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