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