includes/db/Database.php

   1 <?php
   2 /**
   3  * @defgroup Database Database
   4  *
   5  * @file
   6  * @ingroup Database
   7  * This file deals with database interface functions
   8  * and query specifics/optimisations
   9  */
  10
  11 /** Number of times to re-try an operation in case of deadlock */
  12 define( 'DEADLOCK_TRIES', 4 );
  13 /** Minimum time to wait before retry, in microseconds */
  14 define( 'DEADLOCK_DELAY_MIN', 500000 );
  15 /** Maximum time to wait before retry */
  16 define( 'DEADLOCK_DELAY_MAX', 1500000 );
  17
  18 /**
  19  * Base interface for all DBMS-specific code. At a bare minimum, all of the
  20  * following must be implemented to support MediaWiki
  21  *
  22  * @file
  23  * @ingroup Database
  24  */
  25 interface DatabaseType {
  26         /**
  27          * Get the type of the DBMS, as it appears in $wgDBtype.
  28          *
  29          * @return string
  30          */
  31         function getType();
  32
  33         /**
  34          * Open a connection to the database. Usually aborts on failure
  35          *
  36          * @param $server String: database server host
  37          * @param $user String: database user name
  38          * @param $password String: database user password
  39          * @param $dbName String: database name
  40          * @return bool
  41          * @throws DBConnectionError
  42          */
  43         function open( $server, $user, $password, $dbName );
  44
  45         /**
  46          * Fetch the next row from the given result object, in object form.
  47          * Fields can be retrieved with $row->fieldname, with fields acting like
  48          * member variables.
  49          *
  50          * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
  51          * @return Row object
  52          * @throws DBUnexpectedError Thrown if the database returns an error
  53          */
  54         function fetchObject( $res );
  55
  56         /**
  57          * Fetch the next row from the given result object, in associative array
  58          * form.  Fields are retrieved with $row['fieldname'].
  59          *
  60          * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
  61          * @return Row object
  62          * @throws DBUnexpectedError Thrown if the database returns an error
  63          */
  64         function fetchRow( $res );
  65
  66         /**
  67          * Get the number of rows in a result object
  68          *
  69          * @param $res Mixed: A SQL result
  70          * @return int
  71          */
  72         function numRows( $res );
  73
  74         /**
  75          * Get the number of fields in a result object
  76          * @see http://www.php.net/mysql_num_fields
  77          *
  78          * @param $res Mixed: A SQL result
  79          * @return int
  80          */
  81         function numFields( $res );
  82
  83         /**
  84          * Get a field name in a result object
  85          * @see http://www.php.net/mysql_field_name
  86          *
  87          * @param $res Mixed: A SQL result
  88          * @param $n Integer
  89          * @return string
  90          */
  91         function fieldName( $res, $n );
  92
  93         /**
  94          * Get the inserted value of an auto-increment row
  95          *
  96          * The value inserted should be fetched from nextSequenceValue()
  97          *
  98          * Example:
  99          * $id = $dbw->nextSequenceValue('page_page_id_seq');
 100          * $dbw->insert('page',array('page_id' => $id));
 101          * $id = $dbw->insertId();
 102          *
 103          * @return int
 104          */
 105         function insertId();
 106
 107         /**
 108          * Change the position of the cursor in a result object
 109          * @see http://www.php.net/mysql_data_seek
 110          *
 111          * @param $res Mixed: A SQL result
 112          * @param $row Mixed: Either MySQL row or ResultWrapper
 113          */
 114         function dataSeek( $res, $row );
 115
 116         /**
 117          * Get the last error number
 118          * @see http://www.php.net/mysql_errno
 119          *
 120          * @return int
 121          */
 122         function lastErrno();
 123
 124         /**
 125          * Get a description of the last error
 126          * @see http://www.php.net/mysql_error
 127          *
 128          * @return string
 129          */
 130         function lastError();
 131
 132         /**
 133          * mysql_fetch_field() wrapper
 134          * Returns false if the field doesn't exist
 135          *
 136          * @param $table string: table name
 137          * @param $field string: field name
 138          *
 139          * @return Field
 140          */
 141         function fieldInfo( $table, $field );
 142
 143         /**
 144          * Get information about an index into an object
 145          * @param $table string: Table name
 146          * @param $index string: Index name
 147          * @param $fname string: Calling function name
 148          * @return Mixed: Database-specific index description class or false if the index does not exist
 149          */
 150         function indexInfo( $table, $index, $fname = 'Database::indexInfo' );
 151
 152         /**
 153          * Get the number of rows affected by the last write query
 154          * @see http://www.php.net/mysql_affected_rows
 155          *
 156          * @return int
 157          */
 158         function affectedRows();
 159
 160         /**
 161          * Wrapper for addslashes()
 162          *
 163          * @param $s string: to be slashed.
 164          * @return string: slashed string.
 165          */
 166         function strencode( $s );
 167
 168         /**
 169          * Returns a wikitext link to the DB's website, e.g.,
 170          *     return "[http://www.mysql.com/ MySQL]";
 171          * Should at least contain plain text, if for some reason
 172          * your database has no website.
 173          *
 174          * @return string: wikitext of a link to the server software's web site
 175          */
 176         static function getSoftwareLink();
 177
 178         /**
 179          * A string describing the current software version, like from
 180          * mysql_get_server_info().
 181          *
 182          * @return string: Version information from the database server.
 183          */
 184         function getServerVersion();
 185
 186         /**
 187          * A string describing the current software version, and possibly
 188          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 189          * Use getServerVersion() to get machine-friendly information.
 190          *
 191          * @return string: Version information from the database server
 192          */
 193         function getServerInfo();
 194 }
 195
 196 /**
 197  * Database abstraction object
 198  * @ingroup Database
 199  */
 200 abstract class DatabaseBase implements DatabaseType {
 201
 202 # ------------------------------------------------------------------------------
 203 # Variables
 204 # ------------------------------------------------------------------------------
 205
 206         protected $mLastQuery = '';
 207         protected $mDoneWrites = false;
 208         protected $mPHPError = false;
 209
 210         protected $mServer, $mUser, $mPassword, $mDBname;
 211
 212         /**
 213          * @var DatabaseBase
 214          */
 215         protected $mConn = null;
 216         protected $mOpened = false;
 217
 218         protected $mTablePrefix;
 219         protected $mFlags;
 220         protected $mTrxLevel = 0;
 221         protected $mErrorCount = 0;
 222         protected $mLBInfo = array();
 223         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 224         protected $mDefaultBigSelects = null;
 225         protected $mSchemaVars = false;
 226
 227         protected $preparedArgs;
 228
 229         protected $htmlErrors;
 230
 231         protected $delimiter = ';';
 232
 233 # ------------------------------------------------------------------------------
 234 # Accessors
 235 # ------------------------------------------------------------------------------
 236         # These optionally set a variable and return the previous state
 237
 238         /**
 239          * A string describing the current software version, and possibly
 240          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 241          * Use getServerVersion() to get machine-friendly information.
 242          *
 243          * @return string: Version information from the database server
 244          */
 245         public function getServerInfo() {
 246                 return $this->getServerVersion();
 247         }
 248
 249         /**
 250          * Boolean, controls output of large amounts of debug information.
 251          * @param $debug bool|null
 252          *   - true to enable debugging
 253          *   - false to disable debugging
 254          *   - omitted or null to do nothing
 255          *
 256          * @return The previous value of the flag
 257          */
 258         function debug( $debug = null ) {
 259                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 260         }
 261
 262         /**
 263          * Turns buffering of SQL result sets on (true) or off (false). Default is
 264          * "on".
 265          *
 266          * Unbuffered queries are very troublesome in MySQL:
 267          *
 268          *   - If another query is executed while the first query is being read
 269          *     out, the first query is killed. This means you can't call normal
 270          *     MediaWiki functions while you are reading an unbuffered query result
 271          *     from a normal wfGetDB() connection.
 272          *
 273          *   - Unbuffered queries cause the MySQL server to use large amounts of
 274          *     memory and to hold broad locks which block other queries.
 275          *
 276          * If you want to limit client-side memory, it's almost always better to
 277          * split up queries into batches using a LIMIT clause than to switch off
 278          * buffering.
 279          *
 280          * @param $buffer null|bool
 281          *
 282          * @return The previous value of the flag
 283          */
 284         function bufferResults( $buffer = null ) {
 285                 if ( is_null( $buffer ) ) {
 286                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 287                 } else {
 288                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 289                 }
 290         }
 291
 292         /**
 293          * Turns on (false) or off (true) the automatic generation and sending
 294          * of a "we're sorry, but there has been a database error" page on
 295          * database errors. Default is on (false). When turned off, the
 296          * code should use lastErrno() and lastError() to handle the
 297          * situation as appropriate.
 298          *
 299          * @param $ignoreErrors bool|null
 300          *
 301          * @return bool The previous value of the flag.
 302          */
 303         function ignoreErrors( $ignoreErrors = null ) {
 304                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 305         }
 306
 307         /**
 308          * Gets or sets the current transaction level.
 309          *
 310          * Historically, transactions were allowed to be "nested". This is no
 311          * longer supported, so this function really only returns a boolean.
 312          *
 313          * @param $level An integer (0 or 1), or omitted to leave it unchanged.
 314          * @return The previous value
 315          */
 316         function trxLevel( $level = null ) {
 317                 return wfSetVar( $this->mTrxLevel, $level );
 318         }
 319
 320         /**
 321          * Get/set the number of errors logged. Only useful when errors are ignored
 322          * @param $count The count to set, or omitted to leave it unchanged.
 323          * @return The error count
 324          */
 325         function errorCount( $count = null ) {
 326                 return wfSetVar( $this->mErrorCount, $count );
 327         }
 328
 329         /**
 330          * Get/set the table prefix.
 331          * @param $prefix The table prefix to set, or omitted to leave it unchanged.
 332          * @return The previous table prefix.
 333          */
 334         function tablePrefix( $prefix = null ) {
 335                 return wfSetVar( $this->mTablePrefix, $prefix );
 336         }
 337
 338         /**
 339          * Get properties passed down from the server info array of the load
 340          * balancer.
 341          *
 342          * @param $name string The entry of the info array to get, or null to get the
 343          *   whole array
 344          *
 345          * @return LoadBalancer|null
 346          */
 347         function getLBInfo( $name = null ) {
 348                 if ( is_null( $name ) ) {
 349                         return $this->mLBInfo;
 350                 } else {
 351                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 352                                 return $this->mLBInfo[$name];
 353                         } else {
 354                                 return null;
 355                         }
 356                 }
 357         }
 358
 359         /**
 360          * Set the LB info array, or a member of it. If called with one parameter,
 361          * the LB info array is set to that parameter. If it is called with two
 362          * parameters, the member with the given name is set to the given value.
 363          *
 364          * @param $name
 365          * @param $value
 366          */
 367         function setLBInfo( $name, $value = null ) {
 368                 if ( is_null( $value ) ) {
 369                         $this->mLBInfo = $name;
 370                 } else {
 371                         $this->mLBInfo[$name] = $value;
 372                 }
 373         }
 374
 375         /**
 376          * Set lag time in seconds for a fake slave
 377          *
 378          * @param $lag int
 379          */
 380         function setFakeSlaveLag( $lag ) {
 381                 $this->mFakeSlaveLag = $lag;
 382         }
 383
 384         /**
 385          * Make this connection a fake master
 386          *
 387          * @param $enabled bool
 388          */
 389         function setFakeMaster( $enabled = true ) {
 390                 $this->mFakeMaster = $enabled;
 391         }
 392
 393         /**
 394          * Returns true if this database supports (and uses) cascading deletes
 395          *
 396          * @return bool
 397          */
 398         function cascadingDeletes() {
 399                 return false;
 400         }
 401
 402         /**
 403          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 404          *
 405          * @return bool
 406          */
 407         function cleanupTriggers() {
 408                 return false;
 409         }
 410
 411         /**
 412          * Returns true if this database is strict about what can be put into an IP field.
 413          * Specifically, it uses a NULL value instead of an empty string.
 414          *
 415          * @return bool
 416          */
 417         function strictIPs() {
 418                 return false;
 419         }
 420
 421         /**
 422          * Returns true if this database uses timestamps rather than integers
 423          *
 424          * @return bool
 425         */
 426         function realTimestamps() {
 427                 return false;
 428         }
 429
 430         /**
 431          * Returns true if this database does an implicit sort when doing GROUP BY
 432          *
 433          * @return bool
 434          */
 435         function implicitGroupby() {
 436                 return true;
 437         }
 438
 439         /**
 440          * Returns true if this database does an implicit order by when the column has an index
 441          * For example: SELECT page_title FROM page LIMIT 1
 442          *
 443          * @return bool
 444          */
 445         function implicitOrderby() {
 446                 return true;
 447         }
 448
 449         /**
 450          * Returns true if this database requires that SELECT DISTINCT queries require that all
 451            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 452          *
 453          * @return bool
 454          */
 455         function standardSelectDistinct() {
 456                 return true;
 457         }
 458
 459         /**
 460          * Returns true if this database can do a native search on IP columns
 461          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 462          *
 463          * @return bool
 464          */
 465         function searchableIPs() {
 466                 return false;
 467         }
 468
 469         /**
 470          * Returns true if this database can use functional indexes
 471          *
 472          * @return bool
 473          */
 474         function functionalIndexes() {
 475                 return false;
 476         }
 477
 478         /**
 479          * Return the last query that went through DatabaseBase::query()
 480          * @return String
 481          */
 482         function lastQuery() {
 483                 return $this->mLastQuery;
 484         }
 485
 486         /**
 487          * Returns true if the connection may have been used for write queries.
 488          * Should return true if unsure.
 489          *
 490          * @return bool
 491          */
 492         function doneWrites() {
 493                 return $this->mDoneWrites;
 494         }
 495
 496         /**
 497          * Is a connection to the database open?
 498          * @return Boolean
 499          */
 500         function isOpen() {
 501                 return $this->mOpened;
 502         }
 503
 504         /**
 505          * Set a flag for this connection
 506          *
 507          * @param $flag Integer: DBO_* constants from Defines.php:
 508          *   - DBO_DEBUG: output some debug info (same as debug())
 509          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 510          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 511          *   - DBO_TRX: automatically start transactions
 512          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 513          *       and removes it in command line mode
 514          *   - DBO_PERSISTENT: use persistant database connection
 515          */
 516         function setFlag( $flag ) {
 517                 $this->mFlags |= $flag;
 518         }
 519
 520         /**
 521          * Clear a flag for this connection
 522          *
 523          * @param $flag: same as setFlag()'s $flag param
 524          */
 525         function clearFlag( $flag ) {
 526                 $this->mFlags &= ~$flag;
 527         }
 528
 529         /**
 530          * Returns a boolean whether the flag $flag is set for this connection
 531          *
 532          * @param $flag: same as setFlag()'s $flag param
 533          * @return Boolean
 534          */
 535         function getFlag( $flag ) {
 536                 return !!( $this->mFlags & $flag );
 537         }
 538
 539         /**
 540          * General read-only accessor
 541          *
 542          * @param $name string
 543          *
 544          * @return string
 545          */
 546         function getProperty( $name ) {
 547                 return $this->$name;
 548         }
 549
 550         /**
 551          * @return string
 552          */
 553         function getWikiID() {
 554                 if ( $this->mTablePrefix ) {
 555                         return "{$this->mDBname}-{$this->mTablePrefix}";
 556                 } else {
 557                         return $this->mDBname;
 558                 }
 559         }
 560
 561         /**
 562          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 563          *
 564          * @return string
 565          */
 566         public function getSchemaPath() {
 567                 global $IP;
 568                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 569                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 570                 } else {
 571                         return "$IP/maintenance/tables.sql";
 572                 }
 573         }
 574
 575 # ------------------------------------------------------------------------------
 576 # Other functions
 577 # ------------------------------------------------------------------------------
 578
 579         /**
 580          * Constructor.
 581          * @param $server String: database server host
 582          * @param $user String: database user name
 583          * @param $password String: database user password
 584          * @param $dbName String: database name
 585          * @param $flags
 586          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 587          */
 588         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 589                 $flags = 0, $tablePrefix = 'get from global'
 590         ) {
 591                 global $wgDBprefix, $wgCommandLineMode;
 592
 593                 $this->mFlags = $flags;
 594
 595                 if ( $this->mFlags & DBO_DEFAULT ) {
 596                         if ( $wgCommandLineMode ) {
 597                                 $this->mFlags &= ~DBO_TRX;
 598                         } else {
 599                                 $this->mFlags |= DBO_TRX;
 600                         }
 601                 }
 602
 603                 /** Get the default table prefix*/
 604                 if ( $tablePrefix == 'get from global' ) {
 605                         $this->mTablePrefix = $wgDBprefix;
 606                 } else {
 607                         $this->mTablePrefix = $tablePrefix;
 608                 }
 609
 610                 if ( $user ) {
 611                         $this->open( $server, $user, $password, $dbName );
 612                 }
 613         }
 614
 615         /**
 616          * Called by serialize. Throw an exception when DB connection is serialized.
 617          * This causes problems on some database engines because the connection is
 618          * not restored on unserialize.
 619          */
 620         public function __sleep() {
 621                 throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
 622         }
 623
 624         /**
 625          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 626          * @deprecated since 1.17
 627          *
 628          * @param $server
 629          * @param $user
 630          * @param $password
 631          * @param $dbName
 632          * @param $flags int
 633          * @return DatabaseMysql
 634          */
 635         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 636                 wfDeprecated( __METHOD__, '1.17' );
 637                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 638         }
 639
 640         /**
 641          * Same as new factory( ... ), kept for backward compatibility
 642          * @deprecated since 1.18
 643          * @see Database::factory()
 644          */
 645         public final static function newFromType( $dbType, $p = array() ) {
 646                 wfDeprecated( __METHOD__, '1.18' );
 647                 if ( isset( $p['tableprefix'] ) ) {
 648                         $p['tablePrefix'] = $p['tableprefix'];
 649                 }
 650                 return self::factory( $dbType, $p );
 651         }
 652
 653         /**
 654          * Given a DB type, construct the name of the appropriate child class of
 655          * DatabaseBase. This is designed to replace all of the manual stuff like:
 656          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 657          * as well as validate against the canonical list of DB types we have
 658          *
 659          * This factory function is mostly useful for when you need to connect to a
 660          * database other than the MediaWiki default (such as for external auth,
 661          * an extension, et cetera). Do not use this to connect to the MediaWiki
 662          * database. Example uses in core:
 663          * @see LoadBalancer::reallyOpenConnection()
 664          * @see ExternalUser_MediaWiki::initFromCond()
 665          * @see ForeignDBRepo::getMasterDB()
 666          * @see WebInstaller_DBConnect::execute()
 667          *
 668          * @param $dbType String A possible DB type
 669          * @param $p Array An array of options to pass to the constructor.
 670          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 671          * @return DatabaseBase subclass or null
 672          */
 673         public final static function factory( $dbType, $p = array() ) {
 674                 $canonicalDBTypes = array(
 675                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
 676                 );
 677                 $dbType = strtolower( $dbType );
 678
 679                 if( in_array( $dbType, $canonicalDBTypes ) ) {
 680                         $class = 'Database' . ucfirst( $dbType );
 681                         return new $class(
 682                                 isset( $p['host'] ) ? $p['host'] : false,
 683                                 isset( $p['user'] ) ? $p['user'] : false,
 684                                 isset( $p['password'] ) ? $p['password'] : false,
 685                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 686                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 687                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 688                         );
 689                 } else {
 690                         return null;
 691                 }
 692         }
 693
 694         protected function installErrorHandler() {
 695                 $this->mPHPError = false;
 696                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 697                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 698         }
 699
 700         /**
 701          * @return bool|string
 702          */
 703         protected function restoreErrorHandler() {
 704                 restore_error_handler();
 705                 if ( $this->htmlErrors !== false ) {
 706                         ini_set( 'html_errors', $this->htmlErrors );
 707                 }
 708                 if ( $this->mPHPError ) {
 709                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 710                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 711                         return $error;
 712                 } else {
 713                         return false;
 714                 }
 715         }
 716
 717         /**
 718          * @param $errno
 719          * @param $errstr
 720          */
 721         protected function connectionErrorHandler( $errno,  $errstr ) {
 722                 $this->mPHPError = $errstr;
 723         }
 724
 725         /**
 726          * Closes a database connection.
 727          * if it is open : commits any open transactions
 728          *
 729          * @return Bool operation success. true if already closed.
 730          */
 731         function close() {
 732                 # Stub, should probably be overridden
 733                 return true;
 734         }
 735
 736         /**
 737          * @param $error String: fallback error message, used if none is given by DB
 738          */
 739         function reportConnectionError( $error = 'Unknown error' ) {
 740                 $myError = $this->lastError();
 741                 if ( $myError ) {
 742                         $error = $myError;
 743                 }
 744
 745                 # New method
 746                 throw new DBConnectionError( $this, $error );
 747         }
 748
 749         /**
 750          * The DBMS-dependent part of query()
 751          *
 752          * @param  $sql String: SQL query.
 753          * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
 754          */
 755         protected abstract function doQuery( $sql );
 756
 757         /**
 758          * Determine whether a query writes to the DB.
 759          * Should return true if unsure.
 760          *
 761          * @param $sql string
 762          *
 763          * @return bool
 764          */
 765         function isWriteQuery( $sql ) {
 766                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 767         }
 768
 769         /**
 770          * Run an SQL query and return the result. Normally throws a DBQueryError
 771          * on failure. If errors are ignored, returns false instead.
 772          *
 773          * In new code, the query wrappers select(), insert(), update(), delete(),
 774          * etc. should be used where possible, since they give much better DBMS
 775          * independence and automatically quote or validate user input in a variety
 776          * of contexts. This function is generally only useful for queries which are
 777          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 778          * as CREATE TABLE.
 779          *
 780          * However, the query wrappers themselves should call this function.
 781          *
 782          * @param  $sql        String: SQL query
 783          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 784          *     comment (you can use __METHOD__ or add some extra info)
 785          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 786          *     maybe best to catch the exception instead?
 787          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 788          *     for a successful read query, or false on failure if $tempIgnore set
 789          * @throws DBQueryError Thrown when the database returns an error of any kind
 790          */
 791         public function query( $sql, $fname = '', $tempIgnore = false ) {
 792                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 793                 if ( !Profiler::instance()->isStub() ) {
 794                         # generalizeSQL will probably cut down the query to reasonable
 795                         # logging size most of the time. The substr is really just a sanity check.
 796
 797                         if ( $isMaster ) {
 798                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 799                                 $totalProf = 'DatabaseBase::query-master';
 800                         } else {
 801                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 802                                 $totalProf = 'DatabaseBase::query';
 803                         }
 804
 805                         wfProfileIn( $totalProf );
 806                         wfProfileIn( $queryProf );
 807                 }
 808
 809                 $this->mLastQuery = $sql;
 810                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 811                         # Set a flag indicating that writes have been done
 812                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 813                         $this->mDoneWrites = true;
 814                 }
 815
 816                 # Add a comment for easy SHOW PROCESSLIST interpretation
 817                 global $wgUser;
 818                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 819                         $userName = $wgUser->getName();
 820                         if ( mb_strlen( $userName ) > 15 ) {
 821                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 822                         }
 823                         $userName = str_replace( '/', '', $userName );
 824                 } else {
 825                         $userName = '';
 826                 }
 827                 $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 828
 829                 # If DBO_TRX is set, start a transaction
 830                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 831                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 832                         # avoid establishing transactions for SHOW and SET statements too -
 833                         # that would delay transaction initializations to once connection
 834                         # is really used by application
 835                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 836                         if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 )
 837                                 $this->begin();
 838                 }
 839
 840                 if ( $this->debug() ) {
 841                         static $cnt = 0;
 842
 843                         $cnt++;
 844                         $sqlx = substr( $commentedSql, 0, 500 );
 845                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 846
 847                         if ( $isMaster ) {
 848                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 849                         } else {
 850                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 851                         }
 852                 }
 853
 854                 if ( istainted( $sql ) & TC_MYSQL ) {
 855                         throw new MWException( 'Tainted query found' );
 856                 }
 857
 858                 $queryId = MWDebug::query( $sql, $fname, $isMaster );
 859
 860                 # Do the query and handle errors
 861                 $ret = $this->doQuery( $commentedSql );
 862
 863                 MWDebug::queryTime( $queryId );
 864
 865                 # Try reconnecting if the connection was lost
 866                 if ( false === $ret && $this->wasErrorReissuable() ) {
 867                         # Transaction is gone, like it or not
 868                         $this->mTrxLevel = 0;
 869                         wfDebug( "Connection lost, reconnecting...\n" );
 870
 871                         if ( $this->ping() ) {
 872                                 wfDebug( "Reconnected\n" );
 873                                 $sqlx = substr( $commentedSql, 0, 500 );
 874                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 875                                 global $wgRequestTime;
 876                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 877                                 if ( $elapsed < 300 ) {
 878                                         # Not a database error to lose a transaction after a minute or two
 879                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 880                                 }
 881                                 $ret = $this->doQuery( $commentedSql );
 882                         } else {
 883                                 wfDebug( "Failed\n" );
 884                         }
 885                 }
 886
 887                 if ( false === $ret ) {
 888                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 889                 }
 890
 891                 if ( !Profiler::instance()->isStub() ) {
 892                         wfProfileOut( $queryProf );
 893                         wfProfileOut( $totalProf );
 894                 }
 895
 896                 return $this->resultObject( $ret );
 897         }
 898
 899         /**
 900          * Report a query error. Log the error, and if neither the object ignore
 901          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 902          *
 903          * @param $error String
 904          * @param $errno Integer
 905          * @param $sql String
 906          * @param $fname String
 907          * @param $tempIgnore Boolean
 908          */
 909         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 910                 # Ignore errors during error handling to avoid infinite recursion
 911                 $ignore = $this->ignoreErrors( true );
 912                 ++$this->mErrorCount;
 913
 914                 if ( $ignore || $tempIgnore ) {
 915                         wfDebug( "SQL ERROR (ignored): $error\n" );
 916                         $this->ignoreErrors( $ignore );
 917                 } else {
 918                         $sql1line = str_replace( "\n", "\\n", $sql );
 919                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 920                         wfDebug( "SQL ERROR: " . $error . "\n" );
 921                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 922                 }
 923         }
 924
 925         /**
 926          * Intended to be compatible with the PEAR::DB wrapper functions.
 927          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 928          *
 929          * ? = scalar value, quoted as necessary
 930          * ! = raw SQL bit (a function for instance)
 931          * & = filename; reads the file and inserts as a blob
 932          *     (we don't use this though...)
 933          *
 934          * This function should not be used directly by new code outside of the
 935          * database classes. The query wrapper functions (select() etc.) should be
 936          * used instead.
 937          *
 938          * @param $sql string
 939          * @param $func string
 940          *
 941          * @return array
 942          */
 943         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 944                 /* MySQL doesn't support prepared statements (yet), so just
 945                    pack up the query for reference. We'll manually replace
 946                    the bits later. */
 947                 return array( 'query' => $sql, 'func' => $func );
 948         }
 949
 950         /**
 951          * Free a prepared query, generated by prepare().
 952          * @param $prepared
 953          */
 954         function freePrepared( $prepared ) {
 955                 /* No-op by default */
 956         }
 957
 958         /**
 959          * Execute a prepared query with the various arguments
 960          * @param $prepared String: the prepared sql
 961          * @param $args Mixed: Either an array here, or put scalars as varargs
 962          *
 963          * @return ResultWrapper
 964          */
 965         function execute( $prepared, $args = null ) {
 966                 if ( !is_array( $args ) ) {
 967                         # Pull the var args
 968                         $args = func_get_args();
 969                         array_shift( $args );
 970                 }
 971
 972                 $sql = $this->fillPrepared( $prepared['query'], $args );
 973
 974                 return $this->query( $sql, $prepared['func'] );
 975         }
 976
 977         /**
 978          * Prepare & execute an SQL statement, quoting and inserting arguments
 979          * in the appropriate places.
 980          *
 981          * This function should not be used directly by new code outside of the
 982          * database classes. The query wrapper functions (select() etc.) should be
 983          * used instead.
 984          *
 985          * @param $query String
 986          * @param $args ...
 987          *
 988          * @return ResultWrapper
 989          */
 990         function safeQuery( $query, $args = null ) {
 991                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 992
 993                 if ( !is_array( $args ) ) {
 994                         # Pull the var args
 995                         $args = func_get_args();
 996                         array_shift( $args );
 997                 }
 998
 999                 $retval = $this->execute( $prepared, $args );
1000                 $this->freePrepared( $prepared );
1001
1002                 return $retval;
1003         }
1004
1005         /**
1006          * For faking prepared SQL statements on DBs that don't support
1007          * it directly.
1008          * @param $preparedQuery String: a 'preparable' SQL statement
1009          * @param $args Array of arguments to fill it with
1010          * @return string executable SQL
1011          */
1012         function fillPrepared( $preparedQuery, $args ) {
1013                 reset( $args );
1014                 $this->preparedArgs =& $args;
1015
1016                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
1017                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
1018         }
1019
1020         /**
1021          * preg_callback func for fillPrepared()
1022          * The arguments should be in $this->preparedArgs and must not be touched
1023          * while we're doing this.
1024          *
1025          * @param $matches Array
1026          * @return String
1027          */
1028         function fillPreparedArg( $matches ) {
1029                 switch( $matches[1] ) {
1030                         case '\\?': return '?';
1031                         case '\\!': return '!';
1032                         case '\\&': return '&';
1033                 }
1034
1035                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
1036
1037                 switch( $matches[1] ) {
1038                         case '?': return $this->addQuotes( $arg );
1039                         case '!': return $arg;
1040                         case '&':
1041                                 # return $this->addQuotes( file_get_contents( $arg ) );
1042                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
1043                         default:
1044                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
1045                 }
1046         }
1047
1048         /**
1049          * Free a result object returned by query() or select(). It's usually not
1050          * necessary to call this, just use unset() or let the variable holding
1051          * the result object go out of scope.
1052          *
1053          * @param $res Mixed: A SQL result
1054          */
1055         function freeResult( $res ) {
1056         }
1057
1058         /**
1059          * Simple UPDATE wrapper.
1060          * Usually throws a DBQueryError on failure.
1061          * If errors are explicitly ignored, returns success
1062          *
1063          * This function exists for historical reasons, DatabaseBase::update() has a more standard
1064          * calling convention and feature set
1065          *
1066          * @param $table string
1067          * @param $var
1068          * @param $value
1069          * @param $cond
1070          * @param $fname string
1071          *
1072          * @return bool
1073          */
1074         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
1075                 $table = $this->tableName( $table );
1076                 $sql = "UPDATE $table SET $var = '" .
1077                   $this->strencode( $value ) . "' WHERE ($cond)";
1078
1079                 return (bool)$this->query( $sql, $fname );
1080         }
1081
1082         /**
1083          * A SELECT wrapper which returns a single field from a single result row.
1084          *
1085          * Usually throws a DBQueryError on failure. If errors are explicitly
1086          * ignored, returns false on failure.
1087          *
1088          * If no result rows are returned from the query, false is returned.
1089          *
1090          * @param $table string|array Table name. See DatabaseBase::select() for details.
1091          * @param $var string The field name to select. This must be a valid SQL
1092          *   fragment: do not use unvalidated user input.
1093          * @param $cond string|array The condition array. See DatabaseBase::select() for details.
1094          * @param $fname string The function name of the caller.
1095          * @param $options string|array The query options. See DatabaseBase::select() for details.
1096          *
1097          * @return false|mixed The value from the field, or false on failure.
1098          */
1099         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
1100                 $options = array() )
1101         {
1102                 if ( !is_array( $options ) ) {
1103                         $options = array( $options );
1104                 }
1105
1106                 $options['LIMIT'] = 1;
1107
1108                 $res = $this->select( $table, $var, $cond, $fname, $options );
1109
1110                 if ( $res === false || !$this->numRows( $res ) ) {
1111                         return false;
1112                 }
1113
1114                 $row = $this->fetchRow( $res );
1115
1116                 if ( $row !== false ) {
1117                         return reset( $row );
1118                 } else {
1119                         return false;
1120                 }
1121         }
1122
1123         /**
1124          * Returns an optional USE INDEX clause to go after the table, and a
1125          * string to go at the end of the query.
1126          *
1127          * @param $options Array: associative array of options to be turned into
1128          *              an SQL query, valid keys are listed in the function.
1129          * @return Array
1130          * @see DatabaseBase::select()
1131          */
1132         function makeSelectOptions( $options ) {
1133                 $preLimitTail = $postLimitTail = '';
1134                 $startOpts = '';
1135
1136                 $noKeyOptions = array();
1137
1138                 foreach ( $options as $key => $option ) {
1139                         if ( is_numeric( $key ) ) {
1140                                 $noKeyOptions[$option] = true;
1141                         }
1142                 }
1143
1144                 if ( isset( $options['GROUP BY'] ) ) {
1145                         $gb = is_array( $options['GROUP BY'] )
1146                                 ? implode( ',', $options['GROUP BY'] )
1147                                 : $options['GROUP BY'];
1148                         $preLimitTail .= " GROUP BY {$gb}";
1149                 }
1150
1151                 if ( isset( $options['HAVING'] ) ) {
1152                         $preLimitTail .= " HAVING {$options['HAVING']}";
1153                 }
1154
1155                 if ( isset( $options['ORDER BY'] ) ) {
1156                         $ob = is_array( $options['ORDER BY'] )
1157                                 ? implode( ',', $options['ORDER BY'] )
1158                                 : $options['ORDER BY'];
1159                         $preLimitTail .= " ORDER BY {$ob}";
1160                 }
1161
1162                 // if (isset($options['LIMIT'])) {
1163                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1164                 //              isset($options['OFFSET']) ? $options['OFFSET']
1165                 //              : false);
1166                 // }
1167
1168                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1169                         $postLimitTail .= ' FOR UPDATE';
1170                 }
1171
1172                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1173                         $postLimitTail .= ' LOCK IN SHARE MODE';
1174                 }
1175
1176                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1177                         $startOpts .= 'DISTINCT';
1178                 }
1179
1180                 # Various MySQL extensions
1181                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1182                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1183                 }
1184
1185                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1186                         $startOpts .= ' HIGH_PRIORITY';
1187                 }
1188
1189                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1190                         $startOpts .= ' SQL_BIG_RESULT';
1191                 }
1192
1193                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1194                         $startOpts .= ' SQL_BUFFER_RESULT';
1195                 }
1196
1197                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1198                         $startOpts .= ' SQL_SMALL_RESULT';
1199                 }
1200
1201                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1202                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1203                 }
1204
1205                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1206                         $startOpts .= ' SQL_CACHE';
1207                 }
1208
1209                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1210                         $startOpts .= ' SQL_NO_CACHE';
1211                 }
1212
1213                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
1214                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1215                 } else {
1216                         $useIndex = '';
1217                 }
1218
1219                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1220         }
1221
1222         /**
1223          * Execute a SELECT query constructed using the various parameters provided.
1224          * See below for full details of the parameters.
1225          *
1226          * @param $table String|Array Table name
1227          * @param $vars String|Array Field names
1228          * @param $conds String|Array Conditions
1229          * @param $fname String Caller function name
1230          * @param $options Array Query options
1231          * @param $join_conds Array Join conditions
1232          *
1233          * @param $table string|array
1234          *
1235          * May be either an array of table names, or a single string holding a table
1236          * name. If an array is given, table aliases can be specified, for example:
1237          *
1238          *    array( 'a' => 'user' )
1239          *
1240          * This includes the user table in the query, with the alias "a" available
1241          * for use in field names (e.g. a.user_name).
1242          *
1243          * All of the table names given here are automatically run through
1244          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1245          * added, and various other table name mappings to be performed.
1246          *
1247          *
1248          * @param $vars string|array
1249          *
1250          * May be either a field name or an array of field names. The field names
1251          * here are complete fragments of SQL, for direct inclusion into the SELECT
1252          * query. Expressions and aliases may be specified as in SQL, for example:
1253          *
1254          *   array( 'MAX(rev_id) AS maxrev' )
1255          *
1256          * If an expression is given, care must be taken to ensure that it is
1257          * DBMS-independent.
1258          *
1259          *
1260          * @param $conds string|array
1261          *
1262          * May be either a string containing a single condition, or an array of
1263          * conditions. If an array is given, the conditions constructed from each
1264          * element are combined with AND.
1265          *
1266          * Array elements may take one of two forms:
1267          *
1268          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1269          *   - Elements with a string key are interpreted as equality conditions,
1270          *     where the key is the field name.
1271          *     - If the value of such an array element is a scalar (such as a
1272          *       string), it will be treated as data and thus quoted appropriately.
1273          *       If it is null, an IS NULL clause will be added.
1274          *     - If the value is an array, an IN(...) clause will be constructed,
1275          *       such that the field name may match any of the elements in the
1276          *       array. The elements of the array will be quoted.
1277          *
1278          * Note that expressions are often DBMS-dependent in their syntax.
1279          * DBMS-independent wrappers are provided for constructing several types of
1280          * expression commonly used in condition queries. See:
1281          *    - DatabaseBase::buildLike()
1282          *    - DatabaseBase::conditional()
1283          *
1284          *
1285          * @param $options string|array
1286          *
1287          * Optional: Array of query options. Boolean options are specified by
1288          * including them in the array as a string value with a numeric key, for
1289          * example:
1290          *
1291          *    array( 'FOR UPDATE' )
1292          *
1293          * The supported options are:
1294          *
1295          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1296          *     with LIMIT can theoretically be used for paging through a result set,
1297          *     but this is discouraged in MediaWiki for performance reasons.
1298          *
1299          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1300          *     and then the first rows are taken until the limit is reached. LIMIT
1301          *     is applied to a result set after OFFSET.
1302          *
1303          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1304          *     changed until the next COMMIT.
1305          *
1306          *   - DISTINCT: Boolean: return only unique result rows.
1307          *
1308          *   - GROUP BY: May be either an SQL fragment string naming a field or
1309          *     expression to group by, or an array of such SQL fragments.
1310          *
1311          *   - HAVING: A string containing a HAVING clause.
1312          *
1313          *   - ORDER BY: May be either an SQL fragment giving a field name or
1314          *     expression to order by, or an array of such SQL fragments.
1315          *
1316          *   - USE INDEX: This may be either a string giving the index name to use
1317          *     for the query, or an array. If it is an associative array, each key
1318          *     gives the table name (or alias), each value gives the index name to
1319          *     use for that table. All strings are SQL fragments and so should be
1320          *     validated by the caller.
1321          *
1322          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1323          *     instead of SELECT.
1324          *
1325          * And also the following boolean MySQL extensions, see the MySQL manual
1326          * for documentation:
1327          *
1328          *    - LOCK IN SHARE MODE
1329          *    - STRAIGHT_JOIN
1330          *    - HIGH_PRIORITY
1331          *    - SQL_BIG_RESULT
1332          *    - SQL_BUFFER_RESULT
1333          *    - SQL_SMALL_RESULT
1334          *    - SQL_CALC_FOUND_ROWS
1335          *    - SQL_CACHE
1336          *    - SQL_NO_CACHE
1337          *
1338          *
1339          * @param $join_conds string|array
1340          *
1341          * Optional associative array of table-specific join conditions. In the
1342          * most common case, this is unnecessary, since the join condition can be
1343          * in $conds. However, it is useful for doing a LEFT JOIN.
1344          *
1345          * The key of the array contains the table name or alias. The value is an
1346          * array with two elements, numbered 0 and 1. The first gives the type of
1347          * join, the second is an SQL fragment giving the join condition for that
1348          * table. For example:
1349          *
1350          *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1351          *
1352          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1353          *   with no rows in it will be returned. If there was a query error, a
1354          *   DBQueryError exception will be thrown, except if the "ignore errors"
1355          *   option was set, in which case false will be returned.
1356          */
1357         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
1358                 $options = array(), $join_conds = array() ) {
1359                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1360
1361                 return $this->query( $sql, $fname );
1362         }
1363
1364         /**
1365          * The equivalent of DatabaseBase::select() except that the constructed SQL
1366          * is returned, instead of being immediately executed.
1367          *
1368          * @param $table string|array Table name
1369          * @param $vars string|array Field names
1370          * @param $conds string|array Conditions
1371          * @param $fname string Caller function name
1372          * @param $options string|array Query options
1373          * @param $join_conds string|array Join conditions
1374          *
1375          * @return SQL query string.
1376          * @see DatabaseBase::select()
1377          */
1378         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1379                 if ( is_array( $vars ) ) {
1380                         $vars = implode( ',', $vars );
1381                 }
1382
1383                 $options = (array)$options;
1384
1385                 if ( is_array( $table ) ) {
1386                         $useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1387                                 ? $options['USE INDEX']
1388                                 : array();
1389                         if ( count( $join_conds ) || count( $useIndex ) ) {
1390                                 $from = ' FROM ' .
1391                                         $this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
1392                         } else {
1393                                 $from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
1394                         }
1395                 } elseif ( $table != '' ) {
1396                         if ( $table[0] == ' ' ) {
1397                                 $from = ' FROM ' . $table;
1398                         } else {
1399                                 $from = ' FROM ' . $this->tableName( $table );
1400                         }
1401                 } else {
1402                         $from = '';
1403                 }
1404
1405                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1406
1407                 if ( !empty( $conds ) ) {
1408                         if ( is_array( $conds ) ) {
1409                                 $conds = $this->makeList( $conds, LIST_AND );
1410                         }
1411                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1412                 } else {
1413                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1414                 }
1415
1416                 if ( isset( $options['LIMIT'] ) ) {
1417                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1418                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1419                 }
1420                 $sql = "$sql $postLimitTail";
1421
1422                 if ( isset( $options['EXPLAIN'] ) ) {
1423                         $sql = 'EXPLAIN ' . $sql;
1424                 }
1425
1426                 return $sql;
1427         }
1428
1429         /**
1430          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1431          * that a single row object is returned. If the query returns no rows,
1432          * false is returned.
1433          *
1434          * @param $table string|array Table name
1435          * @param $vars string|array Field names
1436          * @param $conds|array Conditions
1437          * @param $fname string Caller function name
1438          * @param $options string|array Query options
1439          * @param $join_conds array|string Join conditions
1440          *
1441          * @return ResultWrapper|bool
1442          */
1443         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
1444                 $options = array(), $join_conds = array() )
1445         {
1446                 $options['LIMIT'] = 1;
1447                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1448
1449                 if ( $res === false ) {
1450                         return false;
1451                 }
1452
1453                 if ( !$this->numRows( $res ) ) {
1454                         return false;
1455                 }
1456
1457                 $obj = $this->fetchObject( $res );
1458
1459                 return $obj;
1460         }
1461
1462         /**
1463          * Estimate rows in dataset.
1464          *
1465          * MySQL allows you to estimate the number of rows that would be returned
1466          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1467          * index cardinality statistics, and is notoriously inaccurate, especially
1468          * when large numbers of rows have recently been added or deleted.
1469          *
1470          * For DBMSs that don't support fast result size estimation, this function
1471          * will actually perform the SELECT COUNT(*).
1472          *
1473          * Takes the same arguments as DatabaseBase::select().
1474          *
1475          * @param $table String: table name
1476          * @param Array|string $vars : unused
1477          * @param Array|string $conds : filters on the table
1478          * @param $fname String: function name for profiling
1479          * @param $options Array: options for select
1480          * @return Integer: row count
1481          */
1482         public function estimateRowCount( $table, $vars = '*', $conds = '',
1483                 $fname = 'DatabaseBase::estimateRowCount', $options = array() )
1484         {
1485                 $rows = 0;
1486                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1487
1488                 if ( $res ) {
1489                         $row = $this->fetchRow( $res );
1490                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1491                 }
1492
1493                 return $rows;
1494         }
1495
1496         /**
1497          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1498          * It's only slightly flawed. Don't use for anything important.
1499          *
1500          * @param $sql String A SQL Query
1501          *
1502          * @return string
1503          */
1504         static function generalizeSQL( $sql ) {
1505                 # This does the same as the regexp below would do, but in such a way
1506                 # as to avoid crashing php on some large strings.
1507                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1508
1509                 $sql = str_replace ( "\\\\", '', $sql );
1510                 $sql = str_replace ( "\\'", '', $sql );
1511                 $sql = str_replace ( "\\\"", '', $sql );
1512                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1513                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1514
1515                 # All newlines, tabs, etc replaced by single space
1516                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1517
1518                 # All numbers => N
1519                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1520
1521                 return $sql;
1522         }
1523
1524         /**
1525          * Determines whether a field exists in a table
1526          *
1527          * @param $table String: table name
1528          * @param $field String: filed to check on that table
1529          * @param $fname String: calling function name (optional)
1530          * @return Boolean: whether $table has filed $field
1531          */
1532         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1533                 $info = $this->fieldInfo( $table, $field );
1534
1535                 return (bool)$info;
1536         }
1537
1538         /**
1539          * Determines whether an index exists
1540          * Usually throws a DBQueryError on failure
1541          * If errors are explicitly ignored, returns NULL on failure
1542          *
1543          * @param $table
1544          * @param $index
1545          * @param $fname string
1546          *
1547          * @return bool|null
1548          */
1549         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1550                 $info = $this->indexInfo( $table, $index, $fname );
1551                 if ( is_null( $info ) ) {
1552                         return null;
1553                 } else {
1554                         return $info !== false;
1555                 }
1556         }
1557
1558         /**
1559          * Query whether a given table exists
1560          *
1561          * @param $table string
1562          * @param $fname string
1563          *
1564          * @return bool
1565          */
1566         function tableExists( $table, $fname = __METHOD__ ) {
1567                 $table = $this->tableName( $table );
1568                 $old = $this->ignoreErrors( true );
1569                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
1570                 $this->ignoreErrors( $old );
1571
1572                 return (bool)$res;
1573         }
1574
1575         /**
1576          * mysql_field_type() wrapper
1577          * @param $res
1578          * @param $index
1579          * @return string
1580          */
1581         function fieldType( $res, $index ) {
1582                 if ( $res instanceof ResultWrapper ) {
1583                         $res = $res->result;
1584                 }
1585
1586                 return mysql_field_type( $res, $index );
1587         }
1588
1589         /**
1590          * Determines if a given index is unique
1591          *
1592          * @param $table string
1593          * @param $index string
1594          *
1595          * @return bool
1596          */
1597         function indexUnique( $table, $index ) {
1598                 $indexInfo = $this->indexInfo( $table, $index );
1599
1600                 if ( !$indexInfo ) {
1601                         return null;
1602                 }
1603
1604                 return !$indexInfo[0]->Non_unique;
1605         }
1606
1607         /**
1608          * Helper for DatabaseBase::insert().
1609          *
1610          * @param $options array
1611          * @return string
1612          */
1613         function makeInsertOptions( $options ) {
1614                 return implode( ' ', $options );
1615         }
1616
1617         /**
1618          * INSERT wrapper, inserts an array into a table.
1619          *
1620          * $a may be either:
1621          *
1622          *   - A single associative array. The array keys are the field names, and
1623          *     the values are the values to insert. The values are treated as data
1624          *     and will be quoted appropriately. If NULL is inserted, this will be
1625          *     converted to a database NULL.
1626          *   - An array with numeric keys, holding a list of associative arrays.
1627          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1628          *     each subarray must be identical to each other, and in the same order.
1629          *
1630          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1631          * returns success.
1632          *
1633          * $options is an array of options, with boolean options encoded as values
1634          * with numeric keys, in the same style as $options in
1635          * DatabaseBase::select(). Supported options are:
1636          *
1637          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1638          *     any rows which cause duplicate key errors are not inserted. It's
1639          *     possible to determine how many rows were successfully inserted using
1640          *     DatabaseBase::affectedRows().
1641          *
1642          * @param $table   String Table name. This will be passed through
1643          *                 DatabaseBase::tableName().
1644          * @param $a       Array of rows to insert
1645          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1646          * @param $options Array of options
1647          *
1648          * @return bool
1649          */
1650         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1651                 # No rows to insert, easy just return now
1652                 if ( !count( $a ) ) {
1653                         return true;
1654                 }
1655
1656                 $table = $this->tableName( $table );
1657
1658                 if ( !is_array( $options ) ) {
1659                         $options = array( $options );
1660                 }
1661
1662                 $options = $this->makeInsertOptions( $options );
1663
1664                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1665                         $multi = true;
1666                         $keys = array_keys( $a[0] );
1667                 } else {
1668                         $multi = false;
1669                         $keys = array_keys( $a );
1670                 }
1671
1672                 $sql = 'INSERT ' . $options .
1673                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1674
1675                 if ( $multi ) {
1676                         $first = true;
1677                         foreach ( $a as $row ) {
1678                                 if ( $first ) {
1679                                         $first = false;
1680                                 } else {
1681                                         $sql .= ',';
1682                                 }
1683                                 $sql .= '(' . $this->makeList( $row ) . ')';
1684                         }
1685                 } else {
1686                         $sql .= '(' . $this->makeList( $a ) . ')';
1687                 }
1688
1689                 return (bool)$this->query( $sql, $fname );
1690         }
1691
1692         /**
1693          * Make UPDATE options for the DatabaseBase::update function
1694          *
1695          * @param $options Array: The options passed to DatabaseBase::update
1696          * @return string
1697          */
1698         function makeUpdateOptions( $options ) {
1699                 if ( !is_array( $options ) ) {
1700                         $options = array( $options );
1701                 }
1702
1703                 $opts = array();
1704
1705                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1706                         $opts[] = $this->lowPriorityOption();
1707                 }
1708
1709                 if ( in_array( 'IGNORE', $options ) ) {
1710                         $opts[] = 'IGNORE';
1711                 }
1712
1713                 return implode( ' ', $opts );
1714         }
1715
1716         /**
1717          * UPDATE wrapper. Takes a condition array and a SET array.
1718          *
1719          * @param $table  String name of the table to UPDATE. This will be passed through
1720          *                DatabaseBase::tableName().
1721          *
1722          * @param $values Array:  An array of values to SET. For each array element,
1723          *                the key gives the field name, and the value gives the data
1724          *                to set that field to. The data will be quoted by
1725          *                DatabaseBase::addQuotes().
1726          *
1727          * @param $conds  Array:  An array of conditions (WHERE). See
1728          *                DatabaseBase::select() for the details of the format of
1729          *                condition arrays. Use '*' to update all rows.
1730          *
1731          * @param $fname  String: The function name of the caller (from __METHOD__),
1732          *                for logging and profiling.
1733          *
1734          * @param $options Array: An array of UPDATE options, can be:
1735          *                   - IGNORE: Ignore unique key conflicts
1736          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1737          * @return Boolean
1738          */
1739         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1740                 $table = $this->tableName( $table );
1741                 $opts = $this->makeUpdateOptions( $options );
1742                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1743
1744                 if ( $conds !== array() && $conds !== '*' ) {
1745                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1746                 }
1747
1748                 return $this->query( $sql, $fname );
1749         }
1750
1751         /**
1752          * Makes an encoded list of strings from an array
1753          * @param $a Array containing the data
1754          * @param $mode int Constant
1755          *      - LIST_COMMA:          comma separated, no field names
1756          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1757          *        the documentation for $conds in DatabaseBase::select().
1758          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1759          *      - LIST_SET:            comma separated with field names, like a SET clause
1760          *      - LIST_NAMES:          comma separated field names
1761          *
1762          * @return string
1763          */
1764         function makeList( $a, $mode = LIST_COMMA ) {
1765                 if ( !is_array( $a ) ) {
1766                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1767                 }
1768
1769                 $first = true;
1770                 $list = '';
1771
1772                 foreach ( $a as $field => $value ) {
1773                         if ( !$first ) {
1774                                 if ( $mode == LIST_AND ) {
1775                                         $list .= ' AND ';
1776                                 } elseif ( $mode == LIST_OR ) {
1777                                         $list .= ' OR ';
1778                                 } else {
1779                                         $list .= ',';
1780                                 }
1781                         } else {
1782                                 $first = false;
1783                         }
1784
1785                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1786                                 $list .= "($value)";
1787                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1788                                 $list .= "$value";
1789                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1790                                 if ( count( $value ) == 0 ) {
1791                                         throw new MWException( __METHOD__ . ': empty input' );
1792                                 } elseif ( count( $value ) == 1 ) {
1793                                         // Special-case single values, as IN isn't terribly efficient
1794                                         // Don't necessarily assume the single key is 0; we don't
1795                                         // enforce linear numeric ordering on other arrays here.
1796                                         $value = array_values( $value );
1797                                         $list .= $field . " = " . $this->addQuotes( $value[0] );
1798                                 } else {
1799                                         $list .= $field . " IN (" . $this->makeList( $value ) . ") ";
1800                                 }
1801                         } elseif ( $value === null ) {
1802                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1803                                         $list .= "$field IS ";
1804                                 } elseif ( $mode == LIST_SET ) {
1805                                         $list .= "$field = ";
1806                                 }
1807                                 $list .= 'NULL';
1808                         } else {
1809                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1810                                         $list .= "$field = ";
1811                                 }
1812                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1813                         }
1814                 }
1815
1816                 return $list;
1817         }
1818
1819         /**
1820          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1821          * The keys on each level may be either integers or strings.
1822          *
1823          * @param $data Array: organized as 2-d
1824          *              array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1825          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1826          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1827          * @return Mixed: string SQL fragment, or false if no items in array.
1828          */
1829         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1830                 $conds = array();
1831
1832                 foreach ( $data as $base => $sub ) {
1833                         if ( count( $sub ) ) {
1834                                 $conds[] = $this->makeList(
1835                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1836                                         LIST_AND );
1837                         }
1838                 }
1839
1840                 if ( $conds ) {
1841                         return $this->makeList( $conds, LIST_OR );
1842                 } else {
1843                         // Nothing to search for...
1844                         return false;
1845                 }
1846         }
1847
1848         /**
1849          * Bitwise operations
1850          */
1851
1852         /**
1853          * @param $field
1854          * @return string
1855          */
1856         function bitNot( $field ) {
1857                 return "(~$field)";
1858         }
1859
1860         /**
1861          * @param $fieldLeft
1862          * @param $fieldRight
1863          * @return string
1864          */
1865         function bitAnd( $fieldLeft, $fieldRight ) {
1866                 return "($fieldLeft & $fieldRight)";
1867         }
1868
1869         /**
1870          * @param  $fieldLeft
1871          * @param  $fieldRight
1872          * @return string
1873          */
1874         function bitOr( $fieldLeft, $fieldRight ) {
1875                 return "($fieldLeft | $fieldRight)";
1876         }
1877
1878         /**
1879          * Change the current database
1880          *
1881          * @todo Explain what exactly will fail if this is not overridden.
1882          *
1883          * @param $db
1884          *
1885          * @return bool Success or failure
1886          */
1887         function selectDB( $db ) {
1888                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1889                 # if your database engine supports a concept similar to MySQL's
1890                 # databases you may as well.
1891                 $this->mDBname = $db;
1892                 return true;
1893         }
1894
1895         /**
1896          * Get the current DB name
1897          */
1898         function getDBname() {
1899                 return $this->mDBname;
1900         }
1901
1902         /**
1903          * Get the server hostname or IP address
1904          */
1905         function getServer() {
1906                 return $this->mServer;
1907         }
1908
1909         /**
1910          * Format a table name ready for use in constructing an SQL query
1911          *
1912          * This does two important things: it quotes the table names to clean them up,
1913          * and it adds a table prefix if only given a table name with no quotes.
1914          *
1915          * All functions of this object which require a table name call this function
1916          * themselves. Pass the canonical name to such functions. This is only needed
1917          * when calling query() directly.
1918          *
1919          * @param $name String: database table name
1920          * @param $format String One of:
1921          *   quoted - Automatically pass the table name through addIdentifierQuotes()
1922          *            so that it can be used in a query.
1923          *   raw - Do not add identifier quotes to the table name
1924          * @return String: full database name
1925          */
1926         function tableName( $name, $format = 'quoted' ) {
1927                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1928                 # Skip the entire process when we have a string quoted on both ends.
1929                 # Note that we check the end so that we will still quote any use of
1930                 # use of `database`.table. But won't break things if someone wants
1931                 # to query a database table with a dot in the name.
1932                 if ( $this->isQuotedIdentifier( $name ) ) {
1933                         return $name;
1934                 }
1935
1936                 # Lets test for any bits of text that should never show up in a table
1937                 # name. Basically anything like JOIN or ON which are actually part of
1938                 # SQL queries, but may end up inside of the table value to combine
1939                 # sql. Such as how the API is doing.
1940                 # Note that we use a whitespace test rather than a \b test to avoid
1941                 # any remote case where a word like on may be inside of a table name
1942                 # surrounded by symbols which may be considered word breaks.
1943                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1944                         return $name;
1945                 }
1946
1947                 # Split database and table into proper variables.
1948                 # We reverse the explode so that database.table and table both output
1949                 # the correct table.
1950                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1951                 if ( isset( $dbDetails[1] ) ) {
1952                         list( $table, $database ) = $dbDetails;
1953                 } else {
1954                         list( $table ) = $dbDetails;
1955                 }
1956                 $prefix = $this->mTablePrefix; # Default prefix
1957
1958                 # A database name has been specified in input. We don't want any
1959                 # prefixes added.
1960                 if ( isset( $database ) ) {
1961                         $prefix = '';
1962                 }
1963
1964                 # Note that we use the long format because php will complain in in_array if
1965                 # the input is not an array, and will complain in is_array if it is not set.
1966                 if ( !isset( $database ) # Don't use shared database if pre selected.
1967                  && isset( $wgSharedDB ) # We have a shared database
1968                  && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
1969                  && isset( $wgSharedTables )
1970                  && is_array( $wgSharedTables )
1971                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1972                         $database = $wgSharedDB;
1973                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1974                 }
1975
1976                 # Quote the $database and $table and apply the prefix if not quoted.
1977                 if ( isset( $database ) ) {
1978                         $database = ( $format == 'quoted' || $this->isQuotedIdentifier( $database ) ? $database : $this->addIdentifierQuotes( $database ) );
1979                 }
1980
1981                 $table = "{$prefix}{$table}";
1982                 if ( $format == 'quoted' && !$this->isQuotedIdentifier( $table ) ) {
1983                         $table = $this->addIdentifierQuotes( "{$table}" );
1984                 }
1985
1986                 # Merge our database and table into our final table name.
1987                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1988
1989                 return $tableName;
1990         }
1991
1992         /**
1993          * Fetch a number of table names into an array
1994          * This is handy when you need to construct SQL for joins
1995          *
1996          * Example:
1997          * extract($dbr->tableNames('user','watchlist'));
1998          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
1999          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2000          *
2001          * @return array
2002          */
2003         public function tableNames() {
2004                 $inArray = func_get_args();
2005                 $retVal = array();
2006
2007                 foreach ( $inArray as $name ) {
2008                         $retVal[$name] = $this->tableName( $name );
2009                 }
2010
2011                 return $retVal;
2012         }
2013
2014         /**
2015          * Fetch a number of table names into an zero-indexed numerical array
2016          * This is handy when you need to construct SQL for joins
2017          *
2018          * Example:
2019          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
2020          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2021          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2022          *
2023          * @return array
2024          */
2025         public function tableNamesN() {
2026                 $inArray = func_get_args();
2027                 $retVal = array();
2028
2029                 foreach ( $inArray as $name ) {
2030                         $retVal[] = $this->tableName( $name );
2031                 }
2032
2033                 return $retVal;
2034         }
2035
2036         /**
2037          * Get an aliased table name
2038          * e.g. tableName AS newTableName
2039          *
2040          * @param $name string Table name, see tableName()
2041          * @param $alias string|bool Alias (optional)
2042          * @return string SQL name for aliased table. Will not alias a table to its own name
2043          */
2044         public function tableNameWithAlias( $name, $alias = false ) {
2045                 if ( !$alias || $alias == $name ) {
2046                         return $this->tableName( $name );
2047                 } else {
2048                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2049                 }
2050         }
2051
2052         /**
2053          * Gets an array of aliased table names
2054          *
2055          * @param $tables array( [alias] => table )
2056          * @return array of strings, see tableNameWithAlias()
2057          */
2058         public function tableNamesWithAlias( $tables ) {
2059                 $retval = array();
2060                 foreach ( $tables as $alias => $table ) {
2061                         if ( is_numeric( $alias ) ) {
2062                                 $alias = $table;
2063                         }
2064                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2065                 }
2066                 return $retval;
2067         }
2068
2069         /**
2070          * Get the aliased table name clause for a FROM clause
2071          * which might have a JOIN and/or USE INDEX clause
2072          *
2073          * @param $tables array ( [alias] => table )
2074          * @param $use_index array Same as for select()
2075          * @param $join_conds array Same as for select()
2076          * @return string
2077          */
2078         protected function tableNamesWithUseIndexOrJOIN(
2079                 $tables, $use_index = array(), $join_conds = array()
2080         ) {
2081                 $ret = array();
2082                 $retJOIN = array();
2083                 $use_index = (array)$use_index;
2084                 $join_conds = (array)$join_conds;
2085
2086                 foreach ( $tables as $alias => $table ) {
2087                         if ( !is_string( $alias ) ) {
2088                                 // No alias? Set it equal to the table name
2089                                 $alias = $table;
2090                         }
2091                         // Is there a JOIN clause for this table?
2092                         if ( isset( $join_conds[$alias] ) ) {
2093                                 list( $joinType, $conds ) = $join_conds[$alias];
2094                                 $tableClause = $joinType;
2095                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2096                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2097                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2098                                         if ( $use != '' ) {
2099                                                 $tableClause .= ' ' . $use;
2100                                         }
2101                                 }
2102                                 $on = $this->makeList( (array)$conds, LIST_AND );
2103                                 if ( $on != '' ) {
2104                                         $tableClause .= ' ON (' . $on . ')';
2105                                 }
2106
2107                                 $retJOIN[] = $tableClause;
2108                         // Is there an INDEX clause for this table?
2109                         } elseif ( isset( $use_index[$alias] ) ) {
2110                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2111                                 $tableClause .= ' ' . $this->useIndexClause(
2112                                         implode( ',', (array)$use_index[$alias] ) );
2113
2114                                 $ret[] = $tableClause;
2115                         } else {
2116                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2117
2118                                 $ret[] = $tableClause;
2119                         }
2120                 }
2121
2122                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2123                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2124                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2125
2126                 // Compile our final table clause
2127                 return implode( ' ', array( $straightJoins, $otherJoins ) );
2128         }
2129
2130         /**
2131          * Get the name of an index in a given table
2132          *
2133          * @param $index
2134          *
2135          * @return string
2136          */
2137         function indexName( $index ) {
2138                 // Backwards-compatibility hack
2139                 $renamed = array(
2140                         'ar_usertext_timestamp' => 'usertext_timestamp',
2141                         'un_user_id'            => 'user_id',
2142                         'un_user_ip'            => 'user_ip',
2143                 );
2144
2145                 if ( isset( $renamed[$index] ) ) {
2146                         return $renamed[$index];
2147                 } else {
2148                         return $index;
2149                 }
2150         }
2151
2152         /**
2153          * If it's a string, adds quotes and backslashes
2154          * Otherwise returns as-is
2155          *
2156          * @param $s string
2157          *
2158          * @return string
2159          */
2160         function addQuotes( $s ) {
2161                 if ( $s === null ) {
2162                         return 'NULL';
2163                 } else {
2164                         # This will also quote numeric values. This should be harmless,
2165                         # and protects against weird problems that occur when they really
2166                         # _are_ strings such as article titles and string->number->string
2167                         # conversion is not 1:1.
2168                         return "'" . $this->strencode( $s ) . "'";
2169                 }
2170         }
2171
2172         /**
2173          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2174          * MySQL uses `backticks` while basically everything else uses double quotes.
2175          * Since MySQL is the odd one out here the double quotes are our generic
2176          * and we implement backticks in DatabaseMysql.
2177          *
2178          * @param $s string
2179          *
2180          * @return string
2181          */
2182         public function addIdentifierQuotes( $s ) {
2183                 return '"' . str_replace( '"', '""', $s ) . '"';
2184         }
2185
2186         /**
2187          * Returns if the given identifier looks quoted or not according to
2188          * the database convention for quoting identifiers .
2189          *
2190          * @param $name string
2191          *
2192          * @return boolean
2193          */
2194         public function isQuotedIdentifier( $name ) {
2195                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2196         }
2197
2198         /**
2199          * Backwards compatibility, identifier quoting originated in DatabasePostgres
2200          * which used quote_ident which does not follow our naming conventions
2201          * was renamed to addIdentifierQuotes.
2202          * @deprecated since 1.18 use addIdentifierQuotes
2203          *
2204          * @param $s string
2205          *
2206          * @return string
2207          */
2208         function quote_ident( $s ) {
2209                 wfDeprecated( __METHOD__, '1.18' );
2210                 return $this->addIdentifierQuotes( $s );
2211         }
2212
2213         /**
2214          * Escape string for safe LIKE usage.
2215          * WARNING: you should almost never use this function directly,
2216          * instead use buildLike() that escapes everything automatically
2217          * @deprecated since 1.17, warnings in 1.17, removed in ???
2218          *
2219          * @param $s string
2220          *
2221          * @return string
2222          */
2223         public function escapeLike( $s ) {
2224                 wfDeprecated( __METHOD__, '1.17' );
2225                 return $this->escapeLikeInternal( $s );
2226         }
2227
2228         /**
2229          * @param $s string
2230          * @return string
2231          */
2232         protected function escapeLikeInternal( $s ) {
2233                 $s = str_replace( '\\', '\\\\', $s );
2234                 $s = $this->strencode( $s );
2235                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2236
2237                 return $s;
2238         }
2239
2240         /**
2241          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2242          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2243          * Alternatively, the function could be provided with an array of aforementioned parameters.
2244          *
2245          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2246          * for subpages of 'My page title'.
2247          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2248          *
2249          * @since 1.16
2250          * @return String: fully built LIKE statement
2251          */
2252         function buildLike() {
2253                 $params = func_get_args();
2254
2255                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2256                         $params = $params[0];
2257                 }
2258
2259                 $s = '';
2260
2261                 foreach ( $params as $value ) {
2262                         if ( $value instanceof LikeMatch ) {
2263                                 $s .= $value->toString();
2264                         } else {
2265                                 $s .= $this->escapeLikeInternal( $value );
2266                         }
2267                 }
2268
2269                 return " LIKE '" . $s . "' ";
2270         }
2271
2272         /**
2273          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2274          *
2275          * @return LikeMatch
2276          */
2277         function anyChar() {
2278                 return new LikeMatch( '_' );
2279         }
2280
2281         /**
2282          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2283          *
2284          * @return LikeMatch
2285          */
2286         function anyString() {
2287                 return new LikeMatch( '%' );
2288         }
2289
2290         /**
2291          * Returns an appropriately quoted sequence value for inserting a new row.
2292          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2293          * subclass will return an integer, and save the value for insertId()
2294          *
2295          * Any implementation of this function should *not* involve reusing
2296          * sequence numbers created for rolled-back transactions.
2297          * See http://bugs.mysql.com/bug.php?id=30767 for details.
2298          * @param $seqName string
2299          * @return null
2300          */
2301         function nextSequenceValue( $seqName ) {
2302                 return null;
2303         }
2304
2305         /**
2306          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2307          * is only needed because a) MySQL must be as efficient as possible due to
2308          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2309          * which index to pick.  Anyway, other databases might have different
2310          * indexes on a given table.  So don't bother overriding this unless you're
2311          * MySQL.
2312          * @param $index
2313          * @return string
2314          */
2315         function useIndexClause( $index ) {
2316                 return '';
2317         }
2318
2319         /**
2320          * REPLACE query wrapper.
2321          *
2322          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2323          * except that when there is a duplicate key error, the old row is deleted
2324          * and the new row is inserted in its place.
2325          *
2326          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2327          * perform the delete, we need to know what the unique indexes are so that
2328          * we know how to find the conflicting rows.
2329          *
2330          * It may be more efficient to leave off unique indexes which are unlikely
2331          * to collide. However if you do this, you run the risk of encountering
2332          * errors which wouldn't have occurred in MySQL.
2333          *
2334          * @param $table String: The table to replace the row(s) in.
2335          * @param $rows array Can be either a single row to insert, or multiple rows,
2336          *    in the same format as for DatabaseBase::insert()
2337          * @param $uniqueIndexes array is an array of indexes. Each element may be either
2338          *    a field name or an array of field names
2339          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
2340          */
2341         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
2342                 $quotedTable = $this->tableName( $table );
2343
2344                 if ( count( $rows ) == 0 ) {
2345                         return;
2346                 }
2347
2348                 # Single row case
2349                 if ( !is_array( reset( $rows ) ) ) {
2350                         $rows = array( $rows );
2351                 }
2352
2353                 foreach( $rows as $row ) {
2354                         # Delete rows which collide
2355                         if ( $uniqueIndexes ) {
2356                                 $sql = "DELETE FROM $quotedTable WHERE ";
2357                                 $first = true;
2358                                 foreach ( $uniqueIndexes as $index ) {
2359                                         if ( $first ) {
2360                                                 $first = false;
2361                                                 $sql .= '( ';
2362                                         } else {
2363                                                 $sql .= ' ) OR ( ';
2364                                         }
2365                                         if ( is_array( $index ) ) {
2366                                                 $first2 = true;
2367                                                 foreach ( $index as $col ) {
2368                                                         if ( $first2 ) {
2369                                                                 $first2 = false;
2370                                                         } else {
2371                                                                 $sql .= ' AND ';
2372                                                         }
2373                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2374                                                 }
2375                                         } else {
2376                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2377                                         }
2378                                 }
2379                                 $sql .= ' )';
2380                                 $this->query( $sql, $fname );
2381                         }
2382
2383                         # Now insert the row
2384                         $this->insert( $table, $row );
2385                 }
2386         }
2387
2388         /**
2389          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2390          * statement.
2391          *
2392          * @param $table string Table name
2393          * @param $rows array Rows to insert
2394          * @param $fname string Caller function name
2395          *
2396          * @return ResultWrapper
2397          */
2398         protected function nativeReplace( $table, $rows, $fname ) {
2399                 $table = $this->tableName( $table );
2400
2401                 # Single row case
2402                 if ( !is_array( reset( $rows ) ) ) {
2403                         $rows = array( $rows );
2404                 }
2405
2406                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2407                 $first = true;
2408
2409                 foreach ( $rows as $row ) {
2410                         if ( $first ) {
2411                                 $first = false;
2412                         } else {
2413                                 $sql .= ',';
2414                         }
2415
2416                         $sql .= '(' . $this->makeList( $row ) . ')';
2417                 }
2418
2419                 return $this->query( $sql, $fname );
2420         }
2421
2422         /**
2423          * DELETE where the condition is a join.
2424          *
2425          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2426          * we use sub-selects
2427          *
2428          * For safety, an empty $conds will not delete everything. If you want to
2429          * delete all rows where the join condition matches, set $conds='*'.
2430          *
2431          * DO NOT put the join condition in $conds.
2432          *
2433          * @param $delTable   String: The table to delete from.
2434          * @param $joinTable  String: The other table.
2435          * @param $delVar     String: The variable to join on, in the first table.
2436          * @param $joinVar    String: The variable to join on, in the second table.
2437          * @param $conds      Array: Condition array of field names mapped to variables,
2438          *                    ANDed together in the WHERE clause
2439          * @param $fname      String: Calling function name (use __METHOD__) for
2440          *                    logs/profiling
2441          */
2442         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2443                 $fname = 'DatabaseBase::deleteJoin' )
2444         {
2445                 if ( !$conds ) {
2446                         throw new DBUnexpectedError( $this,
2447                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2448                 }
2449
2450                 $delTable = $this->tableName( $delTable );
2451                 $joinTable = $this->tableName( $joinTable );
2452                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2453                 if ( $conds != '*' ) {
2454                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2455                 }
2456                 $sql .= ')';
2457
2458                 $this->query( $sql, $fname );
2459         }
2460
2461         /**
2462          * Returns the size of a text field, or -1 for "unlimited"
2463          *
2464          * @param $table string
2465          * @param $field string
2466          *
2467          * @return int
2468          */
2469         function textFieldSize( $table, $field ) {
2470                 $table = $this->tableName( $table );
2471                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2472                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2473                 $row = $this->fetchObject( $res );
2474
2475                 $m = array();
2476
2477                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2478                         $size = $m[1];
2479                 } else {
2480                         $size = -1;
2481                 }
2482
2483                 return $size;
2484         }
2485
2486         /**
2487          * A string to insert into queries to show that they're low-priority, like
2488          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2489          * string and nothing bad should happen.
2490          *
2491          * @return string Returns the text of the low priority option if it is
2492          *   supported, or a blank string otherwise
2493          */
2494         function lowPriorityOption() {
2495                 return '';
2496         }
2497
2498         /**
2499          * DELETE query wrapper.
2500          *
2501          * @param $table Array Table name
2502          * @param $conds String|Array of conditions. See $conds in DatabaseBase::select() for
2503          *               the format. Use $conds == "*" to delete all rows
2504          * @param $fname String name of the calling function
2505          *
2506          * @return bool
2507          */
2508         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
2509                 if ( !$conds ) {
2510                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2511                 }
2512
2513                 $table = $this->tableName( $table );
2514                 $sql = "DELETE FROM $table";
2515
2516                 if ( $conds != '*' ) {
2517                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2518                 }
2519
2520                 return $this->query( $sql, $fname );
2521         }
2522
2523         /**
2524          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2525          * into another table.
2526          *
2527          * @param $destTable string The table name to insert into
2528          * @param $srcTable string|array May be either a table name, or an array of table names
2529          *    to include in a join.
2530          *
2531          * @param $varMap array must be an associative array of the form
2532          *    array( 'dest1' => 'source1', ...). Source items may be literals
2533          *    rather than field names, but strings should be quoted with
2534          *    DatabaseBase::addQuotes()
2535          *
2536          * @param $conds array Condition array. See $conds in DatabaseBase::select() for
2537          *    the details of the format of condition arrays. May be "*" to copy the
2538          *    whole table.
2539          *
2540          * @param $fname string The function name of the caller, from __METHOD__
2541          *
2542          * @param $insertOptions array Options for the INSERT part of the query, see
2543          *    DatabaseBase::insert() for details.
2544          * @param $selectOptions array Options for the SELECT part of the query, see
2545          *    DatabaseBase::select() for details.
2546          *
2547          * @return ResultWrapper
2548          */
2549         function insertSelect( $destTable, $srcTable, $varMap, $conds,
2550                 $fname = 'DatabaseBase::insertSelect',
2551                 $insertOptions = array(), $selectOptions = array() )
2552         {
2553                 $destTable = $this->tableName( $destTable );
2554
2555                 if ( is_array( $insertOptions ) ) {
2556                         $insertOptions = implode( ' ', $insertOptions );
2557                 }
2558
2559                 if ( !is_array( $selectOptions ) ) {
2560                         $selectOptions = array( $selectOptions );
2561                 }
2562
2563                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2564
2565                 if ( is_array( $srcTable ) ) {
2566                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2567                 } else {
2568                         $srcTable = $this->tableName( $srcTable );
2569                 }
2570
2571                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2572                         " SELECT $startOpts " . implode( ',', $varMap ) .
2573                         " FROM $srcTable $useIndex ";
2574
2575                 if ( $conds != '*' ) {
2576                         if ( is_array( $conds ) ) {
2577                                 $conds = $this->makeList( $conds, LIST_AND );
2578                         }
2579                         $sql .= " WHERE $conds";
2580                 }
2581
2582                 $sql .= " $tailOpts";
2583
2584                 return $this->query( $sql, $fname );
2585         }
2586
2587         /**
2588          * Construct a LIMIT query with optional offset.  This is used for query
2589          * pages.  The SQL should be adjusted so that only the first $limit rows
2590          * are returned.  If $offset is provided as well, then the first $offset
2591          * rows should be discarded, and the next $limit rows should be returned.
2592          * If the result of the query is not ordered, then the rows to be returned
2593          * are theoretically arbitrary.
2594          *
2595          * $sql is expected to be a SELECT, if that makes a difference.  For
2596          * UPDATE, limitResultForUpdate should be used.
2597          *
2598          * The version provided by default works in MySQL and SQLite.  It will very
2599          * likely need to be overridden for most other DBMSes.
2600          *
2601          * @param $sql String SQL query we will append the limit too
2602          * @param $limit Integer the SQL limit
2603          * @param $offset Integer|false the SQL offset (default false)
2604          *
2605          * @return string
2606          */
2607         function limitResult( $sql, $limit, $offset = false ) {
2608                 if ( !is_numeric( $limit ) ) {
2609                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2610                 }
2611
2612                 return "$sql LIMIT "
2613                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2614                                 . "{$limit} ";
2615         }
2616
2617         /**
2618          * @param $sql
2619          * @param $num
2620          * @return string
2621          */
2622         function limitResultForUpdate( $sql, $num ) {
2623                 return $this->limitResult( $sql, $num, 0 );
2624         }
2625
2626         /**
2627          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2628          * within the UNION construct.
2629          * @return Boolean
2630          */
2631         function unionSupportsOrderAndLimit() {
2632                 return true; // True for almost every DB supported
2633         }
2634
2635         /**
2636          * Construct a UNION query
2637          * This is used for providing overload point for other DB abstractions
2638          * not compatible with the MySQL syntax.
2639          * @param $sqls Array: SQL statements to combine
2640          * @param $all Boolean: use UNION ALL
2641          * @return String: SQL fragment
2642          */
2643         function unionQueries( $sqls, $all ) {
2644                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2645                 return '(' . implode( $glue, $sqls ) . ')';
2646         }
2647
2648         /**
2649          * Returns an SQL expression for a simple conditional.  This doesn't need
2650          * to be overridden unless CASE isn't supported in your DBMS.
2651          *
2652          * @param $cond String: SQL expression which will result in a boolean value
2653          * @param $trueVal String: SQL expression to return if true
2654          * @param $falseVal String: SQL expression to return if false
2655          * @return String: SQL fragment
2656          */
2657         function conditional( $cond, $trueVal, $falseVal ) {
2658                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2659         }
2660
2661         /**
2662          * Returns a comand for str_replace function in SQL query.
2663          * Uses REPLACE() in MySQL
2664          *
2665          * @param $orig String: column to modify
2666          * @param $old String: column to seek
2667          * @param $new String: column to replace with
2668          *
2669          * @return string
2670          */
2671         function strreplace( $orig, $old, $new ) {
2672                 return "REPLACE({$orig}, {$old}, {$new})";
2673         }
2674
2675         /**
2676          * Determines how long the server has been up
2677          * STUB
2678          *
2679          * @return int
2680          */
2681         function getServerUptime() {
2682                 return 0;
2683         }
2684
2685         /**
2686          * Determines if the last failure was due to a deadlock
2687          * STUB
2688          *
2689          * @return bool
2690          */
2691         function wasDeadlock() {
2692                 return false;
2693         }
2694
2695         /**
2696          * Determines if the last failure was due to a lock timeout
2697          * STUB
2698          *
2699          * @return bool
2700          */
2701         function wasLockTimeout() {
2702                 return false;
2703         }
2704
2705         /**
2706          * Determines if the last query error was something that should be dealt
2707          * with by pinging the connection and reissuing the query.
2708          * STUB
2709          *
2710          * @return bool
2711          */
2712         function wasErrorReissuable() {
2713                 return false;
2714         }
2715
2716         /**
2717          * Determines if the last failure was due to the database being read-only.
2718          * STUB
2719          *
2720          * @return bool
2721          */
2722         function wasReadOnlyError() {
2723                 return false;
2724         }
2725
2726         /**
2727          * Perform a deadlock-prone transaction.
2728          *
2729          * This function invokes a callback function to perform a set of write
2730          * queries. If a deadlock occurs during the processing, the transaction
2731          * will be rolled back and the callback function will be called again.
2732          *
2733          * Usage:
2734          *   $dbw->deadlockLoop( callback, ... );
2735          *
2736          * Extra arguments are passed through to the specified callback function.
2737          *
2738          * Returns whatever the callback function returned on its successful,
2739          * iteration, or false on error, for example if the retry limit was
2740          * reached.
2741          *
2742          * @return bool
2743          */
2744         function deadlockLoop() {
2745                 $myFname = 'DatabaseBase::deadlockLoop';
2746
2747                 $this->begin();
2748                 $args = func_get_args();
2749                 $function = array_shift( $args );
2750                 $oldIgnore = $this->ignoreErrors( true );
2751                 $tries = DEADLOCK_TRIES;
2752
2753                 if ( is_array( $function ) ) {
2754                         $fname = $function[0];
2755                 } else {
2756                         $fname = $function;
2757                 }
2758
2759                 do {
2760                         $retVal = call_user_func_array( $function, $args );
2761                         $error = $this->lastError();
2762                         $errno = $this->lastErrno();
2763                         $sql = $this->lastQuery();
2764
2765                         if ( $errno ) {
2766                                 if ( $this->wasDeadlock() ) {
2767                                         # Retry
2768                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2769                                 } else {
2770                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2771                                 }
2772                         }
2773                 } while ( $this->wasDeadlock() && --$tries > 0 );
2774
2775                 $this->ignoreErrors( $oldIgnore );
2776
2777                 if ( $tries <= 0 ) {
2778                         $this->rollback( $myFname );
2779                         $this->reportQueryError( $error, $errno, $sql, $fname );
2780                         return false;
2781                 } else {
2782                         $this->commit( $myFname );
2783                         return $retVal;
2784                 }
2785         }
2786
2787         /**
2788          * Wait for the slave to catch up to a given master position.
2789          *
2790          * @param $pos DBMasterPos object
2791          * @param $timeout Integer: the maximum number of seconds to wait for
2792          *   synchronisation
2793          *
2794          * @return An integer: zero if the slave was past that position already,
2795          *   greater than zero if we waited for some period of time, less than
2796          *   zero if we timed out.
2797          */
2798         function masterPosWait( DBMasterPos $pos, $timeout ) {
2799                 $fname = 'DatabaseBase::masterPosWait';
2800                 wfProfileIn( $fname );
2801
2802                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2803                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2804
2805                         if ( $wait > $timeout * 1e6 ) {
2806                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2807                                 wfProfileOut( $fname );
2808                                 return -1;
2809                         } elseif ( $wait > 0 ) {
2810                                 wfDebug( "Fake slave waiting $wait us\n" );
2811                                 usleep( $wait );
2812                                 wfProfileOut( $fname );
2813                                 return 1;
2814                         } else {
2815                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2816                                 wfProfileOut( $fname );
2817                                 return 0;
2818                         }
2819                 }
2820
2821                 wfProfileOut( $fname );
2822
2823                 # Real waits are implemented in the subclass.
2824                 return 0;
2825         }
2826
2827         /**
2828          * Get the replication position of this slave
2829          *
2830          * @return DBMasterPos, or false if this is not a slave.
2831          */
2832         function getSlavePos() {
2833                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2834                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2835                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2836                         return $pos;
2837                 } else {
2838                         # Stub
2839                         return false;
2840                 }
2841         }
2842
2843         /**
2844          * Get the position of this master
2845          *
2846          * @return DBMasterPos, or false if this is not a master
2847          */
2848         function getMasterPos() {
2849                 if ( $this->mFakeMaster ) {
2850                         return new MySQLMasterPos( 'fake', microtime( true ) );
2851                 } else {
2852                         return false;
2853                 }
2854         }
2855
2856         /**
2857          * Begin a transaction, committing any previously open transaction
2858          *
2859          * @param $fname string
2860          */
2861         function begin( $fname = 'DatabaseBase::begin' ) {
2862                 $this->query( 'BEGIN', $fname );
2863                 $this->mTrxLevel = 1;
2864         }
2865
2866         /**
2867          * End a transaction
2868          *
2869          * @param $fname string
2870          */
2871         function commit( $fname = 'DatabaseBase::commit' ) {
2872                 if ( $this->mTrxLevel ) {
2873                         $this->query( 'COMMIT', $fname );
2874                         $this->mTrxLevel = 0;
2875                 }
2876         }
2877
2878         /**
2879          * Rollback a transaction.
2880          * No-op on non-transactional databases.
2881          *
2882          * @param $fname string
2883          */
2884         function rollback( $fname = 'DatabaseBase::rollback' ) {
2885                 if ( $this->mTrxLevel ) {
2886                         $this->query( 'ROLLBACK', $fname, true );
2887                         $this->mTrxLevel = 0;
2888                 }
2889         }
2890
2891         /**
2892          * Creates a new table with structure copied from existing table
2893          * Note that unlike most database abstraction functions, this function does not
2894          * automatically append database prefix, because it works at a lower
2895          * abstraction level.
2896          * The table names passed to this function shall not be quoted (this
2897          * function calls addIdentifierQuotes when needed).
2898          *
2899          * @param $oldName String: name of table whose structure should be copied
2900          * @param $newName String: name of table to be created
2901          * @param $temporary Boolean: whether the new table should be temporary
2902          * @param $fname String: calling function name
2903          * @return Boolean: true if operation was successful
2904          */
2905         function duplicateTableStructure( $oldName, $newName, $temporary = false,
2906                 $fname = 'DatabaseBase::duplicateTableStructure' )
2907         {
2908                 throw new MWException(
2909                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2910         }
2911
2912         /**
2913          * List all tables on the database
2914          *
2915          * @param $prefix Only show tables with this prefix, e.g. mw_
2916          * @param $fname String: calling function name
2917          */
2918         function listTables( $prefix = null, $fname = 'DatabaseBase::listTables' ) {
2919                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2920         }
2921
2922         /**
2923          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2924          * to the format used for inserting into timestamp fields in this DBMS.
2925          *
2926          * The result is unquoted, and needs to be passed through addQuotes()
2927          * before it can be included in raw SQL.
2928          *
2929          * @param $ts string|int
2930          *
2931          * @return string
2932          */
2933         function timestamp( $ts = 0 ) {
2934                 return wfTimestamp( TS_MW, $ts );
2935         }
2936
2937         /**
2938          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2939          * to the format used for inserting into timestamp fields in this DBMS. If
2940          * NULL is input, it is passed through, allowing NULL values to be inserted
2941          * into timestamp fields.
2942          *
2943          * The result is unquoted, and needs to be passed through addQuotes()
2944          * before it can be included in raw SQL.
2945          *
2946          * @param $ts string|int
2947          *
2948          * @return string
2949          */
2950         function timestampOrNull( $ts = null ) {
2951                 if ( is_null( $ts ) ) {
2952                         return null;
2953                 } else {
2954                         return $this->timestamp( $ts );
2955                 }
2956         }
2957
2958         /**
2959          * Take the result from a query, and wrap it in a ResultWrapper if
2960          * necessary. Boolean values are passed through as is, to indicate success
2961          * of write queries or failure.
2962          *
2963          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2964          * resource, and it was necessary to call this function to convert it to
2965          * a wrapper. Nowadays, raw database objects are never exposed to external
2966          * callers, so this is unnecessary in external code. For compatibility with
2967          * old code, ResultWrapper objects are passed through unaltered.
2968          *
2969          * @param $result bool|ResultWrapper
2970          *
2971          * @return bool|ResultWrapper
2972          */
2973         function resultObject( $result ) {
2974                 if ( empty( $result ) ) {
2975                         return false;
2976                 } elseif ( $result instanceof ResultWrapper ) {
2977                         return $result;
2978                 } elseif ( $result === true ) {
2979                         // Successful write query
2980                         return $result;
2981                 } else {
2982                         return new ResultWrapper( $this, $result );
2983                 }
2984         }
2985
2986         /**
2987          * Return aggregated value alias
2988          *
2989          * @param $valuedata
2990          * @param $valuename string
2991          *
2992          * @return string
2993          */
2994         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2995                 return $valuename;
2996         }
2997
2998         /**
2999          * Ping the server and try to reconnect if it there is no connection
3000          *
3001          * @return bool Success or failure
3002          */
3003         function ping() {
3004                 # Stub.  Not essential to override.
3005                 return true;
3006         }
3007
3008         /**
3009          * Get slave lag. Currently supported only by MySQL.
3010          *
3011          * Note that this function will generate a fatal error on many
3012          * installations. Most callers should use LoadBalancer::safeGetLag()
3013          * instead.
3014          *
3015          * @return Database replication lag in seconds
3016          */
3017         function getLag() {
3018                 return intval( $this->mFakeSlaveLag );
3019         }
3020
3021         /**
3022          * Return the maximum number of items allowed in a list, or 0 for unlimited.
3023          *
3024          * @return int
3025          */
3026         function maxListLen() {
3027                 return 0;
3028         }
3029
3030         /**
3031          * Some DBMSs have a special format for inserting into blob fields, they
3032          * don't allow simple quoted strings to be inserted. To insert into such
3033          * a field, pass the data through this function before passing it to
3034          * DatabaseBase::insert().
3035          * @param $b string
3036          * @return string
3037          */
3038         function encodeBlob( $b ) {
3039                 return $b;
3040         }
3041
3042         /**
3043          * Some DBMSs return a special placeholder object representing blob fields
3044          * in result objects. Pass the object through this function to return the
3045          * original string.
3046          * @param $b string
3047          * @return string
3048          */
3049         function decodeBlob( $b ) {
3050                 return $b;
3051         }
3052
3053         /**
3054          * Override database's default connection timeout
3055          *
3056          * @param $timeout Integer in seconds
3057          * @return void
3058          * @deprecated since 1.19; use setSessionOptions()
3059          */
3060         public function setTimeout( $timeout ) {
3061                 wfDeprecated( __METHOD__, '1.19' );
3062                 $this->setSessionOptions( array( 'connTimeout' => $timeout ) );
3063         }
3064
3065         /**
3066          * Override database's default behavior. $options include:
3067          *     'connTimeout' : Set the connection timeout value in seconds.
3068          *                     May be useful for very long batch queries such as
3069          *                     full-wiki dumps, where a single query reads out over
3070          *                     hours or days.
3071          *
3072          * @param $options Array
3073          * @return void
3074          */
3075         public function setSessionOptions( array $options ) {}
3076
3077         /**
3078          * Read and execute SQL commands from a file.
3079          *
3080          * Returns true on success, error string or exception on failure (depending
3081          * on object's error ignore settings).
3082          *
3083          * @param $filename String: File name to open
3084          * @param $lineCallback Callback: Optional function called before reading each line
3085          * @param $resultCallback Callback: Optional function called for each MySQL result
3086          * @param $fname String: Calling function name or false if name should be
3087          *      generated dynamically using $filename
3088          * @return bool|string
3089          */
3090         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
3091                 wfSuppressWarnings();
3092                 $fp = fopen( $filename, 'r' );
3093                 wfRestoreWarnings();
3094
3095                 if ( false === $fp ) {
3096                         throw new MWException( "Could not open \"{$filename}\".\n" );
3097                 }
3098
3099                 if ( !$fname ) {
3100                         $fname = __METHOD__ . "( $filename )";
3101                 }
3102
3103                 try {
3104                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
3105                 }
3106                 catch ( MWException $e ) {
3107                         fclose( $fp );
3108                         throw $e;
3109                 }
3110
3111                 fclose( $fp );
3112
3113                 return $error;
3114         }
3115
3116         /**
3117          * Get the full path of a patch file. Originally based on archive()
3118          * from updaters.inc. Keep in mind this always returns a patch, as
3119          * it fails back to MySQL if no DB-specific patch can be found
3120          *
3121          * @param $patch String The name of the patch, like patch-something.sql
3122          * @return String Full path to patch file
3123          */
3124         public function patchPath( $patch ) {
3125                 global $IP;
3126
3127                 $dbType = $this->getType();
3128                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3129                         return "$IP/maintenance/$dbType/archives/$patch";
3130                 } else {
3131                         return "$IP/maintenance/archives/$patch";
3132                 }
3133         }
3134
3135         /**
3136          * Set variables to be used in sourceFile/sourceStream, in preference to the
3137          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3138          * all. If it's set to false, $GLOBALS will be used.
3139          *
3140          * @param $vars False, or array mapping variable name to value.
3141          */
3142         function setSchemaVars( $vars ) {
3143                 $this->mSchemaVars = $vars;
3144         }
3145
3146         /**
3147          * Read and execute commands from an open file handle.
3148          *
3149          * Returns true on success, error string or exception on failure (depending
3150          * on object's error ignore settings).
3151          *
3152          * @param $fp Resource: File handle
3153          * @param $lineCallback Callback: Optional function called before reading each line
3154          * @param $resultCallback Callback: Optional function called for each MySQL result
3155          * @param $fname String: Calling function name
3156          * @return bool|string
3157          */
3158         function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3159                 $fname = 'DatabaseBase::sourceStream' )
3160         {
3161                 $cmd = '';
3162                 $done = false;
3163
3164                 while ( !feof( $fp ) ) {
3165                         if ( $lineCallback ) {
3166                                 call_user_func( $lineCallback );
3167                         }
3168
3169                         $line = trim( fgets( $fp ) );
3170
3171                         if ( $line == '' ) {
3172                                 continue;
3173                         }
3174
3175                         if ( '-' == $line[0] && '-' == $line[1] ) {
3176                                 continue;
3177                         }
3178
3179                         if ( $cmd != '' ) {
3180                                 $cmd .= ' ';
3181                         }
3182
3183                         $done = $this->streamStatementEnd( $cmd, $line );
3184
3185                         $cmd .= "$line\n";
3186
3187                         if ( $done || feof( $fp ) ) {
3188                                 $cmd = $this->replaceVars( $cmd );
3189                                 $res = $this->query( $cmd, $fname );
3190
3191                                 if ( $resultCallback ) {
3192                                         call_user_func( $resultCallback, $res, $this );
3193                                 }
3194
3195                                 if ( false === $res ) {
3196                                         $err = $this->lastError();
3197                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3198                                 }
3199
3200                                 $cmd = '';
3201                                 $done = false;
3202                         }
3203                 }
3204
3205                 return true;
3206         }
3207
3208         /**
3209          * Called by sourceStream() to check if we've reached a statement end
3210          *
3211          * @param $sql String: SQL assembled so far
3212          * @param $newLine String: New line about to be added to $sql
3213          * @returns Bool: Whether $newLine contains end of the statement
3214          */
3215         protected function streamStatementEnd( &$sql, &$newLine ) {
3216                 if ( $this->delimiter ) {
3217                         $prev = $newLine;
3218                         $newLine = preg_replace( '/' . preg_quote( $this->delimiter, '/' ) . '$/', '', $newLine );
3219                         if ( $newLine != $prev ) {
3220                                 return true;
3221                         }
3222                 }
3223                 return false;
3224         }
3225
3226         /**
3227          * Database independent variable replacement. Replaces a set of variables
3228          * in an SQL statement with their contents as given by $this->getSchemaVars().
3229          *
3230          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3231          *
3232          * - '{$var}' should be used for text and is passed through the database's
3233          *   addQuotes method.
3234          * - `{$var}` should be used for identifiers (eg: table and database names),
3235          *   it is passed through the database's addIdentifierQuotes method which
3236          *   can be overridden if the database uses something other than backticks.
3237          * - / *$var* / is just encoded, besides traditional table prefix and
3238          *   table options its use should be avoided.
3239          *
3240          * @param $ins String: SQL statement to replace variables in
3241          * @return String The new SQL statement with variables replaced
3242          */
3243         protected function replaceSchemaVars( $ins ) {
3244                 $vars = $this->getSchemaVars();
3245                 foreach ( $vars as $var => $value ) {
3246                         // replace '{$var}'
3247                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3248                         // replace `{$var}`
3249                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3250                         // replace /*$var*/
3251                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ) , $ins );
3252                 }
3253                 return $ins;
3254         }
3255
3256         /**
3257          * Replace variables in sourced SQL
3258          *
3259          * @param $ins string
3260          *
3261          * @return string
3262          */
3263         protected function replaceVars( $ins ) {
3264                 $ins = $this->replaceSchemaVars( $ins );
3265
3266                 // Table prefixes
3267                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3268                         array( $this, 'tableNameCallback' ), $ins );
3269
3270                 // Index names
3271                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3272                         array( $this, 'indexNameCallback' ), $ins );
3273
3274                 return $ins;
3275         }
3276
3277         /**
3278          * Get schema variables. If none have been set via setSchemaVars(), then
3279          * use some defaults from the current object.
3280          *
3281          * @return array
3282          */
3283         protected function getSchemaVars() {
3284                 if ( $this->mSchemaVars ) {
3285                         return $this->mSchemaVars;
3286                 } else {
3287                         return $this->getDefaultSchemaVars();
3288                 }
3289         }
3290
3291         /**
3292          * Get schema variables to use if none have been set via setSchemaVars().
3293          *
3294          * Override this in derived classes to provide variables for tables.sql
3295          * and SQL patch files.
3296          *
3297          * @return array
3298          */
3299         protected function getDefaultSchemaVars() {
3300                 return array();
3301         }
3302
3303         /**
3304          * Table name callback
3305          *
3306          * @param $matches array
3307          *
3308          * @return string
3309          */
3310         protected function tableNameCallback( $matches ) {
3311                 return $this->tableName( $matches[1] );
3312         }
3313
3314         /**
3315          * Index name callback
3316          *
3317          * @param $matches array
3318          *
3319          * @return string
3320          */
3321         protected function indexNameCallback( $matches ) {
3322                 return $this->indexName( $matches[1] );
3323         }
3324
3325         /**
3326          * Build a concatenation list to feed into a SQL query
3327          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
3328          * @return String
3329          */
3330         function buildConcat( $stringList ) {
3331                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
3332         }
3333
3334         /**
3335          * Acquire a named lock
3336          *
3337          * Abstracted from Filestore::lock() so child classes can implement for
3338          * their own needs.
3339          *
3340          * @param $lockName String: name of lock to aquire
3341          * @param $method String: name of method calling us
3342          * @param $timeout Integer: timeout
3343          * @return Boolean
3344          */
3345         public function lock( $lockName, $method, $timeout = 5 ) {
3346                 return true;
3347         }
3348
3349         /**
3350          * Release a lock.
3351          *
3352          * @param $lockName String: Name of lock to release
3353          * @param $method String: Name of method calling us
3354          *
3355          * @return Returns 1 if the lock was released, 0 if the lock was not established
3356          * by this thread (in which case the lock is not released), and NULL if the named
3357          * lock did not exist
3358          */
3359         public function unlock( $lockName, $method ) {
3360                 return true;
3361         }
3362
3363         /**
3364          * Lock specific tables
3365          *
3366          * @param $read Array of tables to lock for read access
3367          * @param $write Array of tables to lock for write access
3368          * @param $method String name of caller
3369          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
3370          *
3371          * @return bool
3372          */
3373         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3374                 return true;
3375         }
3376
3377         /**
3378          * Unlock specific tables
3379          *
3380          * @param $method String the caller
3381          *
3382          * @return bool
3383          */
3384         public function unlockTables( $method ) {
3385                 return true;
3386         }
3387
3388         /**
3389          * Delete a table
3390          * @param $tableName string
3391          * @param $fName string
3392          * @return bool|ResultWrapper
3393          * @since 1.18
3394          */
3395         public function dropTable( $tableName, $fName = 'DatabaseBase::dropTable' ) {
3396                 if( !$this->tableExists( $tableName, $fName ) ) {
3397                         return false;
3398                 }
3399                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3400                 if( $this->cascadingDeletes() ) {
3401                         $sql .= " CASCADE";
3402                 }
3403                 return $this->query( $sql, $fName );
3404         }
3405
3406         /**
3407          * Get search engine class. All subclasses of this need to implement this
3408          * if they wish to use searching.
3409          *
3410          * @return String
3411          */
3412         public function getSearchEngine() {
3413                 return 'SearchEngineDummy';
3414         }
3415
3416         /**
3417          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3418          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3419          * because "i" sorts after all numbers.
3420          *
3421          * @return String
3422          */
3423         public function getInfinity() {
3424                 return 'infinity';
3425         }
3426
3427         /**
3428          * Encode an expiry time
3429          *
3430          * @param $expiry String: timestamp for expiry, or the 'infinity' string
3431          * @return String
3432          */
3433         public function encodeExpiry( $expiry ) {
3434                 if ( $expiry == '' || $expiry == $this->getInfinity() ) {
3435                         return $this->getInfinity();
3436                 } else {
3437                         return $this->timestamp( $expiry );
3438                 }
3439         }
3440
3441         /**
3442          * Allow or deny "big selects" for this session only. This is done by setting
3443          * the sql_big_selects session variable.
3444          *
3445          * This is a MySQL-specific feature.
3446          *
3447          * @param $value Mixed: true for allow, false for deny, or "default" to
3448          *   restore the initial value
3449          */
3450         public function setBigSelects( $value = true ) {
3451                 // no-op
3452         }
3453 }