( $conds ) ) {
1592                         if ( is_array( $conds ) ) {
1593                                 $conds = $this->makeList( $conds, LIST_AND );
1594                         }
1595                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1596                 } else {
1597                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1598                 }
1599
1600                 if ( isset( $options['LIMIT'] ) ) {
1601                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1602                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1603                 }
1604                 $sql = "$sql $postLimitTail";
1605
1606                 if ( isset( $options['EXPLAIN'] ) ) {
1607                         $sql = 'EXPLAIN ' . $sql;
1608                 }
1609
1610                 return $sql;
1611         }
1612
1613         /**
1614          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1615          * that a single row object is returned. If the query returns no rows,
1616          * false is returned.
1617          *
1618          * @param string|array $table Table name
1619          * @param string|array $vars Field names
1620          * @param array $conds Conditions
1621          * @param string $fname Caller function name
1622          * @param string|array $options Query options
1623          * @param $join_conds array|string Join conditions
1624          *
1625          * @return object|bool
1626          */
1627         public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
1628                 $options = array(), $join_conds = array()
1629         ) {
1630                 $options = (array)$options;
1631                 $options['LIMIT'] = 1;
1632                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1633
1634                 if ( $res === false ) {
1635                         return false;
1636                 }
1637
1638                 if ( !$this->numRows( $res ) ) {
1639                         return false;
1640                 }
1641
1642                 $obj = $this->fetchObject( $res );
1643
1644                 return $obj;
1645         }
1646
1647         /**
1648          * Estimate rows in dataset.
1649          *
1650          * MySQL allows you to estimate the number of rows that would be returned
1651          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1652          * index cardinality statistics, and is notoriously inaccurate, especially
1653          * when large numbers of rows have recently been added or deleted.
1654          *
1655          * For DBMSs that don't support fast result size estimation, this function
1656          * will actually perform the SELECT COUNT(*).
1657          *
1658          * Takes the same arguments as DatabaseBase::select().
1659          *
1660          * @param string $table table name
1661          * @param array|string $vars : unused
1662          * @param array|string $conds : filters on the table
1663          * @param string $fname function name for profiling
1664          * @param array $options options for select
1665          * @return Integer: row count
1666          */
1667         public function estimateRowCount( $table, $vars = '*', $conds = '',
1668                 $fname = __METHOD__, $options = array()
1669         ) {
1670                 $rows = 0;
1671                 $res = $this->select( $table, array( 'rowcount' => 'COUNT(*)' ), $conds, $fname, $options );
1672
1673                 if ( $res ) {
1674                         $row = $this->fetchRow( $res );
1675                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1676                 }
1677
1678                 return $rows;
1679         }
1680
1681         /**
1682          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1683          * It's only slightly flawed. Don't use for anything important.
1684          *
1685          * @param string $sql A SQL Query
1686          *
1687          * @return string
1688          */
1689         static function generalizeSQL( $sql ) {
1690                 # This does the same as the regexp below would do, but in such a way
1691                 # as to avoid crashing php on some large strings.
1692                 # $sql = preg_replace( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql );
1693
1694                 $sql = str_replace( "\\\\", '', $sql );
1695                 $sql = str_replace( "\\'", '', $sql );
1696                 $sql = str_replace( "\\\"", '', $sql );
1697                 $sql = preg_replace( "/'.*'/s", "'X'", $sql );
1698                 $sql = preg_replace( '/".*"/s', "'X'", $sql );
1699
1700                 # All newlines, tabs, etc replaced by single space
1701                 $sql = preg_replace( '/\s+/', ' ', $sql );
1702
1703                 # All numbers => N
1704                 $sql = preg_replace( '/-?\d+(,-?\d+)+/s', 'N,...,N', $sql );
1705                 $sql = preg_replace( '/-?\d+/s', 'N', $sql );
1706
1707                 return $sql;
1708         }
1709
1710         /**
1711          * Determines whether a field exists in a table
1712          *
1713          * @param string $table table name
1714          * @param string $field filed to check on that table
1715          * @param string $fname calling function name (optional)
1716          * @return Boolean: whether $table has filed $field
1717          */
1718         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1719                 $info = $this->fieldInfo( $table, $field );
1720
1721                 return (bool)$info;
1722         }
1723
1724         /**
1725          * Determines whether an index exists
1726          * Usually throws a DBQueryError on failure
1727          * If errors are explicitly ignored, returns NULL on failure
1728          *
1729          * @param $table
1730          * @param $index
1731          * @param $fname string
1732          *
1733          * @return bool|null
1734          */
1735         public function indexExists( $table, $index, $fname = __METHOD__ ) {
1736                 if ( !$this->tableExists( $table ) ) {
1737                         return null;
1738                 }
1739
1740                 $info = $this->indexInfo( $table, $index, $fname );
1741                 if ( is_null( $info ) ) {
1742                         return null;
1743                 } else {
1744                         return $info !== false;
1745                 }
1746         }
1747
1748         /**
1749          * Query whether a given table exists
1750          *
1751          * @param $table string
1752          * @param $fname string
1753          *
1754          * @return bool
1755          */
1756         public function tableExists( $table, $fname = __METHOD__ ) {
1757                 $table = $this->tableName( $table );
1758                 $old = $this->ignoreErrors( true );
1759                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1760                 $this->ignoreErrors( $old );
1761
1762                 return (bool)$res;
1763         }
1764
1765         /**
1766          * mysql_field_type() wrapper
1767          * @param $res
1768          * @param $index
1769          * @return string
1770          */
1771         public function fieldType( $res, $index ) {
1772                 if ( $res instanceof ResultWrapper ) {
1773                         $res = $res->result;
1774                 }
1775
1776                 return mysql_field_type( $res, $index );
1777         }
1778
1779         /**
1780          * Determines if a given index is unique
1781          *
1782          * @param $table string
1783          * @param $index string
1784          *
1785          * @return bool
1786          */
1787         public function indexUnique( $table, $index ) {
1788                 $indexInfo = $this->indexInfo( $table, $index );
1789
1790                 if ( !$indexInfo ) {
1791                         return null;
1792                 }
1793
1794                 return !$indexInfo[0]->Non_unique;
1795         }
1796
1797         /**
1798          * Helper for DatabaseBase::insert().
1799          *
1800          * @param $options array
1801          * @return string
1802          */
1803         protected function makeInsertOptions( $options ) {
1804                 return implode( ' ', $options );
1805         }
1806
1807         /**
1808          * INSERT wrapper, inserts an array into a table.
1809          *
1810          * $a may be either:
1811          *
1812          *   - A single associative array. The array keys are the field names, and
1813          *     the values are the values to insert. The values are treated as data
1814          *     and will be quoted appropriately. If NULL is inserted, this will be
1815          *     converted to a database NULL.
1816          *   - An array with numeric keys, holding a list of associative arrays.
1817          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1818          *     each subarray must be identical to each other, and in the same order.
1819          *
1820          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1821          * returns success.
1822          *
1823          * $options is an array of options, with boolean options encoded as values
1824          * with numeric keys, in the same style as $options in
1825          * DatabaseBase::select(). Supported options are:
1826          *
1827          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1828          *     any rows which cause duplicate key errors are not inserted. It's
1829          *     possible to determine how many rows were successfully inserted using
1830          *     DatabaseBase::affectedRows().
1831          *
1832          * @param $table   String Table name. This will be passed through
1833          *                 DatabaseBase::tableName().
1834          * @param $a       Array of rows to insert
1835          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1836          * @param array $options of options
1837          *
1838          * @return bool
1839          */
1840         public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
1841                 # No rows to insert, easy just return now
1842                 if ( !count( $a ) ) {
1843                         return true;
1844                 }
1845
1846                 $table = $this->tableName( $table );
1847
1848                 if ( !is_array( $options ) ) {
1849                         $options = array( $options );
1850                 }
1851
1852                 $fh = null;
1853                 if ( isset( $options['fileHandle'] ) ) {
1854                         $fh = $options['fileHandle'];
1855                 }
1856                 $options = $this->makeInsertOptions( $options );
1857
1858                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1859                         $multi = true;
1860                         $keys = array_keys( $a[0] );
1861                 } else {
1862                         $multi = false;
1863                         $keys = array_keys( $a );
1864                 }
1865
1866                 $sql = 'INSERT ' . $options .
1867                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1868
1869                 if ( $multi ) {
1870                         $first = true;
1871                         foreach ( $a as $row ) {
1872                                 if ( $first ) {
1873                                         $first = false;
1874                                 } else {
1875                                         $sql .= ',';
1876                                 }
1877                                 $sql .= '(' . $this->makeList( $row ) . ')';
1878                         }
1879                 } else {
1880                         $sql .= '(' . $this->makeList( $a ) . ')';
1881                 }
1882
1883                 if ( $fh !== null && false === fwrite( $fh, $sql ) ) {
1884                         return false;
1885                 } elseif ( $fh !== null ) {
1886                         return true;
1887                 }
1888
1889                 return (bool)$this->query( $sql, $fname );
1890         }
1891
1892         /**
1893          * Make UPDATE options for the DatabaseBase::update function
1894          *
1895          * @param array $options The options passed to DatabaseBase::update
1896          * @return string
1897          */
1898         protected function makeUpdateOptions( $options ) {
1899                 if ( !is_array( $options ) ) {
1900                         $options = array( $options );
1901                 }
1902
1903                 $opts = array();
1904
1905                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1906                         $opts[] = $this->lowPriorityOption();
1907                 }
1908
1909                 if ( in_array( 'IGNORE', $options ) ) {
1910                         $opts[] = 'IGNORE';
1911                 }
1912
1913                 return implode( ' ', $opts );
1914         }
1915
1916         /**
1917          * UPDATE wrapper. Takes a condition array and a SET array.
1918          *
1919          * @param $table  String name of the table to UPDATE. This will be passed through
1920          *                DatabaseBase::tableName().
1921          *
1922          * @param array $values An array of values to SET. For each array element,
1923          *                the key gives the field name, and the value gives the data
1924          *                to set that field to. The data will be quoted by
1925          *                DatabaseBase::addQuotes().
1926          *
1927          * @param $conds  Array:  An array of conditions (WHERE). See
1928          *                DatabaseBase::select() for the details of the format of
1929          *                condition arrays. Use '*' to update all rows.
1930          *
1931          * @param $fname  String: The function name of the caller (from __METHOD__),
1932          *                for logging and profiling.
1933          *
1934          * @param array $options An array of UPDATE options, can be:
1935          *                   - IGNORE: Ignore unique key conflicts
1936          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1937          * @return Boolean
1938          */
1939         function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
1940                 $table = $this->tableName( $table );
1941                 $opts = $this->makeUpdateOptions( $options );
1942                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1943
1944                 if ( $conds !== array() && $conds !== '*' ) {
1945                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1946                 }
1947
1948                 return $this->query( $sql, $fname );
1949         }
1950
1951         /**
1952          * Makes an encoded list of strings from an array
1953          * @param array $a containing the data
1954          * @param int $mode Constant
1955          *      - LIST_COMMA:          comma separated, no field names
1956          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1957          *        the documentation for $conds in DatabaseBase::select().
1958          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1959          *      - LIST_SET:            comma separated with field names, like a SET clause
1960          *      - LIST_NAMES:          comma separated field names
1961          *
1962          * @throws MWException|DBUnexpectedError
1963          * @return string
1964          */
1965         public function makeList( $a, $mode = LIST_COMMA ) {
1966                 if ( !is_array( $a ) ) {
1967                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1968                 }
1969
1970                 $first = true;
1971                 $list = '';
1972
1973                 foreach ( $a as $field => $value ) {
1974                         if ( !$first ) {
1975                                 if ( $mode == LIST_AND ) {
1976                                         $list .= ' AND ';
1977                                 } elseif ( $mode == LIST_OR ) {
1978                                         $list .= ' OR ';
1979                                 } else {
1980                                         $list .= ',';
1981                                 }
1982                         } else {
1983                                 $first = false;
1984                         }
1985
1986                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1987                                 $list .= "($value)";
1988                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1989                                 $list .= "$value";
1990                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1991                                 if ( count( $value ) == 0 ) {
1992                                         throw new MWException( __METHOD__ . ": empty input for field $field" );
1993                                 } elseif ( count( $value ) == 1 ) {
1994                                         // Special-case single values, as IN isn't terribly efficient
1995                                         // Don't necessarily assume the single key is 0; we don't
1996                                         // enforce linear numeric ordering on other arrays here.
1997                                         $value = array_values( $value );
1998                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1999                                 } else {
2000                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
2001                                 }
2002                         } elseif ( $value === null ) {
2003                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
2004                                         $list .= "$field IS ";
2005                                 } elseif ( $mode == LIST_SET ) {
2006                                         $list .= "$field = ";
2007                                 }
2008                                 $list .= 'NULL';
2009                         } else {
2010                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
2011                                         $list .= "$field = ";
2012                                 }
2013                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
2014                         }
2015                 }
2016
2017                 return $list;
2018         }
2019
2020         /**
2021          * Build a partial where clause from a 2-d array such as used for LinkBatch.
2022          * The keys on each level may be either integers or strings.
2023          *
2024          * @param array $data organized as 2-d
2025          *              array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
2026          * @param string $baseKey field name to match the base-level keys to (eg 'pl_namespace')
2027          * @param string $subKey field name to match the sub-level keys to (eg 'pl_title')
2028          * @return Mixed: string SQL fragment, or false if no items in array.
2029          */
2030         public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
2031                 $conds = array();
2032
2033                 foreach ( $data as $base => $sub ) {
2034                         if ( count( $sub ) ) {
2035                                 $conds[] = $this->makeList(
2036                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
2037                                         LIST_AND );
2038                         }
2039                 }
2040
2041                 if ( $conds ) {
2042                         return $this->makeList( $conds, LIST_OR );
2043                 } else {
2044                         // Nothing to search for...
2045                         return false;
2046                 }
2047         }
2048
2049         /**
2050          * Return aggregated value alias
2051          *
2052          * @param $valuedata
2053          * @param $valuename string
2054          *
2055          * @return string
2056          */
2057         public function aggregateValue( $valuedata, $valuename = 'value' ) {
2058                 return $valuename;
2059         }
2060
2061         /**
2062          * @param $field
2063          * @return string
2064          */
2065         public function bitNot( $field ) {
2066                 return "(~$field)";
2067         }
2068
2069         /**
2070          * @param $fieldLeft
2071          * @param $fieldRight
2072          * @return string
2073          */
2074         public function bitAnd( $fieldLeft, $fieldRight ) {
2075                 return "($fieldLeft & $fieldRight)";
2076         }
2077
2078         /**
2079          * @param  $fieldLeft
2080          * @param  $fieldRight
2081          * @return string
2082          */
2083         public function bitOr( $fieldLeft, $fieldRight ) {
2084                 return "($fieldLeft | $fieldRight)";
2085         }
2086
2087         /**
2088          * Build a concatenation list to feed into a SQL query
2089          * @param array $stringList list of raw SQL expressions; caller is responsible for any quoting
2090          * @return String
2091          */
2092         public function buildConcat( $stringList ) {
2093                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
2094         }
2095
2096         /**
2097          * Build a GROUP_CONCAT or equivalent statement for a query.
2098          *
2099          * This is useful for combining a field for several rows into a single string.
2100          * NULL values will not appear in the output, duplicated values will appear,
2101          * and the resulting delimiter-separated values have no defined sort order.
2102          * Code using the results may need to use the PHP unique() or sort() methods.
2103          *
2104          * @param string $delim Glue to bind the results together
2105          * @param string|array $table Table name
2106          * @param string $field Field name
2107          * @param string|array $conds Conditions
2108          * @param string|array $join_conds Join conditions
2109          * @return String SQL text
2110          * @since 1.23
2111          */
2112         public function buildGroupConcatField(
2113                 $delim, $table, $field, $conds = '', $join_conds = array()
2114         ) {
2115                 $fld = "GROUP_CONCAT($field SEPARATOR " . $this->addQuotes( $delim ) . ')';
2116
2117                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
2118         }
2119
2120         /**
2121          * Change the current database
2122          *
2123          * @todo Explain what exactly will fail if this is not overridden.
2124          *
2125          * @param $db
2126          *
2127          * @return bool Success or failure
2128          */
2129         public function selectDB( $db ) {
2130                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
2131                 # if your database engine supports a concept similar to MySQL's
2132                 # databases you may as well.
2133                 $this->mDBname = $db;
2134
2135                 return true;
2136         }
2137
2138         /**
2139          * Get the current DB name
2140          */
2141         public function getDBname() {
2142                 return $this->mDBname;
2143         }
2144
2145         /**
2146          * Get the server hostname or IP address
2147          */
2148         public function getServer() {
2149                 return $this->mServer;
2150         }
2151
2152         /**
2153          * Format a table name ready for use in constructing an SQL query
2154          *
2155          * This does two important things: it quotes the table names to clean them up,
2156          * and it adds a table prefix if only given a table name with no quotes.
2157          *
2158          * All functions of this object which require a table name call this function
2159          * themselves. Pass the canonical name to such functions. This is only needed
2160          * when calling query() directly.
2161          *
2162          * @param string $name database table name
2163          * @param string $format One of:
2164          *   quoted - Automatically pass the table name through addIdentifierQuotes()
2165          *            so that it can be used in a query.
2166          *   raw - Do not add identifier quotes to the table name
2167          * @return String: full database name
2168          */
2169         public function tableName( $name, $format = 'quoted' ) {
2170                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
2171                 # Skip the entire process when we have a string quoted on both ends.
2172                 # Note that we check the end so that we will still quote any use of
2173                 # use of `database`.table. But won't break things if someone wants
2174                 # to query a database table with a dot in the name.
2175                 if ( $this->isQuotedIdentifier( $name ) ) {
2176                         return $name;
2177                 }
2178
2179                 # Lets test for any bits of text that should never show up in a table
2180                 # name. Basically anything like JOIN or ON which are actually part of
2181                 # SQL queries, but may end up inside of the table value to combine
2182                 # sql. Such as how the API is doing.
2183                 # Note that we use a whitespace test rather than a \b test to avoid
2184                 # any remote case where a word like on may be inside of a table name
2185                 # surrounded by symbols which may be considered word breaks.
2186                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
2187                         return $name;
2188                 }
2189
2190                 # Split database and table into proper variables.
2191                 # We reverse the explode so that database.table and table both output
2192                 # the correct table.
2193                 $dbDetails = explode( '.', $name, 2 );
2194                 if ( count( $dbDetails ) == 2 ) {
2195                         list( $database, $table ) = $dbDetails;
2196                         # We don't want any prefix added in this case
2197                         $prefix = '';
2198                 } else {
2199                         list( $table ) = $dbDetails;
2200                         if ( $wgSharedDB !== null # We have a shared database
2201                                 && $this->mForeign == false # We're not working on a foreign database
2202                                 && !$this->isQuotedIdentifier( $table ) # Prevent shared tables listing '`table`'
2203                                 && in_array( $table, $wgSharedTables ) # A shared table is selected
2204                         ) {
2205                                 $database = $wgSharedDB;
2206                                 $prefix = $wgSharedPrefix === null ? $this->mTablePrefix : $wgSharedPrefix;
2207                         } else {
2208                                 $database = null;
2209                                 $prefix = $this->mTablePrefix; # Default prefix
2210                         }
2211                 }
2212
2213                 # Quote $table and apply the prefix if not quoted.
2214                 $tableName = "{$prefix}{$table}";
2215                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $tableName ) ) {
2216                         $tableName = $this->addIdentifierQuotes( $tableName );
2217                 }
2218
2219                 # Quote $database and merge it with the table name if needed
2220                 if ( $database !== null ) {
2221                         if ( $format == 'quoted' && !$this->isQuotedIdentifier( $database ) ) {
2222                                 $database = $this->addIdentifierQuotes( $database );
2223                         }
2224                         $tableName = $database . '.' . $tableName;
2225                 }
2226
2227                 return $tableName;
2228         }
2229
2230         /**
2231          * Fetch a number of table names into an array
2232          * This is handy when you need to construct SQL for joins
2233          *
2234          * Example:
2235          * extract( $dbr->tableNames( 'user', 'watchlist' ) );
2236          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2237          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2238          *
2239          * @return array
2240          */
2241         public function tableNames() {
2242                 $inArray = func_get_args();
2243                 $retVal = array();
2244
2245                 foreach ( $inArray as $name ) {
2246                         $retVal[$name] = $this->tableName( $name );
2247                 }
2248
2249                 return $retVal;
2250         }
2251
2252         /**
2253          * Fetch a number of table names into an zero-indexed numerical array
2254          * This is handy when you need to construct SQL for joins
2255          *
2256          * Example:
2257          * list( $user, $watchlist ) = $dbr->tableNamesN( 'user', 'watchlist' );
2258          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2259          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2260          *
2261          * @return array
2262          */
2263         public function tableNamesN() {
2264                 $inArray = func_get_args();
2265                 $retVal = array();
2266
2267                 foreach ( $inArray as $name ) {
2268                         $retVal[] = $this->tableName( $name );
2269                 }
2270
2271                 return $retVal;
2272         }
2273
2274         /**
2275          * Get an aliased table name
2276          * e.g. tableName AS newTableName
2277          *
2278          * @param string $name Table name, see tableName()
2279          * @param string|bool $alias Alias (optional)
2280          * @return string SQL name for aliased table. Will not alias a table to its own name
2281          */
2282         public function tableNameWithAlias( $name, $alias = false ) {
2283                 if ( !$alias || $alias == $name ) {
2284                         return $this->tableName( $name );
2285                 } else {
2286                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2287                 }
2288         }
2289
2290         /**
2291          * Gets an array of aliased table names
2292          *
2293          * @param $tables array( [alias] => table )
2294          * @return array of strings, see tableNameWithAlias()
2295          */
2296         public function tableNamesWithAlias( $tables ) {
2297                 $retval = array();
2298                 foreach ( $tables as $alias => $table ) {
2299                         if ( is_numeric( $alias ) ) {
2300                                 $alias = $table;
2301                         }
2302                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2303                 }
2304
2305                 return $retval;
2306         }
2307
2308         /**
2309          * Get an aliased field name
2310          * e.g. fieldName AS newFieldName
2311          *
2312          * @param string $name Field name
2313          * @param string|bool $alias Alias (optional)
2314          * @return string SQL name for aliased field. Will not alias a field to its own name
2315          */
2316         public function fieldNameWithAlias( $name, $alias = false ) {
2317                 if ( !$alias || (string)$alias === (string)$name ) {
2318                         return $name;
2319                 } else {
2320                         return $name . ' AS ' . $alias; //PostgreSQL needs AS
2321                 }
2322         }
2323
2324         /**
2325          * Gets an array of aliased field names
2326          *
2327          * @param $fields array( [alias] => field )
2328          * @return array of strings, see fieldNameWithAlias()
2329          */
2330         public function fieldNamesWithAlias( $fields ) {
2331                 $retval = array();
2332                 foreach ( $fields as $alias => $field ) {
2333                         if ( is_numeric( $alias ) ) {
2334                                 $alias = $field;
2335                         }
2336                         $retval[] = $this->fieldNameWithAlias( $field, $alias );
2337                 }
2338
2339                 return $retval;
2340         }
2341
2342         /**
2343          * Get the aliased table name clause for a FROM clause
2344          * which might have a JOIN and/or USE INDEX clause
2345          *
2346          * @param array $tables ( [alias] => table )
2347          * @param $use_index array Same as for select()
2348          * @param $join_conds array Same as for select()
2349          * @return string
2350          */
2351         protected function tableNamesWithUseIndexOrJOIN(
2352                 $tables, $use_index = array(), $join_conds = array()
2353         ) {
2354                 $ret = array();
2355                 $retJOIN = array();
2356                 $use_index = (array)$use_index;
2357                 $join_conds = (array)$join_conds;
2358
2359                 foreach ( $tables as $alias => $table ) {
2360                         if ( !is_string( $alias ) ) {
2361                                 // No alias? Set it equal to the table name
2362                                 $alias = $table;
2363                         }
2364                         // Is there a JOIN clause for this table?
2365                         if ( isset( $join_conds[$alias] ) ) {
2366                                 list( $joinType, $conds ) = $join_conds[$alias];
2367                                 $tableClause = $joinType;
2368                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2369                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2370                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2371                                         if ( $use != '' ) {
2372                                                 $tableClause .= ' ' . $use;
2373                                         }
2374                                 }
2375                                 $on = $this->makeList( (array)$conds, LIST_AND );
2376                                 if ( $on != '' ) {
2377                                         $tableClause .= ' ON (' . $on . ')';
2378                                 }
2379
2380                                 $retJOIN[] = $tableClause;
2381                         // Is there an INDEX clause for this table?
2382                         } elseif ( isset( $use_index[$alias] ) ) {
2383                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2384                                 $tableClause .= ' ' . $this->useIndexClause(
2385                                         implode( ',', (array)$use_index[$alias] ) );
2386
2387                                 $ret[] = $tableClause;
2388                         } else {
2389                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2390
2391                                 $ret[] = $tableClause;
2392                         }
2393                 }
2394
2395                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2396                 $implicitJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2397                 $explicitJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2398
2399                 // Compile our final table clause
2400                 return implode( ' ', array( $implicitJoins, $explicitJoins ) );
2401         }
2402
2403         /**
2404          * Get the name of an index in a given table
2405          *
2406          * @param $index
2407          *
2408          * @return string
2409          */
2410         protected function indexName( $index ) {
2411                 // Backwards-compatibility hack
2412                 $renamed = array(
2413                         'ar_usertext_timestamp' => 'usertext_timestamp',
2414                         'un_user_id' => 'user_id',
2415                         'un_user_ip' => 'user_ip',
2416                 );
2417
2418                 if ( isset( $renamed[$index] ) ) {
2419                         return $renamed[$index];
2420                 } else {
2421                         return $index;
2422                 }
2423         }
2424
2425         /**
2426          * Adds quotes and backslashes.
2427          *
2428          * @param $s string
2429          *
2430          * @return string
2431          */
2432         public function addQuotes( $s ) {
2433                 if ( $s === null ) {
2434                         return 'NULL';
2435                 } else {
2436                         # This will also quote numeric values. This should be harmless,
2437                         # and protects against weird problems that occur when they really
2438                         # _are_ strings such as article titles and string->number->string
2439                         # conversion is not 1:1.
2440                         return "'" . $this->strencode( $s ) . "'";
2441                 }
2442         }
2443
2444         /**
2445          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2446          * MySQL uses `backticks` while basically everything else uses double quotes.
2447          * Since MySQL is the odd one out here the double quotes are our generic
2448          * and we implement backticks in DatabaseMysql.
2449          *
2450          * @param $s string
2451          *
2452          * @return string
2453          */
2454         public function addIdentifierQuotes( $s ) {
2455                 return '"' . str_replace( '"', '""', $s ) . '"';
2456         }
2457
2458         /**
2459          * Returns if the given identifier looks quoted or not according to
2460          * the database convention for quoting identifiers .
2461          *
2462          * @param $name string
2463          *
2464          * @return boolean
2465          */
2466         public function isQuotedIdentifier( $name ) {
2467                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2468         }
2469
2470         /**
2471          * @param $s string
2472          * @return string
2473          */
2474         protected function escapeLikeInternal( $s ) {
2475                 $s = str_replace( '\\', '\\\\', $s );
2476                 $s = $this->strencode( $s );
2477                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2478
2479                 return $s;
2480         }
2481
2482         /**
2483          * LIKE statement wrapper, receives a variable-length argument list with
2484          * parts of pattern to match containing either string literals that will be
2485          * escaped or tokens returned by anyChar() or anyString(). Alternatively,
2486          * the function could be provided with an array of aforementioned
2487          * parameters.
2488          *
2489          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
2490          * a LIKE clause that searches for subpages of 'My page title'.
2491          * Alternatively:
2492          *   $pattern = array( 'My_page_title/', $dbr->anyString() );
2493          *   $query .= $dbr->buildLike( $pattern );
2494          *
2495          * @since 1.16
2496          * @return String: fully built LIKE statement
2497          */
2498         public function buildLike() {
2499                 $params = func_get_args();
2500
2501                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2502                         $params = $params[0];
2503                 }
2504
2505                 $s = '';
2506
2507                 foreach ( $params as $value ) {
2508                         if ( $value instanceof LikeMatch ) {
2509                                 $s .= $value->toString();
2510                         } else {
2511                                 $s .= $this->escapeLikeInternal( $value );
2512                         }
2513                 }
2514
2515                 return " LIKE '" . $s . "' ";
2516         }
2517
2518         /**
2519          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2520          *
2521          * @return LikeMatch
2522          */
2523         public function anyChar() {
2524                 return new LikeMatch( '_' );
2525         }
2526
2527         /**
2528          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2529          *
2530          * @return LikeMatch
2531          */
2532         public function anyString() {
2533                 return new LikeMatch( '%' );
2534         }
2535
2536         /**
2537          * Returns an appropriately quoted sequence value for inserting a new row.
2538          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2539          * subclass will return an integer, and save the value for insertId()
2540          *
2541          * Any implementation of this function should *not* involve reusing
2542          * sequence numbers created for rolled-back transactions.
2543          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2544          * @param $seqName string
2545          * @return null
2546          */
2547         public function nextSequenceValue( $seqName ) {
2548                 return null;
2549         }
2550
2551         /**
2552          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2553          * is only needed because a) MySQL must be as efficient as possible due to
2554          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2555          * which index to pick.  Anyway, other databases might have different
2556          * indexes on a given table.  So don't bother overriding this unless you're
2557          * MySQL.
2558          * @param $index
2559          * @return string
2560          */
2561         public function useIndexClause( $index ) {
2562                 return '';
2563         }
2564
2565         /**
2566          * REPLACE query wrapper.
2567          *
2568          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2569          * except that when there is a duplicate key error, the old row is deleted
2570          * and the new row is inserted in its place.
2571          *
2572          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2573          * perform the delete, we need to know what the unique indexes are so that
2574          * we know how to find the conflicting rows.
2575          *
2576          * It may be more efficient to leave off unique indexes which are unlikely
2577          * to collide. However if you do this, you run the risk of encountering
2578          * errors which wouldn't have occurred in MySQL.
2579          *
2580          * @param string $table The table to replace the row(s) in.
2581          * @param array $rows Can be either a single row to insert, or multiple rows,
2582          *    in the same format as for DatabaseBase::insert()
2583          * @param array $uniqueIndexes is an array of indexes. Each element may be either
2584          *    a field name or an array of field names
2585          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2586          */
2587         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
2588                 $quotedTable = $this->tableName( $table );
2589
2590                 if ( count( $rows ) == 0 ) {
2591                         return;
2592                 }
2593
2594                 # Single row case
2595                 if ( !is_array( reset( $rows ) ) ) {
2596                         $rows = array( $rows );
2597                 }
2598
2599                 foreach ( $rows as $row ) {
2600                         # Delete rows which collide
2601                         if ( $uniqueIndexes ) {
2602                                 $sql = "DELETE FROM $quotedTable WHERE ";
2603                                 $first = true;
2604                                 foreach ( $uniqueIndexes as $index ) {
2605                                         if ( $first ) {
2606                                                 $first = false;
2607                                                 $sql .= '( ';
2608                                         } else {
2609                                                 $sql .= ' ) OR ( ';
2610                                         }
2611                                         if ( is_array( $index ) ) {
2612                                                 $first2 = true;
2613                                                 foreach ( $index as $col ) {
2614                                                         if ( $first2 ) {
2615                                                                 $first2 = false;
2616                                                         } else {
2617                                                                 $sql .= ' AND ';
2618                                                         }
2619                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2620                                                 }
2621                                         } else {
2622                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2623                                         }
2624                                 }
2625                                 $sql .= ' )';
2626                                 $this->query( $sql, $fname );
2627                         }
2628
2629                         # Now insert the row
2630                         $this->insert( $table, $row, $fname );
2631                 }
2632         }
2633
2634         /**
2635          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2636          * statement.
2637          *
2638          * @param string $table Table name
2639          * @param array $rows Rows to insert
2640          * @param string $fname Caller function name
2641          *
2642          * @return ResultWrapper
2643          */
2644         protected function nativeReplace( $table, $rows, $fname ) {
2645                 $table = $this->tableName( $table );
2646
2647                 # Single row case
2648                 if ( !is_array( reset( $rows ) ) ) {
2649                         $rows = array( $rows );
2650                 }
2651
2652                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2653                 $first = true;
2654
2655                 foreach ( $rows as $row ) {
2656                         if ( $first ) {
2657                                 $first = false;
2658                         } else {
2659                                 $sql .= ',';
2660                         }
2661
2662                         $sql .= '(' . $this->makeList( $row ) . ')';
2663                 }
2664
2665                 return $this->query( $sql, $fname );
2666         }
2667
2668         /**
2669          * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
2670          *
2671          * This updates any conflicting rows (according to the unique indexes) using
2672          * the provided SET clause and inserts any remaining (non-conflicted) rows.
2673          *
2674          * $rows may be either:
2675          *   - A single associative array. The array keys are the field names, and
2676          *     the values are the values to insert. The values are treated as data
2677          *     and will be quoted appropriately. If NULL is inserted, this will be
2678          *     converted to a database NULL.
2679          *   - An array with numeric keys, holding a list of associative arrays.
2680          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
2681          *     each subarray must be identical to each other, and in the same order.
2682          *
2683          * It may be more efficient to leave off unique indexes which are unlikely
2684          * to collide. However if you do this, you run the risk of encountering
2685          * errors which wouldn't have occurred in MySQL.
2686          *
2687          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
2688          * returns success.
2689          *
2690          * @param string $table Table name. This will be passed through DatabaseBase::tableName().
2691          * @param array $rows A single row or list of rows to insert
2692          * @param array $uniqueIndexes List of single field names or field name tuples
2693          * @param array $set An array of values to SET. For each array element,
2694          *                the key gives the field name, and the value gives the data
2695          *                to set that field to. The data will be quoted by
2696          *                DatabaseBase::addQuotes().
2697          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
2698          * @param array $options of options
2699          *
2700          * @return bool
2701          * @since 1.22
2702          */
2703         public function upsert(
2704                 $table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
2705         ) {
2706                 if ( !count( $rows ) ) {
2707                         return true; // nothing to do
2708                 }
2709                 $rows = is_array( reset( $rows ) ) ? $rows : array( $rows );
2710
2711                 if ( count( $uniqueIndexes ) ) {
2712                         $clauses = array(); // list WHERE clauses that each identify a single row
2713                         foreach ( $rows as $row ) {
2714                                 foreach ( $uniqueIndexes as $index ) {
2715                                         $index = is_array( $index ) ? $index : array( $index ); // columns
2716                                         $rowKey = array(); // unique key to this row
2717                                         foreach ( $index as $column ) {
2718                                                 $rowKey[$column] = $row[$column];
2719                                         }
2720                                         $clauses[] = $this->makeList( $rowKey, LIST_AND );
2721                                 }
2722                         }
2723                         $where = array( $this->makeList( $clauses, LIST_OR ) );
2724                 } else {
2725                         $where = false;
2726                 }
2727
2728                 $useTrx = !$this->mTrxLevel;
2729                 if ( $useTrx ) {
2730                         $this->begin( $fname );
2731                 }
2732                 try {
2733                         # Update any existing conflicting row(s)
2734                         if ( $where !== false ) {
2735                                 $ok = $this->update( $table, $set, $where, $fname );
2736                         } else {
2737                                 $ok = true;
2738                         }
2739                         # Now insert any non-conflicting row(s)
2740                         $ok = $this->insert( $table, $rows, $fname, array( 'IGNORE' ) ) && $ok;
2741                 } catch ( Exception $e ) {
2742                         if ( $useTrx ) {
2743                                 $this->rollback( $fname );
2744                         }
2745                         throw $e;
2746                 }
2747                 if ( $useTrx ) {
2748                         $this->commit( $fname );
2749                 }
2750
2751                 return $ok;
2752         }
2753
2754         /**
2755          * DELETE where the condition is a join.
2756          *
2757          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2758          * we use sub-selects
2759          *
2760          * For safety, an empty $conds will not delete everything. If you want to
2761          * delete all rows where the join condition matches, set $conds='*'.
2762          *
2763          * DO NOT put the join condition in $conds.
2764          *
2765          * @param $delTable   String: The table to delete from.
2766          * @param $joinTable  String: The other table.
2767          * @param $delVar     String: The variable to join on, in the first table.
2768          * @param $joinVar    String: The variable to join on, in the second table.
2769          * @param $conds      Array: Condition array of field names mapped to variables,
2770          *                    ANDed together in the WHERE clause
2771          * @param $fname      String: Calling function name (use __METHOD__) for
2772          *                    logs/profiling
2773          * @throws DBUnexpectedError
2774          */
2775         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2776                 $fname = __METHOD__
2777         ) {
2778                 if ( !$conds ) {
2779                         throw new DBUnexpectedError( $this,
2780                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2781                 }
2782
2783                 $delTable = $this->tableName( $delTable );
2784                 $joinTable = $this->tableName( $joinTable );
2785                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2786                 if ( $conds != '*' ) {
2787                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2788                 }
2789                 $sql .= ')';
2790
2791                 $this->query( $sql, $fname );
2792         }
2793
2794         /**
2795          * Returns the size of a text field, or -1 for "unlimited"
2796          *
2797          * @param $table string
2798          * @param $field string
2799          *
2800          * @return int
2801          */
2802         public function textFieldSize( $table, $field ) {
2803                 $table = $this->tableName( $table );
2804                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2805                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2806                 $row = $this->fetchObject( $res );
2807
2808                 $m = array();
2809
2810                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2811                         $size = $m[1];
2812                 } else {
2813                         $size = -1;
2814                 }
2815
2816                 return $size;
2817         }
2818
2819         /**
2820          * A string to insert into queries to show that they're low-priority, like
2821          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2822          * string and nothing bad should happen.
2823          *
2824          * @return string Returns the text of the low priority option if it is
2825          *   supported, or a blank string otherwise
2826          */
2827         public function lowPriorityOption() {
2828                 return '';
2829         }
2830
2831         /**
2832          * DELETE query wrapper.
2833          *
2834          * @param array $table Table name
2835          * @param string|array $conds of conditions. See $conds in DatabaseBase::select() for
2836          *               the format. Use $conds == "*" to delete all rows
2837          * @param string $fname name of the calling function
2838          *
2839          * @throws DBUnexpectedError
2840          * @return bool|ResultWrapper
2841          */
2842         public function delete( $table, $conds, $fname = __METHOD__ ) {
2843                 if ( !$conds ) {
2844                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2845                 }
2846
2847                 $table = $this->tableName( $table );
2848                 $sql = "DELETE FROM $table";
2849
2850                 if ( $conds != '*' ) {
2851                         if ( is_array( $conds ) ) {
2852                                 $conds = $this->makeList( $conds, LIST_AND );
2853                         }
2854                         $sql .= ' WHERE ' . $conds;
2855                 }
2856
2857                 return $this->query( $sql, $fname );
2858         }
2859
2860         /**
2861          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2862          * into another table.
2863          *
2864          * @param string $destTable The table name to insert into
2865          * @param string|array $srcTable May be either a table name, or an array of table names
2866          *    to include in a join.
2867          *
2868          * @param array $varMap must be an associative array of the form
2869          *    array( 'dest1' => 'source1', ...). Source items may be literals
2870          *    rather than field names, but strings should be quoted with
2871          *    DatabaseBase::addQuotes()
2872          *
2873          * @param array $conds Condition array. See $conds in DatabaseBase::select() for
2874          *    the details of the format of condition arrays. May be "*" to copy the
2875          *    whole table.
2876          *
2877          * @param string $fname The function name of the caller, from __METHOD__
2878          *
2879          * @param array $insertOptions Options for the INSERT part of the query, see
2880          *    DatabaseBase::insert() for details.
2881          * @param array $selectOptions Options for the SELECT part of the query, see
2882          *    DatabaseBase::select() for details.
2883          *
2884          * @return ResultWrapper
2885          */
2886         public function insertSelect( $destTable, $srcTable, $varMap, $conds,
2887                 $fname = __METHOD__,
2888                 $insertOptions = array(), $selectOptions = array()
2889         ) {
2890                 $destTable = $this->tableName( $destTable );
2891
2892                 if ( is_array( $insertOptions ) ) {
2893                         $insertOptions = implode( ' ', $insertOptions );
2894                 }
2895
2896                 if ( !is_array( $selectOptions ) ) {
2897                         $selectOptions = array( $selectOptions );
2898                 }
2899
2900                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2901
2902                 if ( is_array( $srcTable ) ) {
2903                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2904                 } else {
2905                         $srcTable = $this->tableName( $srcTable );
2906                 }
2907
2908                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2909                         " SELECT $startOpts " . implode( ',', $varMap ) .
2910                         " FROM $srcTable $useIndex ";
2911
2912                 if ( $conds != '*' ) {
2913                         if ( is_array( $conds ) ) {
2914                                 $conds = $this->makeList( $conds, LIST_AND );
2915                         }
2916                         $sql .= " WHERE $conds";
2917                 }
2918
2919                 $sql .= " $tailOpts";
2920
2921                 return $this->query( $sql, $fname );
2922         }
2923
2924         /**
2925          * Construct a LIMIT query with optional offset.  This is used for query
2926          * pages.  The SQL should be adjusted so that only the first $limit rows
2927          * are returned.  If $offset is provided as well, then the first $offset
2928          * rows should be discarded, and the next $limit rows should be returned.
2929          * If the result of the query is not ordered, then the rows to be returned
2930          * are theoretically arbitrary.
2931          *
2932          * $sql is expected to be a SELECT, if that makes a difference.
2933          *
2934          * The version provided by default works in MySQL and SQLite.  It will very
2935          * likely need to be overridden for most other DBMSes.
2936          *
2937          * @param string $sql SQL query we will append the limit too
2938          * @param $limit Integer the SQL limit
2939          * @param $offset Integer|bool the SQL offset (default false)
2940          *
2941          * @throws DBUnexpectedError
2942          * @return string
2943          */
2944         public function limitResult( $sql, $limit, $offset = false ) {
2945                 if ( !is_numeric( $limit ) ) {
2946                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2947                 }
2948
2949                 return "$sql LIMIT "
2950                         . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2951                         . "{$limit} ";
2952         }
2953
2954         /**
2955          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2956          * within the UNION construct.
2957          * @return Boolean
2958          */
2959         public function unionSupportsOrderAndLimit() {
2960                 return true; // True for almost every DB supported
2961         }
2962
2963         /**
2964          * Construct a UNION query
2965          * This is used for providing overload point for other DB abstractions
2966          * not compatible with the MySQL syntax.
2967          * @param array $sqls SQL statements to combine
2968          * @param $all Boolean: use UNION ALL
2969          * @return String: SQL fragment
2970          */
2971         public function unionQueries( $sqls, $all ) {
2972                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2973
2974                 return '(' . implode( $glue, $sqls ) . ')';
2975         }
2976
2977         /**
2978          * Returns an SQL expression for a simple conditional.  This doesn't need
2979          * to be overridden unless CASE isn't supported in your DBMS.
2980          *
2981          * @param string|array $cond SQL expression which will result in a boolean value
2982          * @param string $trueVal SQL expression to return if true
2983          * @param string $falseVal SQL expression to return if false
2984          * @return String: SQL fragment
2985          */
2986         public function conditional( $cond, $trueVal, $falseVal ) {
2987                 if ( is_array( $cond ) ) {
2988                         $cond = $this->makeList( $cond, LIST_AND );
2989                 }
2990
2991                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2992         }
2993
2994         /**
2995          * Returns a comand for str_replace function in SQL query.
2996          * Uses REPLACE() in MySQL
2997          *
2998          * @param string $orig column to modify
2999          * @param string $old column to seek
3000          * @param string $new column to replace with
3001          *
3002          * @return string
3003          */
3004         public function strreplace( $orig, $old, $new ) {
3005                 return "REPLACE({$orig}, {$old}, {$new})";
3006         }
3007
3008         /**
3009          * Determines how long the server has been up
3010          * STUB
3011          *
3012          * @return int
3013          */
3014         public function getServerUptime() {
3015                 return 0;
3016         }
3017
3018         /**
3019          * Determines if the last failure was due to a deadlock
3020          * STUB
3021          *
3022          * @return bool
3023          */
3024         public function wasDeadlock() {
3025                 return false;
3026         }
3027
3028         /**
3029          * Determines if the last failure was due to a lock timeout
3030          * STUB
3031          *
3032          * @return bool
3033          */
3034         public function wasLockTimeout() {
3035                 return false;
3036         }
3037
3038         /**
3039          * Determines if the last query error was something that should be dealt
3040          * with by pinging the connection and reissuing the query.
3041          * STUB
3042          *
3043          * @return bool
3044          */
3045         public function wasErrorReissuable() {
3046                 return false;
3047         }
3048
3049         /**
3050          * Determines if the last failure was due to the database being read-only.
3051          * STUB
3052          *
3053          * @return bool
3054          */
3055         public function wasReadOnlyError() {
3056                 return false;
3057         }
3058
3059         /**
3060          * Perform a deadlock-prone transaction.
3061          *
3062          * This function invokes a callback function to perform a set of write
3063          * queries. If a deadlock occurs during the processing, the transaction
3064          * will be rolled back and the callback function will be called again.
3065          *
3066          * Usage:
3067          *   $dbw->deadlockLoop( callback, ... );
3068          *
3069          * Extra arguments are passed through to the specified callback function.
3070          *
3071          * Returns whatever the callback function returned on its successful,
3072          * iteration, or false on error, for example if the retry limit was
3073          * reached.
3074          *
3075          * @return bool
3076          */
3077         public function deadlockLoop() {
3078                 $this->begin( __METHOD__ );
3079                 $args = func_get_args();
3080                 $function = array_shift( $args );
3081                 $oldIgnore = $this->ignoreErrors( true );
3082                 $tries = self::DEADLOCK_TRIES;
3083
3084                 if ( is_array( $function ) ) {
3085                         $fname = $function[0];
3086                 } else {
3087                         $fname = $function;
3088                 }
3089
3090                 do {
3091                         $retVal = call_user_func_array( $function, $args );
3092                         $error = $this->lastError();
3093                         $errno = $this->lastErrno();
3094                         $sql = $this->lastQuery();
3095
3096                         if ( $errno ) {
3097                                 if ( $this->wasDeadlock() ) {
3098                                         # Retry
3099                                         usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
3100                                 } else {
3101                                         $this->reportQueryError( $error, $errno, $sql, $fname );
3102                                 }
3103                         }
3104                 } while ( $this->wasDeadlock() && --$tries > 0 );
3105
3106                 $this->ignoreErrors( $oldIgnore );
3107
3108                 if ( $tries <= 0 ) {
3109                         $this->rollback( __METHOD__ );
3110                         $this->reportQueryError( $error, $errno, $sql, $fname );
3111
3112                         return false;
3113                 } else {
3114                         $this->commit( __METHOD__ );
3115
3116                         return $retVal;
3117                 }
3118         }
3119
3120         /**
3121          * Wait for the slave to catch up to a given master position.
3122          *
3123          * @param $pos DBMasterPos object
3124          * @param $timeout Integer: the maximum number of seconds to wait for
3125          *   synchronisation
3126          *
3127          * @return integer: zero if the slave was past that position already,
3128          *   greater than zero if we waited for some period of time, less than
3129          *   zero if we timed out.
3130          */
3131         public function masterPosWait( DBMasterPos $pos, $timeout ) {
3132                 wfProfileIn( __METHOD__ );
3133
3134                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3135                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
3136
3137                         if ( $wait > $timeout * 1e6 ) {
3138                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
3139                                 wfProfileOut( __METHOD__ );
3140
3141                                 return -1;
3142                         } elseif ( $wait > 0 ) {
3143                                 wfDebug( "Fake slave waiting $wait us\n" );
3144                                 usleep( $wait );
3145                                 wfProfileOut( __METHOD__ );
3146
3147                                 return 1;
3148                         } else {
3149                                 wfDebug( "Fake slave up to date ($wait us)\n" );
3150                                 wfProfileOut( __METHOD__ );
3151
3152                                 return 0;
3153                         }
3154                 }
3155
3156                 wfProfileOut( __METHOD__ );
3157
3158                 # Real waits are implemented in the subclass.
3159                 return 0;
3160         }
3161
3162         /**
3163          * Get the replication position of this slave
3164          *
3165          * @return DBMasterPos, or false if this is not a slave.
3166          */
3167         public function getSlavePos() {
3168                 if ( !is_null( $this->mFakeSlaveLag ) ) {
3169                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
3170                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
3171
3172                         return $pos;
3173                 } else {
3174                         # Stub
3175                         return false;
3176                 }
3177         }
3178
3179         /**
3180          * Get the position of this master
3181          *
3182          * @return DBMasterPos, or false if this is not a master
3183          */
3184         public function getMasterPos() {
3185                 if ( $this->mFakeMaster ) {
3186                         return new MySQLMasterPos( 'fake', microtime( true ) );
3187                 } else {
3188                         return false;
3189                 }
3190         }
3191
3192         /**
3193          * Run an anonymous function as soon as there is no transaction pending.
3194          * If there is a transaction and it is rolled back, then the callback is cancelled.
3195          * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
3196          * Callbacks must commit any transactions that they begin.
3197          *
3198          * This is useful for updates to different systems or when separate transactions are needed.
3199          * For example, one might want to enqueue jobs into a system outside the database, but only
3200          * after the database is updated so that the jobs will see the data when they actually run.
3201          * It can also be used for updates that easily cause deadlocks if locks are held too long.
3202          *
3203          * @param callable $callback
3204          * @since 1.20
3205          */
3206         final public function onTransactionIdle( $callback ) {
3207                 $this->mTrxIdleCallbacks[] = array( $callback, wfGetCaller() );
3208                 if ( !$this->mTrxLevel ) {
3209                         $this->runOnTransactionIdleCallbacks();
3210                 }
3211         }
3212
3213         /**
3214          * Run an anonymous function before the current transaction commits or now if there is none.
3215          * If there is a transaction and it is rolled back, then the callback is cancelled.
3216          * Callbacks must not start nor commit any transactions.
3217          *
3218          * This is useful for updates that easily cause deadlocks if locks are held too long
3219          * but where atomicity is strongly desired for these updates and some related updates.
3220          *
3221          * @param callable $callback
3222          * @since 1.22
3223          */
3224         final public function onTransactionPreCommitOrIdle( $callback ) {
3225                 if ( $this->mTrxLevel ) {
3226                         $this->mTrxPreCommitCallbacks[] = array( $callback, wfGetCaller() );
3227                 } else {
3228                         $this->onTransactionIdle( $callback ); // this will trigger immediately
3229                 }
3230         }
3231
3232         /**
3233          * Actually any "on transaction idle" callbacks.
3234          *
3235          * @since 1.20
3236          */
3237         protected function runOnTransactionIdleCallbacks() {
3238                 $autoTrx = $this->getFlag( DBO_TRX ); // automatic begin() enabled?
3239
3240                 $e = null; // last exception
3241                 do { // callbacks may add callbacks :)
3242                         $callbacks = $this->mTrxIdleCallbacks;
3243                         $this->mTrxIdleCallbacks = array(); // recursion guard
3244                         foreach ( $callbacks as $callback ) {
3245                                 try {
3246                                         list( $phpCallback ) = $callback;
3247                                         $this->clearFlag( DBO_TRX ); // make each query its own transaction
3248                                         call_user_func( $phpCallback );
3249                                         $this->setFlag( $autoTrx ? DBO_TRX : 0 ); // restore automatic begin()
3250                                 } catch ( Exception $e ) {
3251                                 }
3252                         }
3253                 } while ( count( $this->mTrxIdleCallbacks ) );
3254
3255                 if ( $e instanceof Exception ) {
3256                         throw $e; // re-throw any last exception
3257                 }
3258         }
3259
3260         /**
3261          * Actually any "on transaction pre-commit" callbacks.
3262          *
3263          * @since 1.22
3264          */
3265         protected function runOnTransactionPreCommitCallbacks() {
3266                 $e = null; // last exception
3267                 do { // callbacks may add callbacks :)
3268                         $callbacks = $this->mTrxPreCommitCallbacks;
3269                         $this->mTrxPreCommitCallbacks = array(); // recursion guard
3270                         foreach ( $callbacks as $callback ) {
3271                                 try {
3272                                         list( $phpCallback ) = $callback;
3273                                         call_user_func( $phpCallback );
3274                                 } catch ( Exception $e ) {
3275                                 }
3276                         }
3277                 } while ( count( $this->mTrxPreCommitCallbacks ) );
3278
3279                 if ( $e instanceof Exception ) {
3280                         throw $e; // re-throw any last exception
3281                 }
3282         }
3283
3284         /**
3285          * Begin an atomic section of statements
3286          *
3287          * If a transaction has been started already, just keep track of the given
3288          * section name to make sure the transaction is not committed pre-maturely.
3289          * This function can be used in layers (with sub-sections), so use a stack
3290          * to keep track of the different atomic sections. If there is no transaction,
3291          * start one implicitly.
3292          *
3293          * The goal of this function is to create an atomic section of SQL queries
3294          * without having to start a new transaction if it already exists.
3295          *
3296          * Atomic sections are more strict than transactions. With transactions,
3297          * attempting to begin a new transaction when one is already running results
3298          * in MediaWiki issuing a brief warning and doing an implicit commit. All
3299          * atomic levels *must* be explicitly closed using DatabaseBase::endAtomic(),
3300          * and any database transactions cannot be began or committed until all atomic
3301          * levels are closed. There is no such thing as implicitly opening or closing
3302          * an atomic section.
3303          *
3304          * @since 1.23
3305          * @param string $fname
3306          * @throws DBError
3307          */
3308         final public function startAtomic( $fname = __METHOD__ ) {
3309                 if ( !$this->mTrxLevel ) {
3310                         $this->begin( $fname );
3311                         $this->mTrxAutomatic = true;
3312                         $this->mTrxAutomaticAtomic = true;
3313                 }
3314
3315                 $this->mTrxAtomicLevels->push( $fname );
3316         }
3317
3318         /**
3319          * Ends an atomic section of SQL statements
3320          *
3321          * Ends the next section of atomic SQL statements and commits the transaction
3322          * if necessary.
3323          *
3324          * @since 1.23
3325          * @see DatabaseBase::startAtomic
3326          * @param string $fname
3327          * @throws DBError
3328          */
3329         final public function endAtomic( $fname = __METHOD__ ) {
3330                 if ( !$this->mTrxLevel ) {
3331                         throw new DBUnexpectedError( $this, 'No atomic transaction is open.' );
3332                 }
3333                 if ( $this->mTrxAtomicLevels->isEmpty() ||
3334                         $this->mTrxAtomicLevels->pop() !== $fname
3335                 ) {
3336                         throw new DBUnexpectedError( $this, 'Invalid atomic section ended.' );
3337                 }
3338
3339                 if ( $this->mTrxAtomicLevels->isEmpty() && $this->mTrxAutomaticAtomic ) {
3340                         $this->commit( $fname, 'flush' );
3341                 }
3342         }
3343
3344         /**
3345          * Begin a transaction. If a transaction is already in progress,
3346          * that transaction will be committed before the new transaction is started.
3347          *
3348          * Note that when the DBO_TRX flag is set (which is usually the case for web
3349          * requests, but not for maintenance scripts), any previous database query
3350          * will have started a transaction automatically.
3351          *
3352          * Nesting of transactions is not supported. Attempts to nest transactions
3353          * will cause a warning, unless the current transaction was started
3354          * automatically because of the DBO_TRX flag.
3355          *
3356          * @param $fname string
3357          * @throws DBError
3358          */
3359         final public function begin( $fname = __METHOD__ ) {
3360                 global $wgDebugDBTransactions;
3361
3362                 if ( $this->mTrxLevel ) { // implicit commit
3363                         if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3364                                 // If the current transaction was an automatic atomic one, then we definitely have
3365                                 // a problem. Same if there is any unclosed atomic level.
3366                                 throw new DBUnexpectedError( $this,
3367                                         "Attempted to start explicit transaction when atomic levels are still open."
3368                                 );
3369                         } elseif ( !$this->mTrxAutomatic ) {
3370                                 // We want to warn about inadvertently nested begin/commit pairs, but not about
3371                                 // auto-committing implicit transactions that were started by query() via DBO_TRX
3372                                 $msg = "$fname: Transaction already in progress (from {$this->mTrxFname}), " .
3373                                         " performing implicit commit!";
3374                                 wfWarn( $msg );
3375                                 wfLogDBError( $msg );
3376                         } else {
3377                                 // if the transaction was automatic and has done write operations,
3378                                 // log it if $wgDebugDBTransactions is enabled.
3379                                 if ( $this->mTrxDoneWrites && $wgDebugDBTransactions ) {
3380                                         wfDebug( "$fname: Automatic transaction with writes in progress" .
3381                                                 " (from {$this->mTrxFname}), performing implicit commit!\n"
3382                                         );
3383                                 }
3384                         }
3385
3386                         $this->runOnTransactionPreCommitCallbacks();
3387                         $this->doCommit( $fname );
3388                         if ( $this->mTrxDoneWrites ) {
3389                                 Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3390                         }
3391                         $this->runOnTransactionIdleCallbacks();
3392                 }
3393
3394                 $this->doBegin( $fname );
3395                 $this->mTrxFname = $fname;
3396                 $this->mTrxDoneWrites = false;
3397                 $this->mTrxAutomatic = false;
3398                 $this->mTrxAutomaticAtomic = false;
3399                 $this->mTrxAtomicLevels = new SplStack;
3400                 $this->mTrxIdleCallbacks = array();
3401                 $this->mTrxPreCommitCallbacks = array();
3402         }
3403
3404         /**
3405          * Issues the BEGIN command to the database server.
3406          *
3407          * @see DatabaseBase::begin()
3408          * @param type $fname
3409          */
3410         protected function doBegin( $fname ) {
3411                 $this->query( 'BEGIN', $fname );
3412                 $this->mTrxLevel = 1;
3413         }
3414
3415         /**
3416          * Commits a transaction previously started using begin().
3417          * If no transaction is in progress, a warning is issued.
3418          *
3419          * Nesting of transactions is not supported.
3420          *
3421          * @param $fname string
3422          * @param string $flush Flush flag, set to 'flush' to disable warnings about
3423          *   explicitly committing implicit transactions, or calling commit when no
3424          *   transaction is in progress. This will silently break any ongoing
3425          *   explicit transaction. Only set the flush flag if you are sure that it
3426          *   is safe to ignore these warnings in your context.
3427          */
3428         final public function commit( $fname = __METHOD__, $flush = '' ) {
3429                 if ( !$this->mTrxAtomicLevels->isEmpty() ) {
3430                         // There are still atomic sections open. This cannot be ignored
3431                         throw new DBUnexpectedError(
3432                                 $this,
3433                                 "Attempted to commit transaction while atomic sections are still open"
3434                         );
3435                 }
3436
3437                 if ( $flush != 'flush' ) {
3438                         if ( !$this->mTrxLevel ) {
3439                                 wfWarn( "$fname: No transaction to commit, something got out of sync!" );
3440                         } elseif ( $this->mTrxAutomatic ) {
3441                                 wfWarn( "$fname: Explicit commit of implicit transaction. Something may be out of sync!" );
3442                         }
3443                 } else {
3444                         if ( !$this->mTrxLevel ) {
3445                                 return; // nothing to do
3446                         } elseif ( !$this->mTrxAutomatic ) {
3447                                 wfWarn( "$fname: Flushing an explicit transaction, getting out of sync!" );
3448                         }
3449                 }
3450
3451                 $this->runOnTransactionPreCommitCallbacks();
3452                 $this->doCommit( $fname );
3453                 if ( $this->mTrxDoneWrites ) {
3454                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3455                 }
3456                 $this->runOnTransactionIdleCallbacks();
3457         }
3458
3459         /**
3460          * Issues the COMMIT command to the database server.
3461          *
3462          * @see DatabaseBase::commit()
3463          * @param type $fname
3464          */
3465         protected function doCommit( $fname ) {
3466                 if ( $this->mTrxLevel ) {
3467                         $this->query( 'COMMIT', $fname );
3468                         $this->mTrxLevel = 0;
3469                 }
3470         }
3471
3472         /**
3473          * Rollback a transaction previously started using begin().
3474          * If no transaction is in progress, a warning is issued.
3475          *
3476          * No-op on non-transactional databases.
3477          *
3478          * @param $fname string
3479          */
3480         final public function rollback( $fname = __METHOD__ ) {
3481                 if ( !$this->mTrxLevel ) {
3482                         wfWarn( "$fname: No transaction to rollback, something got out of sync!" );
3483                 }
3484                 $this->doRollback( $fname );
3485                 $this->mTrxIdleCallbacks = array(); // cancel
3486                 $this->mTrxPreCommitCallbacks = array(); // cancel
3487                 $this->mTrxAtomicLevels = new SplStack;
3488                 if ( $this->mTrxDoneWrites ) {
3489                         Profiler::instance()->transactionWritingOut( $this->mServer, $this->mDBname );
3490                 }
3491         }
3492
3493         /**
3494          * Issues the ROLLBACK command to the database server.
3495          *
3496          * @see DatabaseBase::rollback()
3497          * @param type $fname
3498          */
3499         protected function doRollback( $fname ) {
3500                 if ( $this->mTrxLevel ) {
3501                         $this->query( 'ROLLBACK', $fname, true );
3502                         $this->mTrxLevel = 0;
3503                 }
3504         }
3505
3506         /**
3507          * Creates a new table with structure copied from existing table
3508          * Note that unlike most database abstraction functions, this function does not
3509          * automatically append database prefix, because it works at a lower
3510          * abstraction level.
3511          * The table names passed to this function shall not be quoted (this
3512          * function calls addIdentifierQuotes when needed).
3513          *
3514          * @param string $oldName name of table whose structure should be copied
3515          * @param string $newName name of table to be created
3516          * @param $temporary Boolean: whether the new table should be temporary
3517          * @param string $fname calling function name
3518          * @throws MWException
3519          * @return Boolean: true if operation was successful
3520          */
3521         public function duplicateTableStructure( $oldName, $newName, $temporary = false,
3522                 $fname = __METHOD__
3523         ) {
3524                 throw new MWException(
3525                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
3526         }
3527
3528         /**
3529          * List all tables on the database
3530          *
3531          * @param string $prefix Only show tables with this prefix, e.g. mw_
3532          * @param string $fname calling function name
3533          * @throws MWException
3534          */
3535         function listTables( $prefix = null, $fname = __METHOD__ ) {
3536                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
3537         }
3538
3539         /**
3540          * Reset the views process cache set by listViews()
3541          * @since 1.22
3542          */
3543         final public function clearViewsCache() {
3544                 $this->allViews = null;
3545         }
3546
3547         /**
3548          * Lists all the VIEWs in the database
3549          *
3550          * For caching purposes the list of all views should be stored in
3551          * $this->allViews. The process cache can be cleared with clearViewsCache()
3552          *
3553          * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
3554          * @param string $fname Name of calling function
3555          * @throws MWException
3556          * @since 1.22
3557          */
3558         public function listViews( $prefix = null, $fname = __METHOD__ ) {
3559                 throw new MWException( 'DatabaseBase::listViews is not implemented in descendant class' );
3560         }
3561
3562         /**
3563          * Differentiates between a TABLE and a VIEW
3564          *
3565          * @param $name string: Name of the database-structure to test.
3566          * @throws MWException
3567          * @since 1.22
3568          */
3569         public function isView( $name ) {
3570                 throw new MWException( 'DatabaseBase::isView is not implemented in descendant class' );
3571         }
3572
3573         /**
3574          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3575          * to the format used for inserting into timestamp fields in this DBMS.
3576          *
3577          * The result is unquoted, and needs to be passed through addQuotes()
3578          * before it can be included in raw SQL.
3579          *
3580          * @param $ts string|int
3581          *
3582          * @return string
3583          */
3584         public function timestamp( $ts = 0 ) {
3585                 return wfTimestamp( TS_MW, $ts );
3586         }
3587
3588         /**
3589          * Convert a timestamp in one of the formats accepted by wfTimestamp()
3590          * to the format used for inserting into timestamp fields in this DBMS. If
3591          * NULL is input, it is passed through, allowing NULL values to be inserted
3592          * into timestamp fields.
3593          *
3594          * The result is unquoted, and needs to be passed through addQuotes()
3595          * before it can be included in raw SQL.
3596          *
3597          * @param $ts string|int
3598          *
3599          * @return string
3600          */
3601         public function timestampOrNull( $ts = null ) {
3602                 if ( is_null( $ts ) ) {
3603                         return null;
3604                 } else {
3605                         return $this->timestamp( $ts );
3606                 }
3607         }
3608
3609         /**
3610          * Take the result from a query, and wrap it in a ResultWrapper if
3611          * necessary. Boolean values are passed through as is, to indicate success
3612          * of write queries or failure.
3613          *
3614          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
3615          * resource, and it was necessary to call this function to convert it to
3616          * a wrapper. Nowadays, raw database objects are never exposed to external
3617          * callers, so this is unnecessary in external code. For compatibility with
3618          * old code, ResultWrapper objects are passed through unaltered.
3619          *
3620          * @param $result bool|ResultWrapper
3621          *
3622          * @return bool|ResultWrapper
3623          */
3624         public function resultObject( $result ) {
3625                 if ( empty( $result ) ) {
3626                         return false;
3627                 } elseif ( $result instanceof ResultWrapper ) {
3628                         return $result;
3629                 } elseif ( $result === true ) {
3630                         // Successful write query
3631                         return $result;
3632                 } else {
3633                         return new ResultWrapper( $this, $result );
3634                 }
3635         }
3636
3637         /**
3638          * Ping the server and try to reconnect if it there is no connection
3639          *
3640          * @return bool Success or failure
3641          */
3642         public function ping() {
3643                 # Stub.  Not essential to override.
3644                 return true;
3645         }
3646
3647         /**
3648          * Get slave lag. Currently supported only by MySQL.
3649          *
3650          * Note that this function will generate a fatal error on many
3651          * installations. Most callers should use LoadBalancer::safeGetLag()
3652          * instead.
3653          *
3654          * @return int Database replication lag in seconds
3655          */
3656         public function getLag() {
3657                 return intval( $this->mFakeSlaveLag );
3658         }
3659
3660         /**
3661          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3662          *
3663          * @return int
3664          */
3665         function maxListLen() {
3666                 return 0;
3667         }
3668
3669         /**
3670          * Some DBMSs have a special format for inserting into blob fields, they
3671          * don't allow simple quoted strings to be inserted. To insert into such
3672          * a field, pass the data through this function before passing it to
3673          * DatabaseBase::insert().
3674          * @param $b string
3675          * @return string
3676          */
3677         public function encodeBlob( $b ) {
3678                 return $b;
3679         }
3680
3681         /**
3682          * Some DBMSs return a special placeholder object representing blob fields
3683          * in result objects. Pass the object through this function to return the
3684          * original string.
3685          * @param $b string
3686          * @return string
3687          */
3688         public function decodeBlob( $b ) {
3689                 return $b;
3690         }
3691
3692         /**
3693          * Override database's default behavior. $options include:
3694          *     'connTimeout' : Set the connection timeout value in seconds.
3695          *                     May be useful for very long batch queries such as
3696          *                     full-wiki dumps, where a single query reads out over
3697          *                     hours or days.
3698          *
3699          * @param $options Array
3700          * @return void
3701          */
3702         public function setSessionOptions( array $options ) {
3703         }
3704
3705         /**
3706          * Read and execute SQL commands from a file.
3707          *
3708          * Returns true on success, error string or exception on failure (depending
3709          * on object's error ignore settings).
3710          *
3711          * @param string $filename File name to open
3712          * @param bool|callable $lineCallback Optional function called before reading each line
3713          * @param bool|callable $resultCallback Optional function called for each MySQL result
3714          * @param bool|string $fname Calling function name or false if name should be
3715          *   generated dynamically using $filename
3716          * @param bool|callable $inputCallback Callback: Optional function called
3717          *   for each complete line sent
3718          * @throws MWException
3719          * @throws Exception|MWException
3720          * @return bool|string
3721          */
3722         public function sourceFile(
3723                 $filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
3724         ) {
3725                 wfSuppressWarnings();
3726                 $fp = fopen( $filename, 'r' );
3727                 wfRestoreWarnings();
3728
3729                 if ( false === $fp ) {
3730                         throw new MWException( "Could not open \"{$filename}\".\n" );
3731                 }
3732
3733                 if ( !$fname ) {
3734                         $fname = __METHOD__ . "( $filename )";
3735                 }
3736
3737                 try {
3738                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname, $inputCallback );
3739                 } catch ( MWException $e ) {
3740                         fclose( $fp );
3741                         throw $e;
3742                 }
3743
3744                 fclose( $fp );
3745
3746                 return $error;
3747         }
3748
3749         /**
3750          * Get the full path of a patch file. Originally based on archive()
3751          * from updaters.inc. Keep in mind this always returns a patch, as
3752          * it fails back to MySQL if no DB-specific patch can be found
3753          *
3754          * @param string $patch The name of the patch, like patch-something.sql
3755          * @return String Full path to patch file
3756          */
3757         public function patchPath( $patch ) {
3758                 global $IP;
3759
3760                 $dbType = $this->getType();
3761                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3762                         return "$IP/maintenance/$dbType/archives/$patch";
3763                 } else {
3764                         return "$IP/maintenance/archives/$patch";
3765                 }
3766         }
3767
3768         /**
3769          * Set variables to be used in sourceFile/sourceStream, in preference to the
3770          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3771          * all. If it's set to false, $GLOBALS will be used.
3772          *
3773          * @param bool|array $vars mapping variable name to value.
3774          */
3775         public function setSchemaVars( $vars ) {
3776                 $this->mSchemaVars = $vars;
3777         }
3778
3779         /**
3780          * Read and execute commands from an open file handle.
3781          *
3782          * Returns true on success, error string or exception on failure (depending
3783          * on object's error ignore settings).
3784          *
3785          * @param $fp Resource: File handle
3786          * @param $lineCallback Callback: Optional function called before reading each query
3787          * @param $resultCallback Callback: Optional function called for each MySQL result
3788          * @param string $fname Calling function name
3789          * @param $inputCallback Callback: Optional function called for each complete query sent
3790          * @return bool|string
3791          */
3792         public function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3793                 $fname = __METHOD__, $inputCallback = false
3794         ) {
3795                 $cmd = '';
3796
3797                 while ( !feof( $fp ) ) {
3798                         if ( $lineCallback ) {
3799                                 call_user_func( $lineCallback );
3800                         }
3801
3802                         $line = trim( fgets( $fp ) );
3803
3804                         if ( $line == '' ) {
3805                                 continue;
3806                         }
3807
3808                         if ( '-' == $line[0] && '-' == $line[1] ) {
3809                                 continue;
3810                         }
3811
3812                         if ( $cmd != '' ) {
3813                                 $cmd .= ' ';
3814                         }
3815
3816                         $done = $this->streamStatementEnd( $cmd, $line );
3817
3818                         $cmd .= "$line\n";
3819
3820                         if ( $done || feof( $fp ) ) {
3821                                 $cmd = $this->replaceVars( $cmd );
3822
3823                                 if ( ( $inputCallback && call_user_func( $inputCallback, $cmd ) ) || !$inputCallback ) {
3824                                         $res = $this->query( $cmd, $fname );
3825
3826                                         if ( $resultCallback ) {
3827                                                 call_user_func( $resultCallback, $res, $this );
3828                                         }
3829
3830                                         if ( false === $res ) {
3831                                                 $err = $this->lastError();
3832
3833                                                 return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3834                                         }
3835                                 }
3836                                 $cmd = '';
3837                         }
3838                 }
3839
3840                 return true;
3841         }
3842
3843         /**
3844          * Called by sourceStream() to check if we've reached a statement end
3845          *
3846          * @param string $sql SQL assembled so far
3847          * @param string $newLine New line about to be added to $sql
3848          * @return Bool Whether $newLine contains end of the statement
3849          */
3850         public function streamStatementEnd( &$sql, &$newLine ) {
3851                 if ( $this->delimiter ) {
3852                         $prev = $newLine;
3853                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3854                         if ( $newLine != $prev ) {
3855                                 return true;
3856                         }
3857                 }
3858
3859                 return false;
3860         }
3861
3862         /**
3863          * Database independent variable replacement. Replaces a set of variables
3864          * in an SQL statement with their contents as given by $this->getSchemaVars().
3865          *
3866          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3867          *
3868          * - '{$var}' should be used for text and is passed through the database's
3869          *   addQuotes method.
3870          * - `{$var}` should be used for identifiers (eg: table and database names),
3871          *   it is passed through the database's addIdentifierQuotes method which
3872          *   can be overridden if the database uses something other than backticks.
3873          * - / *$var* / is just encoded, besides traditional table prefix and
3874          *   table options its use should be avoided.
3875          *
3876          * @param string $ins SQL statement to replace variables in
3877          * @return String The new SQL statement with variables replaced
3878          */
3879         protected function replaceSchemaVars( $ins ) {
3880                 $vars = $this->getSchemaVars();
3881                 foreach ( $vars as $var => $value ) {
3882                         // replace '{$var}'
3883                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3884                         // replace `{$var}`
3885                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3886                         // replace /*$var*/
3887                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ), $ins );
3888                 }
3889
3890                 return $ins;
3891         }
3892
3893         /**
3894          * Replace variables in sourced SQL
3895          *
3896          * @param $ins string
3897          *
3898          * @return string
3899          */
3900         protected function replaceVars( $ins ) {
3901                 $ins = $this->replaceSchemaVars( $ins );
3902
3903                 // Table prefixes
3904                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3905                         array( $this, 'tableNameCallback' ), $ins );
3906
3907                 // Index names
3908                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3909                         array( $this, 'indexNameCallback' ), $ins );
3910
3911                 return $ins;
3912         }
3913
3914         /**
3915          * Get schema variables. If none have been set via setSchemaVars(), then
3916          * use some defaults from the current object.
3917          *
3918          * @return array
3919          */
3920         protected function getSchemaVars() {
3921                 if ( $this->mSchemaVars ) {
3922                         return $this->mSchemaVars;
3923                 } else {
3924                         return $this->getDefaultSchemaVars();
3925                 }
3926         }
3927
3928         /**
3929          * Get schema variables to use if none have been set via setSchemaVars().
3930          *
3931          * Override this in derived classes to provide variables for tables.sql
3932          * and SQL patch files.
3933          *
3934          * @return array
3935          */
3936         protected function getDefaultSchemaVars() {
3937                 return array();
3938         }
3939
3940         /**
3941          * Table name callback
3942          *
3943          * @param $matches array
3944          *
3945          * @return string
3946          */
3947         protected function tableNameCallback( $matches ) {
3948                 return $this->tableName( $matches[1] );
3949         }
3950
3951         /**
3952          * Index name callback
3953          *
3954          * @param $matches array
3955          *
3956          * @return string
3957          */
3958         protected function indexNameCallback( $matches ) {
3959                 return $this->indexName( $matches[1] );
3960         }
3961
3962         /**
3963          * Check to see if a named lock is available. This is non-blocking.
3964          *
3965          * @param string $lockName name of lock to poll
3966          * @param string $method name of method calling us
3967          * @return Boolean
3968          * @since 1.20
3969          */
3970         public function lockIsFree( $lockName, $method ) {
3971                 return true;
3972         }
3973
3974         /**
3975          * Acquire a named lock
3976          *
3977          * Abstracted from Filestore::lock() so child classes can implement for
3978          * their own needs.
3979          *
3980          * @param string $lockName name of lock to aquire
3981          * @param string $method name of method calling us
3982          * @param $timeout Integer: timeout
3983          * @return Boolean
3984          */
3985         public function lock( $lockName, $method, $timeout = 5 ) {
3986                 return true;
3987         }
3988
3989         /**
3990          * Release a lock.
3991          *
3992          * @param string $lockName Name of lock to release
3993          * @param string $method Name of method calling us
3994          *
3995          * @return int Returns 1 if the lock was released, 0 if the lock was not established
3996          * by this thread (in which case the lock is not released), and NULL if the named
3997          * lock did not exist
3998          */
3999         public function unlock( $lockName, $method ) {
4000                 return true;
4001         }
4002
4003         /**
4004          * Lock specific tables
4005          *
4006          * @param array $read of tables to lock for read access
4007          * @param array $write of tables to lock for write access
4008          * @param string $method name of caller
4009          * @param bool $lowPriority Whether to indicate writes to be LOW PRIORITY
4010          *
4011          * @return bool
4012          */
4013         public function lockTables( $read, $write, $method, $lowPriority = true ) {
4014                 return true;
4015         }
4016
4017         /**
4018          * Unlock specific tables
4019          *
4020          * @param string $method the caller
4021          *
4022          * @return bool
4023          */
4024         public function unlockTables( $method ) {
4025                 return true;
4026         }
4027
4028         /**
4029          * Delete a table
4030          * @param $tableName string
4031          * @param $fName string
4032          * @return bool|ResultWrapper
4033          * @since 1.18
4034          */
4035         public function dropTable( $tableName, $fName = __METHOD__ ) {
4036                 if ( !$this->tableExists( $tableName, $fName ) ) {
4037                         return false;
4038                 }
4039                 $sql = "DROP TABLE " . $this->tableName( $tableName );
4040                 if ( $this->cascadingDeletes() ) {
4041                         $sql .= " CASCADE";
4042                 }
4043
4044                 return $this->query( $sql, $fName );
4045         }
4046
4047         /**
4048          * Get search engine class. All subclasses of this need to implement this
4049          * if they wish to use searching.
4050          *
4051          * @return String
4052          */
4053         public function getSearchEngine() {
4054                 return 'SearchEngineDummy';
4055         }
4056
4057         /**
4058          * Find out when 'infinity' is. Most DBMSes support this. This is a special
4059          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
4060          * because "i" sorts after all numbers.
4061          *
4062          * @return String
4063          */
4064         public function getInfinity() {
4065                 return 'infinity';
4066         }
4067
4068         /**
4069          * Encode an expiry time into the DBMS dependent format
4070          *
4071          * @param string $expiry timestamp for expiry, or the 'infinity' string
4072          * @return String
4073          */
4074         public function encodeExpiry( $expiry ) {
4075                 return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
4076                         ? $this->getInfinity()
4077                         : $this->timestamp( $expiry );
4078         }
4079
4080         /**
4081          * Decode an expiry time into a DBMS independent format
4082          *
4083          * @param string $expiry DB timestamp field value for expiry
4084          * @param $format integer: TS_* constant, defaults to TS_MW
4085          * @return String
4086          */
4087         public function decodeExpiry( $expiry, $format = TS_MW ) {
4088                 return ( $expiry == '' || $expiry == $this->getInfinity() )
4089                         ? 'infinity'
4090                         : wfTimestamp( $format, $expiry );
4091         }
4092
4093         /**
4094          * Allow or deny "big selects" for this session only. This is done by setting
4095          * the sql_big_selects session variable.
4096          *
4097          * This is a MySQL-specific feature.
4098          *
4099          * @param $value Mixed: true for allow, false for deny, or "default" to
4100          *   restore the initial value
4101          */
4102         public function setBigSelects( $value = true ) {
4103                 // no-op
4104         }
4105
4106         /**
4107          * @since 1.19
4108          */
4109         public function __toString() {
4110                 return (string)$this->mConn;
4111         }
4112
4113         /**
4114          * Run a few simple sanity checks
4115          */
4116         public function __destruct() {
4117                 if ( $this->mTrxLevel && $this->mTrxDoneWrites ) {
4118                         trigger_error( "Uncommitted DB writes (transaction from {$this->mTrxFname})." );
4119                 }
4120                 if ( count( $this->mTrxIdleCallbacks ) || count( $this->mTrxPreCommitCallbacks ) ) {
4121                         $callers = array();
4122                         foreach ( $this->mTrxIdleCallbacks as $callbackInfo ) {
4123                                 $callers[] = $callbackInfo[1];
4124                         }
4125                         $callers = implode( ', ', $callers );
4126                         trigger_error( "DB transaction callbacks still pending (from $callers)." );
4127                 }
4128         }
4129 }