includes/db/Database.php

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