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 SQL result 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 # ------------------------------------------------------------------------------
 228 # Accessors
 229 # ------------------------------------------------------------------------------
 230         # These optionally set a variable and return the previous state
 231
 232         /**
 233          * A string describing the current software version, and possibly
 234          * other details in a user-friendly way.  Will be listed on Special:Version, etc.
 235          * Use getServerVersion() to get machine-friendly information.
 236          *
 237          * @return string: Version information from the database server
 238          */
 239         public function getServerInfo() {
 240                 return $this->getServerVersion();
 241         }
 242
 243         /**
 244          * Boolean, controls output of large amounts of debug information.
 245          * @param $debug bool|null
 246          *   - true to enable debugging
 247          *   - false to disable debugging
 248          *   - omitted or null to do nothing
 249          *
 250          * @return The previous value of the flag
 251          */
 252         function debug( $debug = null ) {
 253                 return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
 254         }
 255
 256         /**
 257          * Turns buffering of SQL result sets on (true) or off (false). Default is
 258          * "on".
 259          *
 260          * Unbuffered queries are very troublesome in MySQL:
 261          *
 262          *   - If another query is executed while the first query is being read
 263          *     out, the first query is killed. This means you can't call normal
 264          *     MediaWiki functions while you are reading an unbuffered query result
 265          *     from a normal wfGetDB() connection.
 266          *
 267          *   - Unbuffered queries cause the MySQL server to use large amounts of
 268          *     memory and to hold broad locks which block other queries.
 269          *
 270          * If you want to limit client-side memory, it's almost always better to
 271          * split up queries into batches using a LIMIT clause than to switch off
 272          * buffering.
 273          *
 274          * @param $buffer null|bool
 275          *
 276          * @return The previous value of the flag
 277          */
 278         function bufferResults( $buffer = null ) {
 279                 if ( is_null( $buffer ) ) {
 280                         return !(bool)( $this->mFlags & DBO_NOBUFFER );
 281                 } else {
 282                         return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
 283                 }
 284         }
 285
 286         /**
 287          * Turns on (false) or off (true) the automatic generation and sending
 288          * of a "we're sorry, but there has been a database error" page on
 289          * database errors. Default is on (false). When turned off, the
 290          * code should use lastErrno() and lastError() to handle the
 291          * situation as appropriate.
 292          *
 293          * @param $ignoreErrors
 294          *
 295          * @return The previous value of the flag.
 296          */
 297         function ignoreErrors( $ignoreErrors = null ) {
 298                 return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 299         }
 300
 301         /**
 302          * Gets or sets the current transaction level.
 303          *
 304          * Historically, transactions were allowed to be "nested". This is no
 305          * longer supported, so this function really only returns a boolean.
 306          *
 307          * @param $level An integer (0 or 1), or omitted to leave it unchanged.
 308          * @return The previous value
 309          */
 310         function trxLevel( $level = null ) {
 311                 return wfSetVar( $this->mTrxLevel, $level );
 312         }
 313
 314         /**
 315          * Get/set the number of errors logged. Only useful when errors are ignored
 316          * @param $count The count to set, or omitted to leave it unchanged.
 317          * @return The error count
 318          */
 319         function errorCount( $count = null ) {
 320                 return wfSetVar( $this->mErrorCount, $count );
 321         }
 322
 323         /**
 324          * Get/set the table prefix.
 325          * @param $prefix The table prefix to set, or omitted to leave it unchanged.
 326          * @return The previous table prefix.
 327          */
 328         function tablePrefix( $prefix = null ) {
 329                 return wfSetVar( $this->mTablePrefix, $prefix );
 330         }
 331
 332         /**
 333          * Get properties passed down from the server info array of the load
 334          * balancer.
 335          *
 336          * @param $name string The entry of the info array to get, or null to get the
 337          *   whole array
 338          *
 339          * @return LoadBalancer|null
 340          */
 341         function getLBInfo( $name = null ) {
 342                 if ( is_null( $name ) ) {
 343                         return $this->mLBInfo;
 344                 } else {
 345                         if ( array_key_exists( $name, $this->mLBInfo ) ) {
 346                                 return $this->mLBInfo[$name];
 347                         } else {
 348                                 return null;
 349                         }
 350                 }
 351         }
 352
 353         /**
 354          * Set the LB info array, or a member of it. If called with one parameter,
 355          * the LB info array is set to that parameter. If it is called with two
 356          * parameters, the member with the given name is set to the given value.
 357          *
 358          * @param $name
 359          * @param $value
 360          */
 361         function setLBInfo( $name, $value = null ) {
 362                 if ( is_null( $value ) ) {
 363                         $this->mLBInfo = $name;
 364                 } else {
 365                         $this->mLBInfo[$name] = $value;
 366                 }
 367         }
 368
 369         /**
 370          * Set lag time in seconds for a fake slave
 371          *
 372          * @param $lag int
 373          */
 374         function setFakeSlaveLag( $lag ) {
 375                 $this->mFakeSlaveLag = $lag;
 376         }
 377
 378         /**
 379          * Make this connection a fake master
 380          *
 381          * @param $enabled bool
 382          */
 383         function setFakeMaster( $enabled = true ) {
 384                 $this->mFakeMaster = $enabled;
 385         }
 386
 387         /**
 388          * Returns true if this database supports (and uses) cascading deletes
 389          *
 390          * @return bool
 391          */
 392         function cascadingDeletes() {
 393                 return false;
 394         }
 395
 396         /**
 397          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 398          *
 399          * @return bool
 400          */
 401         function cleanupTriggers() {
 402                 return false;
 403         }
 404
 405         /**
 406          * Returns true if this database is strict about what can be put into an IP field.
 407          * Specifically, it uses a NULL value instead of an empty string.
 408          *
 409          * @return bool
 410          */
 411         function strictIPs() {
 412                 return false;
 413         }
 414
 415         /**
 416          * Returns true if this database uses timestamps rather than integers
 417          *
 418          * @return bool
 419         */
 420         function realTimestamps() {
 421                 return false;
 422         }
 423
 424         /**
 425          * Returns true if this database does an implicit sort when doing GROUP BY
 426          *
 427          * @return bool
 428          */
 429         function implicitGroupby() {
 430                 return true;
 431         }
 432
 433         /**
 434          * Returns true if this database does an implicit order by when the column has an index
 435          * For example: SELECT page_title FROM page LIMIT 1
 436          */
 437         function implicitOrderby() {
 438                 return true;
 439         }
 440
 441         /**
 442          * Returns true if this database requires that SELECT DISTINCT queries require that all
 443            ORDER BY expressions occur in the SELECT list per the SQL92 standard
 444          *
 445          * @return bool
 446          */
 447         function standardSelectDistinct() {
 448                 return true;
 449         }
 450
 451         /**
 452          * Returns true if this database can do a native search on IP columns
 453          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 454          *
 455          * @return bool
 456          */
 457         function searchableIPs() {
 458                 return false;
 459         }
 460
 461         /**
 462          * Returns true if this database can use functional indexes
 463          *
 464          * @return bool
 465          */
 466         function functionalIndexes() {
 467                 return false;
 468         }
 469
 470         /**
 471          * Return the last query that went through DatabaseBase::query()
 472          * @return String
 473          */
 474         function lastQuery() {
 475                 return $this->mLastQuery;
 476         }
 477
 478         /**
 479          * Returns true if the connection may have been used for write queries.
 480          * Should return true if unsure.
 481          *
 482          * @return bool
 483          */
 484         function doneWrites() {
 485                 return $this->mDoneWrites;
 486         }
 487
 488         /**
 489          * Is a connection to the database open?
 490          * @return Boolean
 491          */
 492         function isOpen() {
 493                 return $this->mOpened;
 494         }
 495
 496         /**
 497          * Set a flag for this connection
 498          *
 499          * @param $flag Integer: DBO_* constants from Defines.php:
 500          *   - DBO_DEBUG: output some debug info (same as debug())
 501          *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
 502          *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
 503          *   - DBO_TRX: automatically start transactions
 504          *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
 505          *       and removes it in command line mode
 506          *   - DBO_PERSISTENT: use persistant database connection
 507          */
 508         function setFlag( $flag ) {
 509                 $this->mFlags |= $flag;
 510         }
 511
 512         /**
 513          * Clear a flag for this connection
 514          *
 515          * @param $flag: same as setFlag()'s $flag param
 516          */
 517         function clearFlag( $flag ) {
 518                 $this->mFlags &= ~$flag;
 519         }
 520
 521         /**
 522          * Returns a boolean whether the flag $flag is set for this connection
 523          *
 524          * @param $flag: same as setFlag()'s $flag param
 525          * @return Boolean
 526          */
 527         function getFlag( $flag ) {
 528                 return !!( $this->mFlags & $flag );
 529         }
 530
 531         /**
 532          * General read-only accessor
 533          */
 534         function getProperty( $name ) {
 535                 return $this->$name;
 536         }
 537
 538         /**
 539          * @return string
 540          */
 541         function getWikiID() {
 542                 if ( $this->mTablePrefix ) {
 543                         return "{$this->mDBname}-{$this->mTablePrefix}";
 544                 } else {
 545                         return $this->mDBname;
 546                 }
 547         }
 548
 549         /**
 550          * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
 551          *
 552          * @return string
 553          */
 554         public function getSchemaPath() {
 555                 global $IP;
 556                 if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
 557                         return "$IP/maintenance/" . $this->getType() . "/tables.sql";
 558                 } else {
 559                         return "$IP/maintenance/tables.sql";
 560                 }
 561         }
 562
 563 # ------------------------------------------------------------------------------
 564 # Other functions
 565 # ------------------------------------------------------------------------------
 566
 567         /**
 568          * Constructor.
 569          * @param $server String: database server host
 570          * @param $user String: database user name
 571          * @param $password String: database user password
 572          * @param $dbName String: database name
 573          * @param $flags
 574          * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
 575          */
 576         function __construct( $server = false, $user = false, $password = false, $dbName = false,
 577                 $flags = 0, $tablePrefix = 'get from global'
 578         ) {
 579                 global $wgDBprefix, $wgCommandLineMode;
 580
 581                 $this->mFlags = $flags;
 582
 583                 if ( $this->mFlags & DBO_DEFAULT ) {
 584                         if ( $wgCommandLineMode ) {
 585                                 $this->mFlags &= ~DBO_TRX;
 586                         } else {
 587                                 $this->mFlags |= DBO_TRX;
 588                         }
 589                 }
 590
 591                 /** Get the default table prefix*/
 592                 if ( $tablePrefix == 'get from global' ) {
 593                         $this->mTablePrefix = $wgDBprefix;
 594                 } else {
 595                         $this->mTablePrefix = $tablePrefix;
 596                 }
 597
 598                 if ( $user ) {
 599                         $this->open( $server, $user, $password, $dbName );
 600                 }
 601         }
 602
 603         /**
 604          * Same as new DatabaseMysql( ... ), kept for backward compatibility
 605          * @deprecated since 1.17
 606          *
 607          * @return DatabaseMysql
 608          */
 609         static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
 610                 wfDeprecated( __METHOD__ );
 611                 return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
 612         }
 613
 614         /**
 615          * Given a DB type, construct the name of the appropriate child class of
 616          * DatabaseBase. This is designed to replace all of the manual stuff like:
 617          *      $class = 'Database' . ucfirst( strtolower( $type ) );
 618          * as well as validate against the canonical list of DB types we have
 619          *
 620          * This factory function is mostly useful for when you need to connect to a
 621          * database other than the MediaWiki default (such as for external auth,
 622          * an extension, et cetera). Do not use this to connect to the MediaWiki
 623          * database. Example uses in core:
 624          * @see LoadBalancer::reallyOpenConnection()
 625          * @see ExternalUser_MediaWiki::initFromCond()
 626          * @see ForeignDBRepo::getMasterDB()
 627          * @see WebInstaller_DBConnect::execute()
 628          *
 629          * @param $dbType String A possible DB type
 630          * @param $p Array An array of options to pass to the constructor.
 631          *    Valid options are: host, user, password, dbname, flags, tablePrefix
 632          * @return DatabaseBase subclass or null
 633          */
 634         public final static function factory( $dbType, $p = array() ) {
 635                 $canonicalDBTypes = array(
 636                         'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
 637                 );
 638                 $dbType = strtolower( $dbType );
 639
 640                 if( in_array( $dbType, $canonicalDBTypes ) ) {
 641                         $class = 'Database' . ucfirst( $dbType );
 642                         return new $class(
 643                                 isset( $p['host'] ) ? $p['host'] : false,
 644                                 isset( $p['user'] ) ? $p['user'] : false,
 645                                 isset( $p['password'] ) ? $p['password'] : false,
 646                                 isset( $p['dbname'] ) ? $p['dbname'] : false,
 647                                 isset( $p['flags'] ) ? $p['flags'] : 0,
 648                                 isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
 649                         );
 650                 } else {
 651                         return null;
 652                 }
 653         }
 654
 655         protected function installErrorHandler() {
 656                 $this->mPHPError = false;
 657                 $this->htmlErrors = ini_set( 'html_errors', '0' );
 658                 set_error_handler( array( $this, 'connectionErrorHandler' ) );
 659         }
 660
 661         /**
 662          * @return bool|string
 663          */
 664         protected function restoreErrorHandler() {
 665                 restore_error_handler();
 666                 if ( $this->htmlErrors !== false ) {
 667                         ini_set( 'html_errors', $this->htmlErrors );
 668                 }
 669                 if ( $this->mPHPError ) {
 670                         $error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
 671                         $error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
 672                         return $error;
 673                 } else {
 674                         return false;
 675                 }
 676         }
 677
 678         protected function connectionErrorHandler( $errno,  $errstr ) {
 679                 $this->mPHPError = $errstr;
 680         }
 681
 682         /**
 683          * Closes a database connection.
 684          * if it is open : commits any open transactions
 685          *
 686          * @return Bool operation success. true if already closed.
 687          */
 688         function close() {
 689                 # Stub, should probably be overridden
 690                 return true;
 691         }
 692
 693         /**
 694          * @param $error String: fallback error message, used if none is given by DB
 695          */
 696         function reportConnectionError( $error = 'Unknown error' ) {
 697                 $myError = $this->lastError();
 698                 if ( $myError ) {
 699                         $error = $myError;
 700                 }
 701
 702                 # New method
 703                 throw new DBConnectionError( $this, $error );
 704         }
 705
 706         /**
 707          * The DBMS-dependent part of query()
 708          *
 709          * @param  $sql String: SQL query.
 710          * @return Result object to feed to fetchObject, fetchRow, ...; or false on failure
 711          */
 712         protected abstract function doQuery( $sql );
 713
 714         /**
 715          * Determine whether a query writes to the DB.
 716          * Should return true if unsure.
 717          *
 718          * @param $sql string
 719          *
 720          * @return bool
 721          */
 722         function isWriteQuery( $sql ) {
 723                 return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
 724         }
 725
 726         /**
 727          * Run an SQL query and return the result. Normally throws a DBQueryError
 728          * on failure. If errors are ignored, returns false instead.
 729          *
 730          * In new code, the query wrappers select(), insert(), update(), delete(),
 731          * etc. should be used where possible, since they give much better DBMS
 732          * independence and automatically quote or validate user input in a variety
 733          * of contexts. This function is generally only useful for queries which are
 734          * explicitly DBMS-dependent and are unsupported by the query wrappers, such
 735          * as CREATE TABLE.
 736          *
 737          * However, the query wrappers themselves should call this function.
 738          *
 739          * @param  $sql        String: SQL query
 740          * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
 741          *     comment (you can use __METHOD__ or add some extra info)
 742          * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
 743          *     maybe best to catch the exception instead?
 744          * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
 745          *     for a successful read query, or false on failure if $tempIgnore set
 746          * @throws DBQueryError Thrown when the database returns an error of any kind
 747          */
 748         public function query( $sql, $fname = '', $tempIgnore = false ) {
 749                 $isMaster = !is_null( $this->getLBInfo( 'master' ) );
 750                 if ( !Profiler::instance()->isStub() ) {
 751                         # generalizeSQL will probably cut down the query to reasonable
 752                         # logging size most of the time. The substr is really just a sanity check.
 753
 754                         if ( $isMaster ) {
 755                                 $queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 756                                 $totalProf = 'DatabaseBase::query-master';
 757                         } else {
 758                                 $queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
 759                                 $totalProf = 'DatabaseBase::query';
 760                         }
 761
 762                         wfProfileIn( $totalProf );
 763                         wfProfileIn( $queryProf );
 764                 }
 765
 766                 $this->mLastQuery = $sql;
 767                 if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
 768                         # Set a flag indicating that writes have been done
 769                         wfDebug( __METHOD__ . ": Writes done: $sql\n" );
 770                         $this->mDoneWrites = true;
 771                 }
 772
 773                 # Add a comment for easy SHOW PROCESSLIST interpretation
 774                 global $wgUser;
 775                 if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
 776                         $userName = $wgUser->getName();
 777                         if ( mb_strlen( $userName ) > 15 ) {
 778                                 $userName = mb_substr( $userName, 0, 15 ) . '...';
 779                         }
 780                         $userName = str_replace( '/', '', $userName );
 781                 } else {
 782                         $userName = '';
 783                 }
 784                 $commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );
 785
 786                 # If DBO_TRX is set, start a transaction
 787                 if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
 788                         $sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
 789                         # avoid establishing transactions for SHOW and SET statements too -
 790                         # that would delay transaction initializations to once connection
 791                         # is really used by application
 792                         $sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
 793                         if ( strpos( $sqlstart, "SHOW " ) !== 0 and strpos( $sqlstart, "SET " ) !== 0 )
 794                                 $this->begin();
 795                 }
 796
 797                 if ( $this->debug() ) {
 798                         static $cnt = 0;
 799
 800                         $cnt++;
 801                         $sqlx = substr( $commentedSql, 0, 500 );
 802                         $sqlx = strtr( $sqlx, "\t\n", '  ' );
 803
 804                         if ( $isMaster ) {
 805                                 wfDebug( "Query $cnt (master): $sqlx\n" );
 806                         } else {
 807                                 wfDebug( "Query $cnt (slave): $sqlx\n" );
 808                         }
 809                 }
 810
 811                 if ( istainted( $sql ) & TC_MYSQL ) {
 812                         throw new MWException( 'Tainted query found' );
 813                 }
 814
 815                 # Do the query and handle errors
 816                 $ret = $this->doQuery( $commentedSql );
 817
 818                 # Try reconnecting if the connection was lost
 819                 if ( false === $ret && $this->wasErrorReissuable() ) {
 820                         # Transaction is gone, like it or not
 821                         $this->mTrxLevel = 0;
 822                         wfDebug( "Connection lost, reconnecting...\n" );
 823
 824                         if ( $this->ping() ) {
 825                                 wfDebug( "Reconnected\n" );
 826                                 $sqlx = substr( $commentedSql, 0, 500 );
 827                                 $sqlx = strtr( $sqlx, "\t\n", '  ' );
 828                                 global $wgRequestTime;
 829                                 $elapsed = round( microtime( true ) - $wgRequestTime, 3 );
 830                                 if ( $elapsed < 300 ) {
 831                                         # Not a database error to lose a transaction after a minute or two
 832                                         wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
 833                                 }
 834                                 $ret = $this->doQuery( $commentedSql );
 835                         } else {
 836                                 wfDebug( "Failed\n" );
 837                         }
 838                 }
 839
 840                 if ( false === $ret ) {
 841                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
 842                 }
 843
 844                 if ( !Profiler::instance()->isStub() ) {
 845                         wfProfileOut( $queryProf );
 846                         wfProfileOut( $totalProf );
 847                 }
 848
 849                 return $this->resultObject( $ret );
 850         }
 851
 852         /**
 853          * Report a query error. Log the error, and if neither the object ignore
 854          * flag nor the $tempIgnore flag is set, throw a DBQueryError.
 855          *
 856          * @param $error String
 857          * @param $errno Integer
 858          * @param $sql String
 859          * @param $fname String
 860          * @param $tempIgnore Boolean
 861          */
 862         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 863                 # Ignore errors during error handling to avoid infinite recursion
 864                 $ignore = $this->ignoreErrors( true );
 865                 ++$this->mErrorCount;
 866
 867                 if ( $ignore || $tempIgnore ) {
 868                         wfDebug( "SQL ERROR (ignored): $error\n" );
 869                         $this->ignoreErrors( $ignore );
 870                 } else {
 871                         $sql1line = str_replace( "\n", "\\n", $sql );
 872                         wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
 873                         wfDebug( "SQL ERROR: " . $error . "\n" );
 874                         throw new DBQueryError( $this, $error, $errno, $sql, $fname );
 875                 }
 876         }
 877
 878         /**
 879          * Intended to be compatible with the PEAR::DB wrapper functions.
 880          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
 881          *
 882          * ? = scalar value, quoted as necessary
 883          * ! = raw SQL bit (a function for instance)
 884          * & = filename; reads the file and inserts as a blob
 885          *     (we don't use this though...)
 886          *
 887          * This function should not be used directly by new code outside of the
 888          * database classes. The query wrapper functions (select() etc.) should be
 889          * used instead.
 890          *
 891          * @param $sql string
 892          * @param $func string
 893          *
 894          * @return array
 895          */
 896         function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
 897                 /* MySQL doesn't support prepared statements (yet), so just
 898                    pack up the query for reference. We'll manually replace
 899                    the bits later. */
 900                 return array( 'query' => $sql, 'func' => $func );
 901         }
 902
 903         /**
 904          * Free a prepared query, generated by prepare().
 905          */
 906         function freePrepared( $prepared ) {
 907                 /* No-op by default */
 908         }
 909
 910         /**
 911          * Execute a prepared query with the various arguments
 912          * @param $prepared String: the prepared sql
 913          * @param $args Mixed: Either an array here, or put scalars as varargs
 914          *
 915          * @return ResultWrapper
 916          */
 917         function execute( $prepared, $args = null ) {
 918                 if ( !is_array( $args ) ) {
 919                         # Pull the var args
 920                         $args = func_get_args();
 921                         array_shift( $args );
 922                 }
 923
 924                 $sql = $this->fillPrepared( $prepared['query'], $args );
 925
 926                 return $this->query( $sql, $prepared['func'] );
 927         }
 928
 929         /**
 930          * Prepare & execute an SQL statement, quoting and inserting arguments
 931          * in the appropriate places.
 932          *
 933          * This function should not be used directly by new code outside of the
 934          * database classes. The query wrapper functions (select() etc.) should be
 935          * used instead.
 936          *
 937          * @param $query String
 938          * @param $args ...
 939          *
 940          * @return ResultWrapper
 941          */
 942         function safeQuery( $query, $args = null ) {
 943                 $prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );
 944
 945                 if ( !is_array( $args ) ) {
 946                         # Pull the var args
 947                         $args = func_get_args();
 948                         array_shift( $args );
 949                 }
 950
 951                 $retval = $this->execute( $prepared, $args );
 952                 $this->freePrepared( $prepared );
 953
 954                 return $retval;
 955         }
 956
 957         /**
 958          * For faking prepared SQL statements on DBs that don't support
 959          * it directly.
 960          * @param $preparedQuery String: a 'preparable' SQL statement
 961          * @param $args Array of arguments to fill it with
 962          * @return string executable SQL
 963          */
 964         function fillPrepared( $preparedQuery, $args ) {
 965                 reset( $args );
 966                 $this->preparedArgs =& $args;
 967
 968                 return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
 969                         array( &$this, 'fillPreparedArg' ), $preparedQuery );
 970         }
 971
 972         /**
 973          * preg_callback func for fillPrepared()
 974          * The arguments should be in $this->preparedArgs and must not be touched
 975          * while we're doing this.
 976          *
 977          * @param $matches Array
 978          * @return String
 979          */
 980         function fillPreparedArg( $matches ) {
 981                 switch( $matches[1] ) {
 982                         case '\\?': return '?';
 983                         case '\\!': return '!';
 984                         case '\\&': return '&';
 985                 }
 986
 987                 list( /* $n */ , $arg ) = each( $this->preparedArgs );
 988
 989                 switch( $matches[1] ) {
 990                         case '?': return $this->addQuotes( $arg );
 991                         case '!': return $arg;
 992                         case '&':
 993                                 # return $this->addQuotes( file_get_contents( $arg ) );
 994                                 throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
 995                         default:
 996                                 throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
 997                 }
 998         }
 999
1000         /**
1001          * Free a result object returned by query() or select(). It's usually not
1002          * necessary to call this, just use unset() or let the variable holding
1003          * the result object go out of scope.
1004          *
1005          * @param $res Mixed: A SQL result
1006          */
1007         function freeResult( $res ) {
1008         }
1009
1010         /**
1011          * Simple UPDATE wrapper.
1012          * Usually throws a DBQueryError on failure.
1013          * If errors are explicitly ignored, returns success
1014          *
1015          * This function exists for historical reasons, DatabaseBase::update() has a more standard
1016          * calling convention and feature set
1017          *
1018          * @param $table string
1019          * @param $var
1020          * @param $value
1021          * @param $cond
1022          * @param $fname string
1023          *
1024          * @return bool
1025          */
1026         function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
1027                 $table = $this->tableName( $table );
1028                 $sql = "UPDATE $table SET $var = '" .
1029                   $this->strencode( $value ) . "' WHERE ($cond)";
1030
1031                 return (bool)$this->query( $sql, $fname );
1032         }
1033
1034         /**
1035          * A SELECT wrapper which returns a single field from a single result row.
1036          *
1037          * Usually throws a DBQueryError on failure. If errors are explicitly
1038          * ignored, returns false on failure.
1039          *
1040          * If no result rows are returned from the query, false is returned.
1041          *
1042          * @param $table string|array Table name. See DatabaseBase::select() for details.
1043          * @param $var string The field name to select. This must be a valid SQL
1044          *   fragment: do not use unvalidated user input.
1045          * @param $cond string|array The condition array. See DatabaseBase::select() for details.
1046          * @param $fname string The function name of the caller.
1047          * @param $options string|array The query options. See DatabaseBase::select() for details.
1048          *
1049          * @return false|mixed The value from the field, or false on failure.
1050          */
1051         function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
1052                 $options = array() )
1053         {
1054                 if ( !is_array( $options ) ) {
1055                         $options = array( $options );
1056                 }
1057
1058                 $options['LIMIT'] = 1;
1059
1060                 $res = $this->select( $table, $var, $cond, $fname, $options );
1061
1062                 if ( $res === false || !$this->numRows( $res ) ) {
1063                         return false;
1064                 }
1065
1066                 $row = $this->fetchRow( $res );
1067
1068                 if ( $row !== false ) {
1069                         return reset( $row );
1070                 } else {
1071                         return false;
1072                 }
1073         }
1074
1075         /**
1076          * Returns an optional USE INDEX clause to go after the table, and a
1077          * string to go at the end of the query.
1078          *
1079          * @param $options Array: associative array of options to be turned into
1080          *              an SQL query, valid keys are listed in the function.
1081          * @return Array
1082          * @see DatabaseBase::select()
1083          */
1084         function makeSelectOptions( $options ) {
1085                 $preLimitTail = $postLimitTail = '';
1086                 $startOpts = '';
1087
1088                 $noKeyOptions = array();
1089
1090                 foreach ( $options as $key => $option ) {
1091                         if ( is_numeric( $key ) ) {
1092                                 $noKeyOptions[$option] = true;
1093                         }
1094                 }
1095
1096                 if ( isset( $options['GROUP BY'] ) ) {
1097                         $gb = is_array( $options['GROUP BY'] )
1098                                 ? implode( ',', $options['GROUP BY'] )
1099                                 : $options['GROUP BY'];
1100                         $preLimitTail .= " GROUP BY {$gb}";
1101                 }
1102
1103                 if ( isset( $options['HAVING'] ) ) {
1104                         $preLimitTail .= " HAVING {$options['HAVING']}";
1105                 }
1106
1107                 if ( isset( $options['ORDER BY'] ) ) {
1108                         $ob = is_array( $options['ORDER BY'] )
1109                                 ? implode( ',', $options['ORDER BY'] )
1110                                 : $options['ORDER BY'];
1111                         $preLimitTail .= " ORDER BY {$ob}";
1112                 }
1113
1114                 // if (isset($options['LIMIT'])) {
1115                 //      $tailOpts .= $this->limitResult('', $options['LIMIT'],
1116                 //              isset($options['OFFSET']) ? $options['OFFSET']
1117                 //              : false);
1118                 // }
1119
1120                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1121                         $postLimitTail .= ' FOR UPDATE';
1122                 }
1123
1124                 if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
1125                         $postLimitTail .= ' LOCK IN SHARE MODE';
1126                 }
1127
1128                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1129                         $startOpts .= 'DISTINCT';
1130                 }
1131
1132                 # Various MySQL extensions
1133                 if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
1134                         $startOpts .= ' /*! STRAIGHT_JOIN */';
1135                 }
1136
1137                 if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
1138                         $startOpts .= ' HIGH_PRIORITY';
1139                 }
1140
1141                 if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
1142                         $startOpts .= ' SQL_BIG_RESULT';
1143                 }
1144
1145                 if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
1146                         $startOpts .= ' SQL_BUFFER_RESULT';
1147                 }
1148
1149                 if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
1150                         $startOpts .= ' SQL_SMALL_RESULT';
1151                 }
1152
1153                 if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
1154                         $startOpts .= ' SQL_CALC_FOUND_ROWS';
1155                 }
1156
1157                 if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
1158                         $startOpts .= ' SQL_CACHE';
1159                 }
1160
1161                 if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
1162                         $startOpts .= ' SQL_NO_CACHE';
1163                 }
1164
1165                 if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
1166                         $useIndex = $this->useIndexClause( $options['USE INDEX'] );
1167                 } else {
1168                         $useIndex = '';
1169                 }
1170
1171                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1172         }
1173
1174         /**
1175          * Execute a SELECT query constructed using the various parameters provided.
1176          * See below for full details of the parameters.
1177          *
1178          * @param $table String|Array Table name
1179          * @param $vars String|Array Field names
1180          * @param $conds String|Array Conditions
1181          * @param $fname String Caller function name
1182          * @param $options Array Query options
1183          * @param $join_conds Array Join conditions
1184          *
1185          *
1186          * @param $table string|array
1187          *
1188          * May be either an array of table names, or a single string holding a table
1189          * name. If an array is given, table aliases can be specified, for example:
1190          *
1191          *    array( 'a' => 'user' )
1192          *
1193          * This includes the user table in the query, with the alias "a" available
1194          * for use in field names (e.g. a.user_name).
1195          *
1196          * All of the table names given here are automatically run through
1197          * DatabaseBase::tableName(), which causes the table prefix (if any) to be
1198          * added, and various other table name mappings to be performed.
1199          *
1200          *
1201          * @param $vars string|array
1202          *
1203          * May be either a field name or an array of field names. The field names
1204          * here are complete fragments of SQL, for direct inclusion into the SELECT
1205          * query. Expressions and aliases may be specified as in SQL, for example:
1206          *
1207          *   array( 'MAX(rev_id) AS maxrev' )
1208          *
1209          * If an expression is given, care must be taken to ensure that it is
1210          * DBMS-independent.
1211          *
1212          *
1213          * @param $conds string|array
1214          *
1215          * May be either a string containing a single condition, or an array of
1216          * conditions. If an array is given, the conditions constructed from each
1217          * element are combined with AND.
1218          *
1219          * Array elements may take one of two forms:
1220          *
1221          *   - Elements with a numeric key are interpreted as raw SQL fragments.
1222          *   - Elements with a string key are interpreted as equality conditions,
1223          *     where the key is the field name.
1224          *     - If the value of such an array element is a scalar (such as a
1225          *       string), it will be treated as data and thus quoted appropriately.
1226          *       If it is null, an IS NULL clause will be added.
1227          *     - If the value is an array, an IN(...) clause will be constructed,
1228          *       such that the field name may match any of the elements in the
1229          *       array. The elements of the array will be quoted.
1230          *     - If the field name ends with "!", this is taken as a flag which
1231          *       inverts the comparison, allowing NOT IN clauses to be constructed,
1232          *       for example: array( 'user_id!' => array( 1, 2, 3 ) )
1233          *
1234          * Note that expressions are often DBMS-dependent in their syntax.
1235          * DBMS-independent wrappers are provided for constructing several types of
1236          * expression commonly used in condition queries. See:
1237          *    - DatabaseBase::buildLike()
1238          *    - DatabaseBase::conditional()
1239          *
1240          *
1241          * @param $options string|array
1242          *
1243          * Optional: Array of query options. Boolean options are specified by
1244          * including them in the array as a string value with a numeric key, for
1245          * example:
1246          *
1247          *    array( 'FOR UPDATE' )
1248          *
1249          * The supported options are:
1250          *
1251          *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
1252          *     with LIMIT can theoretically be used for paging through a result set,
1253          *     but this is discouraged in MediaWiki for performance reasons.
1254          *
1255          *   - LIMIT: Integer: return at most this many rows. The rows are sorted
1256          *     and then the first rows are taken until the limit is reached. LIMIT
1257          *     is applied to a result set after OFFSET.
1258          *
1259          *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
1260          *     changed until the next COMMIT.
1261          *
1262          *   - DISTINCT: Boolean: return only unique result rows.
1263          *
1264          *   - GROUP BY: May be either an SQL fragment string naming a field or
1265          *     expression to group by, or an array of such SQL fragments.
1266          *
1267          *   - HAVING: A string containing a HAVING clause.
1268          *
1269          *   - ORDER BY: May be either an SQL fragment giving a field name or
1270          *     expression to order by, or an array of such SQL fragments.
1271          *
1272          *   - USE INDEX: This may be either a string giving the index name to use
1273          *     for the query, or an array. If it is an associative array, each key
1274          *     gives the table name (or alias), each value gives the index name to
1275          *     use for that table. All strings are SQL fragments and so should be
1276          *     validated by the caller.
1277          *
1278          *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
1279          *     instead of SELECT.
1280          *
1281          * And also the following boolean MySQL extensions, see the MySQL manual
1282          * for documentation:
1283          *
1284          *    - LOCK IN SHARE MODE
1285          *    - STRAIGHT_JOIN
1286          *    - HIGH_PRIORITY
1287          *    - SQL_BIG_RESULT
1288          *    - SQL_BUFFER_RESULT
1289          *    - SQL_SMALL_RESULT
1290          *    - SQL_CALC_FOUND_ROWS
1291          *    - SQL_CACHE
1292          *    - SQL_NO_CACHE
1293          *
1294          *
1295          * @param $join_conds string|array
1296          *
1297          * Optional associative array of table-specific join conditions. In the
1298          * most common case, this is unnecessary, since the join condition can be
1299          * in $conds. However, it is useful for doing a LEFT JOIN.
1300          *
1301          * The key of the array contains the table name or alias. The value is an
1302          * array with two elements, numbered 0 and 1. The first gives the type of
1303          * join, the second is an SQL fragment giving the join condition for that
1304          * table. For example:
1305          *
1306          *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1307          *
1308          * @return ResultWrapper. If the query returned no rows, a ResultWrapper
1309          *   with no rows in it will be returned. If there was a query error, a
1310          *   DBQueryError exception will be thrown, except if the "ignore errors"
1311          *   option was set, in which case false will be returned.
1312          */
1313         function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
1314                 $options = array(), $join_conds = array() ) {
1315                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
1316
1317                 return $this->query( $sql, $fname );
1318         }
1319
1320         /**
1321          * The equivalent of DatabaseBase::select() except that the constructed SQL
1322          * is returned, instead of being immediately executed.
1323          *
1324          * @param $table string|array Table name
1325          * @param $vars string|array Field names
1326          * @param $conds string|array Conditions
1327          * @param $fname string Caller function name
1328          * @param $options string|array Query options
1329          * @param $join_conds string|array Join conditions
1330          *
1331          * @return SQL query string.
1332          * @see DatabaseBase::select()
1333          */
1334         function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
1335                 if ( is_array( $vars ) ) {
1336                         $vars = implode( ',', $vars );
1337                 }
1338
1339                 $options = (array)$options;
1340
1341                 if ( is_array( $table ) ) {
1342                         $useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
1343                                 ? $options['USE INDEX']
1344                                 : array();
1345                         if ( count( $join_conds ) || count( $useIndex ) ) {
1346                                 $from = ' FROM ' .
1347                                         $this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
1348                         } else {
1349                                 $from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
1350                         }
1351                 } elseif ( $table != '' ) {
1352                         if ( $table { 0 } == ' ' ) {
1353                                 $from = ' FROM ' . $table;
1354                         } else {
1355                                 $from = ' FROM ' . $this->tableName( $table );
1356                         }
1357                 } else {
1358                         $from = '';
1359                 }
1360
1361                 list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );
1362
1363                 if ( !empty( $conds ) ) {
1364                         if ( is_array( $conds ) ) {
1365                                 $conds = $this->makeList( $conds, LIST_AND );
1366                         }
1367                         $sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
1368                 } else {
1369                         $sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
1370                 }
1371
1372                 if ( isset( $options['LIMIT'] ) ) {
1373                         $sql = $this->limitResult( $sql, $options['LIMIT'],
1374                                 isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
1375                 }
1376                 $sql = "$sql $postLimitTail";
1377
1378                 if ( isset( $options['EXPLAIN'] ) ) {
1379                         $sql = 'EXPLAIN ' . $sql;
1380                 }
1381
1382                 return $sql;
1383         }
1384
1385         /**
1386          * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
1387          * that a single row object is returned. If the query returns no rows,
1388          * false is returned.
1389          *
1390          * @param $table string|array Table name
1391          * @param $vars string|array Field names
1392          * @param $conds|array Conditions
1393          * @param $fname string Caller function name
1394          * @param $options string|array Query options
1395          * @param $join_conds array|string Join conditions
1396          *
1397          * @return ResultWrapper|bool
1398          */
1399         function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
1400                 $options = array(), $join_conds = array() )
1401         {
1402                 $options['LIMIT'] = 1;
1403                 $res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );
1404
1405                 if ( $res === false ) {
1406                         return false;
1407                 }
1408
1409                 if ( !$this->numRows( $res ) ) {
1410                         return false;
1411                 }
1412
1413                 $obj = $this->fetchObject( $res );
1414
1415                 return $obj;
1416         }
1417
1418         /**
1419          * Estimate rows in dataset.
1420          *
1421          * MySQL allows you to estimate the number of rows that would be returned
1422          * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
1423          * index cardinality statistics, and is notoriously inaccurate, especially
1424          * when large numbers of rows have recently been added or deleted.
1425          *
1426          * For DBMSs that don't support fast result size estimation, this function
1427          * will actually perform the SELECT COUNT(*).
1428          *
1429          * Takes the same arguments as DatabaseBase::select().
1430          *
1431          * @param $table String: table name
1432          * @param $vars Array: unused
1433          * @param $conds Array: filters on the table
1434          * @param $fname String: function name for profiling
1435          * @param $options Array: options for select
1436          * @return Integer: row count
1437          */
1438         public function estimateRowCount( $table, $vars = '*', $conds = '',
1439                 $fname = 'DatabaseBase::estimateRowCount', $options = array() )
1440         {
1441                 $rows = 0;
1442                 $res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );
1443
1444                 if ( $res ) {
1445                         $row = $this->fetchRow( $res );
1446                         $rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
1447                 }
1448
1449                 return $rows;
1450         }
1451
1452         /**
1453          * Removes most variables from an SQL query and replaces them with X or N for numbers.
1454          * It's only slightly flawed. Don't use for anything important.
1455          *
1456          * @param $sql String A SQL Query
1457          *
1458          * @return string
1459          */
1460         static function generalizeSQL( $sql ) {
1461                 # This does the same as the regexp below would do, but in such a way
1462                 # as to avoid crashing php on some large strings.
1463                 # $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);
1464
1465                 $sql = str_replace ( "\\\\", '', $sql );
1466                 $sql = str_replace ( "\\'", '', $sql );
1467                 $sql = str_replace ( "\\\"", '', $sql );
1468                 $sql = preg_replace ( "/'.*'/s", "'X'", $sql );
1469                 $sql = preg_replace ( '/".*"/s', "'X'", $sql );
1470
1471                 # All newlines, tabs, etc replaced by single space
1472                 $sql = preg_replace ( '/\s+/', ' ', $sql );
1473
1474                 # All numbers => N
1475                 $sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );
1476
1477                 return $sql;
1478         }
1479
1480         /**
1481          * Determines whether a field exists in a table
1482          *
1483          * @param $table String: table name
1484          * @param $field String: filed to check on that table
1485          * @param $fname String: calling function name (optional)
1486          * @return Boolean: whether $table has filed $field
1487          */
1488         function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
1489                 $info = $this->fieldInfo( $table, $field );
1490
1491                 return (bool)$info;
1492         }
1493
1494         /**
1495          * Determines whether an index exists
1496          * Usually throws a DBQueryError on failure
1497          * If errors are explicitly ignored, returns NULL on failure
1498          *
1499          * @param $table
1500          * @param $index
1501          * @param $fname string
1502          *
1503          * @return bool|null
1504          */
1505         function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
1506                 $info = $this->indexInfo( $table, $index, $fname );
1507                 if ( is_null( $info ) ) {
1508                         return null;
1509                 } else {
1510                         return $info !== false;
1511                 }
1512         }
1513
1514         /**
1515          * Query whether a given table exists
1516          *
1517          * @param $table string
1518          *
1519          * @return bool
1520          */
1521         function tableExists( $table ) {
1522                 $table = $this->tableName( $table );
1523                 $old = $this->ignoreErrors( true );
1524                 $res = $this->query( "SELECT 1 FROM $table LIMIT 1", __METHOD__ );
1525                 $this->ignoreErrors( $old );
1526
1527                 return (bool)$res;
1528         }
1529
1530         /**
1531          * mysql_field_type() wrapper
1532          */
1533         function fieldType( $res, $index ) {
1534                 if ( $res instanceof ResultWrapper ) {
1535                         $res = $res->result;
1536                 }
1537
1538                 return mysql_field_type( $res, $index );
1539         }
1540
1541         /**
1542          * Determines if a given index is unique
1543          *
1544          * @param $table string
1545          * @param $index string
1546          *
1547          * @return bool
1548          */
1549         function indexUnique( $table, $index ) {
1550                 $indexInfo = $this->indexInfo( $table, $index );
1551
1552                 if ( !$indexInfo ) {
1553                         return null;
1554                 }
1555
1556                 return !$indexInfo[0]->Non_unique;
1557         }
1558
1559         /**
1560          * Helper for DatabaseBase::insert().
1561          *
1562          * @param $options array
1563          * @return string
1564          */
1565         function makeInsertOptions( $options ) {
1566                 return implode( ' ', $options );
1567         }
1568
1569         /**
1570          * INSERT wrapper, inserts an array into a table.
1571          *
1572          * $a may be either:
1573          *
1574          *   - A single associative array. The array keys are the field names, and
1575          *     the values are the values to insert. The values are treated as data
1576          *     and will be quoted appropriately. If NULL is inserted, this will be
1577          *     converted to a database NULL.
1578          *   - An array with numeric keys, holding a list of associative arrays.
1579          *     This causes a multi-row INSERT on DBMSs that support it. The keys in
1580          *     each subarray must be identical to each other, and in the same order.
1581          *
1582          * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
1583          * returns success.
1584          *
1585          * $options is an array of options, with boolean options encoded as values
1586          * with numeric keys, in the same style as $options in
1587          * DatabaseBase::select(). Supported options are:
1588          *
1589          *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
1590          *     any rows which cause duplicate key errors are not inserted. It's
1591          *     possible to determine how many rows were successfully inserted using
1592          *     DatabaseBase::affectedRows().
1593          *
1594          * @param $table   String Table name. This will be passed through
1595          *                 DatabaseBase::tableName().
1596          * @param $a       Array of rows to insert
1597          * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
1598          * @param $options Array of options
1599          *
1600          * @return bool
1601          */
1602         function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
1603                 # No rows to insert, easy just return now
1604                 if ( !count( $a ) ) {
1605                         return true;
1606                 }
1607
1608                 $table = $this->tableName( $table );
1609
1610                 if ( !is_array( $options ) ) {
1611                         $options = array( $options );
1612                 }
1613
1614                 $options = $this->makeInsertOptions( $options );
1615
1616                 if ( isset( $a[0] ) && is_array( $a[0] ) ) {
1617                         $multi = true;
1618                         $keys = array_keys( $a[0] );
1619                 } else {
1620                         $multi = false;
1621                         $keys = array_keys( $a );
1622                 }
1623
1624                 $sql = 'INSERT ' . $options .
1625                         " INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1626
1627                 if ( $multi ) {
1628                         $first = true;
1629                         foreach ( $a as $row ) {
1630                                 if ( $first ) {
1631                                         $first = false;
1632                                 } else {
1633                                         $sql .= ',';
1634                                 }
1635                                 $sql .= '(' . $this->makeList( $row ) . ')';
1636                         }
1637                 } else {
1638                         $sql .= '(' . $this->makeList( $a ) . ')';
1639                 }
1640
1641                 return (bool)$this->query( $sql, $fname );
1642         }
1643
1644         /**
1645          * Make UPDATE options for the DatabaseBase::update function
1646          *
1647          * @param $options Array: The options passed to DatabaseBase::update
1648          * @return string
1649          */
1650         function makeUpdateOptions( $options ) {
1651                 if ( !is_array( $options ) ) {
1652                         $options = array( $options );
1653                 }
1654
1655                 $opts = array();
1656
1657                 if ( in_array( 'LOW_PRIORITY', $options ) ) {
1658                         $opts[] = $this->lowPriorityOption();
1659                 }
1660
1661                 if ( in_array( 'IGNORE', $options ) ) {
1662                         $opts[] = 'IGNORE';
1663                 }
1664
1665                 return implode( ' ', $opts );
1666         }
1667
1668         /**
1669          * UPDATE wrapper. Takes a condition array and a SET array.
1670          *
1671          * @param $table  String name of the table to UPDATE. This will be passed through
1672          *                DatabaseBase::tableName().
1673          *
1674          * @param $values Array:  An array of values to SET. For each array element,
1675          *                the key gives the field name, and the value gives the data
1676          *                to set that field to. The data will be quoted by
1677          *                DatabaseBase::addQuotes().
1678          *
1679          * @param $conds  Array:  An array of conditions (WHERE). See
1680          *                DatabaseBase::select() for the details of the format of
1681          *                condition arrays. Use '*' to update all rows.
1682          *
1683          * @param $fname  String: The function name of the caller (from __METHOD__),
1684          *                for logging and profiling.
1685          *
1686          * @param $options Array: An array of UPDATE options, can be:
1687          *                   - IGNORE: Ignore unique key conflicts
1688          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
1689          * @return Boolean
1690          */
1691         function update( $table, $values, $conds, $fname = 'DatabaseBase::update', $options = array() ) {
1692                 $table = $this->tableName( $table );
1693                 $opts = $this->makeUpdateOptions( $options );
1694                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1695
1696                 if ( $conds != '*' ) {
1697                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1698                 }
1699
1700                 return $this->query( $sql, $fname );
1701         }
1702
1703         /**
1704          * Makes an encoded list of strings from an array
1705          * @param $a Array containing the data
1706          * @param $mode int Constant
1707          *      - LIST_COMMA:          comma separated, no field names
1708          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
1709          *        the documentation for $conds in DatabaseBase::select().
1710          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
1711          *      - LIST_SET:            comma separated with field names, like a SET clause
1712          *      - LIST_NAMES:          comma separated field names
1713          *
1714          * In LIST_AND or LIST_OR modes, you can suffix a field with an exclamation
1715          * mark to generate a 'NOT IN' structure.
1716          *
1717          * Example:
1718          *  $db->makeList( array( 'field!' => array( 1,2,3 ) );
1719          *
1720          *  outputs:
1721          *    'field' NOT IN ('1', '2', '3' );
1722
1723          * @return string
1724          */
1725         function makeList( $a, $mode = LIST_COMMA ) {
1726                 if ( !is_array( $a ) ) {
1727                         throw new DBUnexpectedError( $this, 'DatabaseBase::makeList called with incorrect parameters' );
1728                 }
1729
1730                 $first = true;
1731                 $list = '';
1732
1733                 foreach ( $a as $field => $value ) {
1734                         if ( !$first ) {
1735                                 if ( $mode == LIST_AND ) {
1736                                         $list .= ' AND ';
1737                                 } elseif ( $mode == LIST_OR ) {
1738                                         $list .= ' OR ';
1739                                 } else {
1740                                         $list .= ',';
1741                                 }
1742                         } else {
1743                                 $first = false;
1744                         }
1745
1746                         // Support 'NOT IN' by suffixing fieldname with an exclamation mark
1747                         $not = false;
1748                         if( substr($field,-1) == '!' ) {
1749                                 $not = true;
1750                                 $field = substr($field, 0, -1 );
1751                         }
1752
1753                         if ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_numeric( $field ) ) {
1754                                 $list .= "($value)";
1755                         } elseif ( ( $mode == LIST_SET ) && is_numeric( $field ) ) {
1756                                 $list .= "$value";
1757                         } elseif ( ( $mode == LIST_AND || $mode == LIST_OR ) && is_array( $value ) ) {
1758                                 if ( count( $value ) == 0 ) {
1759                                         throw new MWException( __METHOD__ . ': empty input' );
1760                                 } elseif ( count( $value ) == 1 ) {
1761                                         // Special-case single values, as IN isn't terribly efficient
1762                                         // Don't necessarily assume the single key is 0; we don't
1763                                         // enforce linear numeric ordering on other arrays here.
1764                                         $value = array_values( $value );
1765
1766                                         $operator = $not ? ' != ' : ' = ';
1767                                         $list .= $field . $operator . $this->addQuotes( $value[0] );
1768                                 } else {
1769                                         $operator = $not ? ' NOT IN ' : ' IN ';
1770                                         $list .= $field . $operator . "(" . $this->makeList( $value ) . ")";
1771                                 }
1772                         } elseif ( $value === null ) {
1773                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
1774                                         $list .= "$field IS ";
1775                                         if ( $not ) {
1776                                                 $list .= "NOT ";
1777                                         }
1778                                 } elseif ( $mode == LIST_SET ) {
1779                                         $list .= "$field = ";
1780                                 }
1781                                 $list .= 'NULL';
1782                         } else {
1783                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
1784                                         $list .= "$field = ";
1785                                 }
1786                                 $list .= $mode == LIST_NAMES ? $value : $this->addQuotes( $value );
1787                         }
1788                 }
1789
1790                 return $list;
1791         }
1792
1793         /**
1794          * Build a partial where clause from a 2-d array such as used for LinkBatch.
1795          * The keys on each level may be either integers or strings.
1796          *
1797          * @param $data Array: organized as 2-d
1798          *              array(baseKeyVal => array(subKeyVal => <ignored>, ...), ...)
1799          * @param $baseKey String: field name to match the base-level keys to (eg 'pl_namespace')
1800          * @param $subKey String: field name to match the sub-level keys to (eg 'pl_title')
1801          * @return Mixed: string SQL fragment, or false if no items in array.
1802          */
1803         function makeWhereFrom2d( $data, $baseKey, $subKey ) {
1804                 $conds = array();
1805
1806                 foreach ( $data as $base => $sub ) {
1807                         if ( count( $sub ) ) {
1808                                 $conds[] = $this->makeList(
1809                                         array( $baseKey => $base, $subKey => array_keys( $sub ) ),
1810                                         LIST_AND );
1811                         }
1812                 }
1813
1814                 if ( $conds ) {
1815                         return $this->makeList( $conds, LIST_OR );
1816                 } else {
1817                         // Nothing to search for...
1818                         return false;
1819                 }
1820         }
1821
1822         /**
1823          * Build a partial where clause from a 3-d array
1824          * The keys on each level may be either integers or strings.
1825          *
1826          * @param $data Array: organized as 3-d array(baseKeyVal => array(middleKeyVal => array(subKeyVal => <ignored>, ...), ...), ...)
1827          * @param $baseKey String: field name to match the base-level keys to (eg 'gtl_to_prefix')
1828          * @param $middleKey String: field name to match the middle-level keys to (eg 'gtl_to_namespace')
1829          * @param $subKey String: field name to match the sub-level keys to (eg 'gtl_to_title')
1830          * @return Mixed: string SQL fragment, or false if no items in array.
1831          */
1832         function makeWhereFrom3d( $data, $baseKey, $middleKey, $subKey ) {
1833                 $conds = array();
1834                 foreach ( $data as $base => $subdata ) {
1835                         foreach ( $subdata as $middle => $sub ) {
1836                                 if ( count( $sub ) ) {
1837                                         $conds[] = $this->makeList(
1838                                                 array( $baseKey => $base,
1839                                                         $middleKey => $middle,
1840                                                         $subKey => array_keys( $sub ) ),
1841                                                 LIST_AND
1842                                         );
1843                                 }
1844                         }
1845                 }
1846
1847                 if ( $conds ) {
1848                         return $this->makeList( $conds, LIST_OR );
1849                 } else {
1850                         // Nothing to search for...
1851                         return false;
1852                 }
1853         }
1854
1855         /**
1856          * Bitwise operations
1857          */
1858
1859         /**
1860          * @param $field
1861          * @return string
1862          */
1863         function bitNot( $field ) {
1864                 return "(~$field)";
1865         }
1866
1867         /**
1868          * @param $fieldLeft
1869          * @param $fieldRight
1870          * @return string
1871          */
1872         function bitAnd( $fieldLeft, $fieldRight ) {
1873                 return "($fieldLeft & $fieldRight)";
1874         }
1875
1876         /**
1877          * @param  $fieldLeft
1878          * @param  $fieldRight
1879          * @return string
1880          */
1881         function bitOr( $fieldLeft, $fieldRight ) {
1882                 return "($fieldLeft | $fieldRight)";
1883         }
1884
1885         /**
1886          * Change the current database
1887          *
1888          * @todo Explain what exactly will fail if this is not overridden.
1889          *
1890          * @param $db
1891          *
1892          * @return bool Success or failure
1893          */
1894         function selectDB( $db ) {
1895                 # Stub.  Shouldn't cause serious problems if it's not overridden, but
1896                 # if your database engine supports a concept similar to MySQL's
1897                 # databases you may as well.
1898                 $this->mDBname = $db;
1899                 return true;
1900         }
1901
1902         /**
1903          * Get the current DB name
1904          */
1905         function getDBname() {
1906                 return $this->mDBname;
1907         }
1908
1909         /**
1910          * Get the server hostname or IP address
1911          */
1912         function getServer() {
1913                 return $this->mServer;
1914         }
1915
1916         /**
1917          * Format a table name ready for use in constructing an SQL query
1918          *
1919          * This does two important things: it quotes the table names to clean them up,
1920          * and it adds a table prefix if only given a table name with no quotes.
1921          *
1922          * All functions of this object which require a table name call this function
1923          * themselves. Pass the canonical name to such functions. This is only needed
1924          * when calling query() directly.
1925          *
1926          * @param $name String: database table name
1927          * @param $quoted Boolean: Automatically pass the table name through
1928          *          addIdentifierQuotes() so that it can be used in a query.
1929          * @return String: full database name
1930          */
1931         function tableName( $name, $quoted = true ) {
1932                 global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
1933                 # Skip the entire process when we have a string quoted on both ends.
1934                 # Note that we check the end so that we will still quote any use of
1935                 # use of `database`.table. But won't break things if someone wants
1936                 # to query a database table with a dot in the name.
1937                 if ( $this->isQuotedIdentifier( $name ) ) {
1938                         return $name;
1939                 }
1940
1941                 # Lets test for any bits of text that should never show up in a table
1942                 # name. Basically anything like JOIN or ON which are actually part of
1943                 # SQL queries, but may end up inside of the table value to combine
1944                 # sql. Such as how the API is doing.
1945                 # Note that we use a whitespace test rather than a \b test to avoid
1946                 # any remote case where a word like on may be inside of a table name
1947                 # surrounded by symbols which may be considered word breaks.
1948                 if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
1949                         return $name;
1950                 }
1951
1952                 # Split database and table into proper variables.
1953                 # We reverse the explode so that database.table and table both output
1954                 # the correct table.
1955                 $dbDetails = array_reverse( explode( '.', $name, 2 ) );
1956                 if ( isset( $dbDetails[1] ) ) {
1957                         list( $table, $database ) = $dbDetails;
1958                 } else {
1959                         list( $table ) = $dbDetails;
1960                 }
1961                 $prefix = $this->mTablePrefix; # Default prefix
1962
1963                 # A database name has been specified in input. We don't want any
1964                 # prefixes added.
1965                 if ( isset( $database ) ) {
1966                         $prefix = '';
1967                 }
1968
1969                 # Note that we use the long format because php will complain in in_array if
1970                 # the input is not an array, and will complain in is_array if it is not set.
1971                 if ( !isset( $database ) # Don't use shared database if pre selected.
1972                  && isset( $wgSharedDB ) # We have a shared database
1973                  && !$this->isQuotedIdentifier( $table ) # Paranoia check to prevent shared tables listing '`table`'
1974                  && isset( $wgSharedTables )
1975                  && is_array( $wgSharedTables )
1976                  && in_array( $table, $wgSharedTables ) ) { # A shared table is selected
1977                         $database = $wgSharedDB;
1978                         $prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
1979                 }
1980
1981                 # Quote the $database and $table and apply the prefix if not quoted.
1982                 if ( isset( $database ) ) {
1983                         $database = ( !$quoted || $this->isQuotedIdentifier( $database ) ? $database : $this->addIdentifierQuotes( $database ) );
1984                 }
1985
1986                 $table = "{$prefix}{$table}";
1987                 if ( $quoted && !$this->isQuotedIdentifier( $table ) ) {
1988                         $table = $this->addIdentifierQuotes( "{$table}" );
1989                 }
1990
1991                 # Merge our database and table into our final table name.
1992                 $tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );
1993
1994                 return $tableName;
1995         }
1996
1997         /**
1998          * Fetch a number of table names into an array
1999          * This is handy when you need to construct SQL for joins
2000          *
2001          * Example:
2002          * extract($dbr->tableNames('user','watchlist'));
2003          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2004          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2005          *
2006          * @return array
2007          */
2008         public function tableNames() {
2009                 $inArray = func_get_args();
2010                 $retVal = array();
2011
2012                 foreach ( $inArray as $name ) {
2013                         $retVal[$name] = $this->tableName( $name );
2014                 }
2015
2016                 return $retVal;
2017         }
2018
2019         /**
2020          * Fetch a number of table names into an zero-indexed numerical array
2021          * This is handy when you need to construct SQL for joins
2022          *
2023          * Example:
2024          * list( $user, $watchlist ) = $dbr->tableNamesN('user','watchlist');
2025          * $sql = "SELECT wl_namespace,wl_title FROM $watchlist,$user
2026          *         WHERE wl_user=user_id AND wl_user=$nameWithQuotes";
2027          *
2028          * @return array
2029          */
2030         public function tableNamesN() {
2031                 $inArray = func_get_args();
2032                 $retVal = array();
2033
2034                 foreach ( $inArray as $name ) {
2035                         $retVal[] = $this->tableName( $name );
2036                 }
2037
2038                 return $retVal;
2039         }
2040
2041         /**
2042          * Get an aliased table name
2043          * e.g. tableName AS newTableName
2044          *
2045          * @param $name string Table name, see tableName()
2046          * @param $alias string|bool Alias (optional)
2047          * @return string SQL name for aliased table. Will not alias a table to its own name
2048          */
2049         public function tableNameWithAlias( $name, $alias = false ) {
2050                 if ( !$alias || $alias == $name ) {
2051                         return $this->tableName( $name );
2052                 } else {
2053                         return $this->tableName( $name ) . ' ' . $this->addIdentifierQuotes( $alias );
2054                 }
2055         }
2056
2057         /**
2058          * Gets an array of aliased table names
2059          *
2060          * @param $tables array( [alias] => table )
2061          * @return array of strings, see tableNameWithAlias()
2062          */
2063         public function tableNamesWithAlias( $tables ) {
2064                 $retval = array();
2065                 foreach ( $tables as $alias => $table ) {
2066                         if ( is_numeric( $alias ) ) {
2067                                 $alias = $table;
2068                         }
2069                         $retval[] = $this->tableNameWithAlias( $table, $alias );
2070                 }
2071                 return $retval;
2072         }
2073
2074         /**
2075          * Get the aliased table name clause for a FROM clause
2076          * which might have a JOIN and/or USE INDEX clause
2077          *
2078          * @param $tables array ( [alias] => table )
2079          * @param $use_index array Same as for select()
2080          * @param $join_conds array Same as for select()
2081          * @return string
2082          */
2083         protected function tableNamesWithUseIndexOrJOIN(
2084                 $tables, $use_index = array(), $join_conds = array()
2085         ) {
2086                 $ret = array();
2087                 $retJOIN = array();
2088                 $use_index = (array)$use_index;
2089                 $join_conds = (array)$join_conds;
2090
2091                 foreach ( $tables as $alias => $table ) {
2092                         if ( !is_string( $alias ) ) {
2093                                 // No alias? Set it equal to the table name
2094                                 $alias = $table;
2095                         }
2096                         // Is there a JOIN clause for this table?
2097                         if ( isset( $join_conds[$alias] ) ) {
2098                                 list( $joinType, $conds ) = $join_conds[$alias];
2099                                 $tableClause = $joinType;
2100                                 $tableClause .= ' ' . $this->tableNameWithAlias( $table, $alias );
2101                                 if ( isset( $use_index[$alias] ) ) { // has USE INDEX?
2102                                         $use = $this->useIndexClause( implode( ',', (array)$use_index[$alias] ) );
2103                                         if ( $use != '' ) {
2104                                                 $tableClause .= ' ' . $use;
2105                                         }
2106                                 }
2107                                 $on = $this->makeList( (array)$conds, LIST_AND );
2108                                 if ( $on != '' ) {
2109                                         $tableClause .= ' ON (' . $on . ')';
2110                                 }
2111
2112                                 $retJOIN[] = $tableClause;
2113                         // Is there an INDEX clause for this table?
2114                         } elseif ( isset( $use_index[$alias] ) ) {
2115                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2116                                 $tableClause .= ' ' . $this->useIndexClause(
2117                                         implode( ',', (array)$use_index[$alias] ) );
2118
2119                                 $ret[] = $tableClause;
2120                         } else {
2121                                 $tableClause = $this->tableNameWithAlias( $table, $alias );
2122
2123                                 $ret[] = $tableClause;
2124                         }
2125                 }
2126
2127                 // We can't separate explicit JOIN clauses with ',', use ' ' for those
2128                 $straightJoins = !empty( $ret ) ? implode( ',', $ret ) : "";
2129                 $otherJoins = !empty( $retJOIN ) ? implode( ' ', $retJOIN ) : "";
2130
2131                 // Compile our final table clause
2132                 return implode( ' ', array( $straightJoins, $otherJoins ) );
2133         }
2134
2135         /**
2136          * Get the name of an index in a given table
2137          *
2138          * @param $index
2139          *
2140          * @return string
2141          */
2142         function indexName( $index ) {
2143                 // Backwards-compatibility hack
2144                 $renamed = array(
2145                         'ar_usertext_timestamp' => 'usertext_timestamp',
2146                         'un_user_id'            => 'user_id',
2147                         'un_user_ip'            => 'user_ip',
2148                 );
2149
2150                 if ( isset( $renamed[$index] ) ) {
2151                         return $renamed[$index];
2152                 } else {
2153                         return $index;
2154                 }
2155         }
2156
2157         /**
2158          * If it's a string, adds quotes and backslashes
2159          * Otherwise returns as-is
2160          *
2161          * @param $s string
2162          *
2163          * @return string
2164          */
2165         function addQuotes( $s ) {
2166                 if ( $s === null ) {
2167                         return 'NULL';
2168                 } else {
2169                         # This will also quote numeric values. This should be harmless,
2170                         # and protects against weird problems that occur when they really
2171                         # _are_ strings such as article titles and string->number->string
2172                         # conversion is not 1:1.
2173                         return "'" . $this->strencode( $s ) . "'";
2174                 }
2175         }
2176
2177         /**
2178          * Quotes an identifier using `backticks` or "double quotes" depending on the database type.
2179          * MySQL uses `backticks` while basically everything else uses double quotes.
2180          * Since MySQL is the odd one out here the double quotes are our generic
2181          * and we implement backticks in DatabaseMysql.
2182          *
2183          * @param $s string
2184          *
2185          * @return string
2186          */
2187         public function addIdentifierQuotes( $s ) {
2188                 return '"' . str_replace( '"', '""', $s ) . '"';
2189         }
2190
2191         /**
2192          * Returns if the given identifier looks quoted or not according to
2193          * the database convention for quoting identifiers .
2194          *
2195          * @param $name string
2196          *
2197          * @return boolean
2198          */
2199         public function isQuotedIdentifier( $name ) {
2200                 return $name[0] == '"' && substr( $name, -1, 1 ) == '"';
2201         }
2202
2203         /**
2204          * Backwards compatibility, identifier quoting originated in DatabasePostgres
2205          * which used quote_ident which does not follow our naming conventions
2206          * was renamed to addIdentifierQuotes.
2207          * @deprecated since 1.18 use addIdentifierQuotes
2208          *
2209          * @param $s string
2210          *
2211          * @return string
2212          */
2213         function quote_ident( $s ) {
2214                 wfDeprecated( __METHOD__ );
2215                 return $this->addIdentifierQuotes( $s );
2216         }
2217
2218         /**
2219          * Escape string for safe LIKE usage.
2220          * WARNING: you should almost never use this function directly,
2221          * instead use buildLike() that escapes everything automatically
2222          * @deprecated since 1.17, warnings in 1.17, removed in ???
2223          *
2224          * @param $s string
2225          *
2226          * @return string
2227          */
2228         public function escapeLike( $s ) {
2229                 wfDeprecated( __METHOD__ );
2230                 return $this->escapeLikeInternal( $s );
2231         }
2232
2233         /**
2234          * @param $s string
2235          * @return string
2236          */
2237         protected function escapeLikeInternal( $s ) {
2238                 $s = str_replace( '\\', '\\\\', $s );
2239                 $s = $this->strencode( $s );
2240                 $s = str_replace( array( '%', '_' ), array( '\%', '\_' ), $s );
2241
2242                 return $s;
2243         }
2244
2245         /**
2246          * LIKE statement wrapper, receives a variable-length argument list with parts of pattern to match
2247          * containing either string literals that will be escaped or tokens returned by anyChar() or anyString().
2248          * Alternatively, the function could be provided with an array of aforementioned parameters.
2249          *
2250          * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns a LIKE clause that searches
2251          * for subpages of 'My page title'.
2252          * Alternatively: $pattern = array( 'My_page_title/', $dbr->anyString() ); $query .= $dbr->buildLike( $pattern );
2253          *
2254          * @since 1.16
2255          * @return String: fully built LIKE statement
2256          */
2257         function buildLike() {
2258                 $params = func_get_args();
2259
2260                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
2261                         $params = $params[0];
2262                 }
2263
2264                 $s = '';
2265
2266                 foreach ( $params as $value ) {
2267                         if ( $value instanceof LikeMatch ) {
2268                                 $s .= $value->toString();
2269                         } else {
2270                                 $s .= $this->escapeLikeInternal( $value );
2271                         }
2272                 }
2273
2274                 return " LIKE '" . $s . "' ";
2275         }
2276
2277         /**
2278          * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
2279          *
2280          * @return LikeMatch
2281          */
2282         function anyChar() {
2283                 return new LikeMatch( '_' );
2284         }
2285
2286         /**
2287          * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
2288          *
2289          * @return LikeMatch
2290          */
2291         function anyString() {
2292                 return new LikeMatch( '%' );
2293         }
2294
2295         /**
2296          * Returns an appropriately quoted sequence value for inserting a new row.
2297          * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
2298          * subclass will return an integer, and save the value for insertId()
2299          */
2300         function nextSequenceValue( $seqName ) {
2301                 return null;
2302         }
2303
2304         /**
2305          * USE INDEX clause.  Unlikely to be useful for anything but MySQL.  This
2306          * is only needed because a) MySQL must be as efficient as possible due to
2307          * its use on Wikipedia, and b) MySQL 4.0 is kind of dumb sometimes about
2308          * which index to pick.  Anyway, other databases might have different
2309          * indexes on a given table.  So don't bother overriding this unless you're
2310          * MySQL.
2311          */
2312         function useIndexClause( $index ) {
2313                 return '';
2314         }
2315
2316         /**
2317          * REPLACE query wrapper.
2318          *
2319          * REPLACE is a very handy MySQL extension, which functions like an INSERT
2320          * except that when there is a duplicate key error, the old row is deleted
2321          * and the new row is inserted in its place.
2322          *
2323          * We simulate this with standard SQL with a DELETE followed by INSERT. To
2324          * perform the delete, we need to know what the unique indexes are so that
2325          * we know how to find the conflicting rows.
2326          *
2327          * It may be more efficient to leave off unique indexes which are unlikely
2328          * to collide. However if you do this, you run the risk of encountering
2329          * errors which wouldn't have occurred in MySQL.
2330          *
2331          * @param $table String: The table to replace the row(s) in.
2332          * @param $rows array Can be either a single row to insert, or multiple rows,
2333          *    in the same format as for DatabaseBase::insert()
2334          * @param $uniqueIndexes array is an array of indexes. Each element may be either
2335          *    a field name or an array of field names
2336          * @param $fname String: Calling function name (use __METHOD__) for logs/profiling
2337          */
2338         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseBase::replace' ) {
2339                 $quotedTable = $this->tableName( $table );
2340
2341                 if ( count( $rows ) == 0 ) {
2342                         return;
2343                 }
2344
2345                 # Single row case
2346                 if ( !is_array( reset( $rows ) ) ) {
2347                         $rows = array( $rows );
2348                 }
2349
2350                 foreach( $rows as $row ) {
2351                         # Delete rows which collide
2352                         if ( $uniqueIndexes ) {
2353                                 $sql = "DELETE FROM $quotedTable WHERE ";
2354                                 $first = true;
2355                                 foreach ( $uniqueIndexes as $index ) {
2356                                         if ( $first ) {
2357                                                 $first = false;
2358                                                 $sql .= '( ';
2359                                         } else {
2360                                                 $sql .= ' ) OR ( ';
2361                                         }
2362                                         if ( is_array( $index ) ) {
2363                                                 $first2 = true;
2364                                                 foreach ( $index as $col ) {
2365                                                         if ( $first2 ) {
2366                                                                 $first2 = false;
2367                                                         } else {
2368                                                                 $sql .= ' AND ';
2369                                                         }
2370                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
2371                                                 }
2372                                         } else {
2373                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
2374                                         }
2375                                 }
2376                                 $sql .= ' )';
2377                                 $this->query( $sql, $fname );
2378                         }
2379
2380                         # Now insert the row
2381                         $this->insert( $table, $row );
2382                 }
2383         }
2384
2385         /**
2386          * REPLACE query wrapper for MySQL and SQLite, which have a native REPLACE
2387          * statement.
2388          *
2389          * @param $table Table name
2390          * @param $rows Rows to insert
2391          * @param $fname Caller function name
2392          *
2393          * @return ResultWrapper
2394          */
2395         protected function nativeReplace( $table, $rows, $fname ) {
2396                 $table = $this->tableName( $table );
2397
2398                 # Single row case
2399                 if ( !is_array( reset( $rows ) ) ) {
2400                         $rows = array( $rows );
2401                 }
2402
2403                 $sql = "REPLACE INTO $table (" . implode( ',', array_keys( $rows[0] ) ) . ') VALUES ';
2404                 $first = true;
2405
2406                 foreach ( $rows as $row ) {
2407                         if ( $first ) {
2408                                 $first = false;
2409                         } else {
2410                                 $sql .= ',';
2411                         }
2412
2413                         $sql .= '(' . $this->makeList( $row ) . ')';
2414                 }
2415
2416                 return $this->query( $sql, $fname );
2417         }
2418
2419         /**
2420          * DELETE where the condition is a join.
2421          *
2422          * MySQL overrides this to use a multi-table DELETE syntax, in other databases
2423          * we use sub-selects
2424          *
2425          * For safety, an empty $conds will not delete everything. If you want to
2426          * delete all rows where the join condition matches, set $conds='*'.
2427          *
2428          * DO NOT put the join condition in $conds.
2429          *
2430          * @param $delTable   String: The table to delete from.
2431          * @param $joinTable  String: The other table.
2432          * @param $delVar     String: The variable to join on, in the first table.
2433          * @param $joinVar    String: The variable to join on, in the second table.
2434          * @param $conds      Array: Condition array of field names mapped to variables,
2435          *                    ANDed together in the WHERE clause
2436          * @param $fname      String: Calling function name (use __METHOD__) for
2437          *                    logs/profiling
2438          */
2439         function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
2440                 $fname = 'DatabaseBase::deleteJoin' )
2441         {
2442                 if ( !$conds ) {
2443                         throw new DBUnexpectedError( $this,
2444                                 'DatabaseBase::deleteJoin() called with empty $conds' );
2445                 }
2446
2447                 $delTable = $this->tableName( $delTable );
2448                 $joinTable = $this->tableName( $joinTable );
2449                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
2450                 if ( $conds != '*' ) {
2451                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
2452                 }
2453                 $sql .= ')';
2454
2455                 $this->query( $sql, $fname );
2456         }
2457
2458         /**
2459          * Returns the size of a text field, or -1 for "unlimited"
2460          *
2461          * @param $table string
2462          * @param $field string
2463          *
2464          * @return int
2465          */
2466         function textFieldSize( $table, $field ) {
2467                 $table = $this->tableName( $table );
2468                 $sql = "SHOW COLUMNS FROM $table LIKE \"$field\";";
2469                 $res = $this->query( $sql, 'DatabaseBase::textFieldSize' );
2470                 $row = $this->fetchObject( $res );
2471
2472                 $m = array();
2473
2474                 if ( preg_match( '/\((.*)\)/', $row->Type, $m ) ) {
2475                         $size = $m[1];
2476                 } else {
2477                         $size = -1;
2478                 }
2479
2480                 return $size;
2481         }
2482
2483         /**
2484          * A string to insert into queries to show that they're low-priority, like
2485          * MySQL's LOW_PRIORITY.  If no such feature exists, return an empty
2486          * string and nothing bad should happen.
2487          *
2488          * @return string Returns the text of the low priority option if it is
2489          *   supported, or a blank string otherwise
2490          */
2491         function lowPriorityOption() {
2492                 return '';
2493         }
2494
2495         /**
2496          * DELETE query wrapper.
2497          *
2498          * @param $table Array Table name
2499          * @param $conds String|Array of conditions. See $conds in DatabaseBase::select() for
2500          *               the format. Use $conds == "*" to delete all rows
2501          * @param $fname String name of the calling function
2502          *
2503          * @return bool
2504          */
2505         function delete( $table, $conds, $fname = 'DatabaseBase::delete' ) {
2506                 if ( !$conds ) {
2507                         throw new DBUnexpectedError( $this, 'DatabaseBase::delete() called with no conditions' );
2508                 }
2509
2510                 $table = $this->tableName( $table );
2511                 $sql = "DELETE FROM $table";
2512
2513                 if ( $conds != '*' ) {
2514                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2515                 }
2516
2517                 return $this->query( $sql, $fname );
2518         }
2519
2520         /**
2521          * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
2522          * into another table.
2523          *
2524          * @param $destTable string The table name to insert into
2525          * @param $srcTable string|array May be either a table name, or an array of table names
2526          *    to include in a join.
2527          *
2528          * @param $varMap array must be an associative array of the form
2529          *    array( 'dest1' => 'source1', ...). Source items may be literals
2530          *    rather than field names, but strings should be quoted with
2531          *    DatabaseBase::addQuotes()
2532          *
2533          * @param $conds array Condition array. See $conds in DatabaseBase::select() for
2534          *    the details of the format of condition arrays. May be "*" to copy the
2535          *    whole table.
2536          *
2537          * @param $fname string The function name of the caller, from __METHOD__
2538          *
2539          * @param $insertOptions array Options for the INSERT part of the query, see
2540          *    DatabaseBase::insert() for details.
2541          * @param $selectOptions array Options for the SELECT part of the query, see
2542          *    DatabaseBase::select() for details.
2543          *
2544          * @return ResultWrapper
2545          */
2546         function insertSelect( $destTable, $srcTable, $varMap, $conds,
2547                 $fname = 'DatabaseBase::insertSelect',
2548                 $insertOptions = array(), $selectOptions = array() )
2549         {
2550                 $destTable = $this->tableName( $destTable );
2551
2552                 if ( is_array( $insertOptions ) ) {
2553                         $insertOptions = implode( ' ', $insertOptions );
2554                 }
2555
2556                 if ( !is_array( $selectOptions ) ) {
2557                         $selectOptions = array( $selectOptions );
2558                 }
2559
2560                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
2561
2562                 if ( is_array( $srcTable ) ) {
2563                         $srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
2564                 } else {
2565                         $srcTable = $this->tableName( $srcTable );
2566                 }
2567
2568                 $sql = "INSERT $insertOptions INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
2569                         " SELECT $startOpts " . implode( ',', $varMap ) .
2570                         " FROM $srcTable $useIndex ";
2571
2572                 if ( $conds != '*' ) {
2573                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
2574                 }
2575
2576                 $sql .= " $tailOpts";
2577
2578                 return $this->query( $sql, $fname );
2579         }
2580
2581         /**
2582          * Construct a LIMIT query with optional offset.  This is used for query
2583          * pages.  The SQL should be adjusted so that only the first $limit rows
2584          * are returned.  If $offset is provided as well, then the first $offset
2585          * rows should be discarded, and the next $limit rows should be returned.
2586          * If the result of the query is not ordered, then the rows to be returned
2587          * are theoretically arbitrary.
2588          *
2589          * $sql is expected to be a SELECT, if that makes a difference.  For
2590          * UPDATE, limitResultForUpdate should be used.
2591          *
2592          * The version provided by default works in MySQL and SQLite.  It will very
2593          * likely need to be overridden for most other DBMSes.
2594          *
2595          * @param $sql String SQL query we will append the limit too
2596          * @param $limit Integer the SQL limit
2597          * @param $offset Integer|false the SQL offset (default false)
2598          *
2599          * @return string
2600          */
2601         function limitResult( $sql, $limit, $offset = false ) {
2602                 if ( !is_numeric( $limit ) ) {
2603                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
2604                 }
2605
2606                 return "$sql LIMIT "
2607                                 . ( ( is_numeric( $offset ) && $offset != 0 ) ? "{$offset}," : "" )
2608                                 . "{$limit} ";
2609         }
2610
2611         /**
2612          * @param $sql
2613          * @param $num
2614          * @return string
2615          */
2616         function limitResultForUpdate( $sql, $num ) {
2617                 return $this->limitResult( $sql, $num, 0 );
2618         }
2619
2620         /**
2621          * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
2622          * within the UNION construct.
2623          * @return Boolean
2624          */
2625         function unionSupportsOrderAndLimit() {
2626                 return true; // True for almost every DB supported
2627         }
2628
2629         /**
2630          * Construct a UNION query
2631          * This is used for providing overload point for other DB abstractions
2632          * not compatible with the MySQL syntax.
2633          * @param $sqls Array: SQL statements to combine
2634          * @param $all Boolean: use UNION ALL
2635          * @return String: SQL fragment
2636          */
2637         function unionQueries( $sqls, $all ) {
2638                 $glue = $all ? ') UNION ALL (' : ') UNION (';
2639                 return '(' . implode( $glue, $sqls ) . ')';
2640         }
2641
2642         /**
2643          * Returns an SQL expression for a simple conditional.  This doesn't need
2644          * to be overridden unless CASE isn't supported in your DBMS.
2645          *
2646          * @param $cond String: SQL expression which will result in a boolean value
2647          * @param $trueVal String: SQL expression to return if true
2648          * @param $falseVal String: SQL expression to return if false
2649          * @return String: SQL fragment
2650          */
2651         function conditional( $cond, $trueVal, $falseVal ) {
2652                 return " (CASE WHEN $cond THEN $trueVal ELSE $falseVal END) ";
2653         }
2654
2655         /**
2656          * Returns a comand for str_replace function in SQL query.
2657          * Uses REPLACE() in MySQL
2658          *
2659          * @param $orig String: column to modify
2660          * @param $old String: column to seek
2661          * @param $new String: column to replace with
2662          *
2663          * @return string
2664          */
2665         function strreplace( $orig, $old, $new ) {
2666                 return "REPLACE({$orig}, {$old}, {$new})";
2667         }
2668
2669         /**
2670          * Determines if the last failure was due to a deadlock
2671          * STUB
2672          *
2673          * @return bool
2674          */
2675         function wasDeadlock() {
2676                 return false;
2677         }
2678
2679         /**
2680          * Determines if the last query error was something that should be dealt
2681          * with by pinging the connection and reissuing the query.
2682          * STUB
2683          *
2684          * @return bool
2685          */
2686         function wasErrorReissuable() {
2687                 return false;
2688         }
2689
2690         /**
2691          * Determines if the last failure was due to the database being read-only.
2692          * STUB
2693          *
2694          * @return bool
2695          */
2696         function wasReadOnlyError() {
2697                 return false;
2698         }
2699
2700         /**
2701          * Perform a deadlock-prone transaction.
2702          *
2703          * This function invokes a callback function to perform a set of write
2704          * queries. If a deadlock occurs during the processing, the transaction
2705          * will be rolled back and the callback function will be called again.
2706          *
2707          * Usage:
2708          *   $dbw->deadlockLoop( callback, ... );
2709          *
2710          * Extra arguments are passed through to the specified callback function.
2711          *
2712          * Returns whatever the callback function returned on its successful,
2713          * iteration, or false on error, for example if the retry limit was
2714          * reached.
2715          *
2716          * @return bool
2717          */
2718         function deadlockLoop() {
2719                 $myFname = 'DatabaseBase::deadlockLoop';
2720
2721                 $this->begin();
2722                 $args = func_get_args();
2723                 $function = array_shift( $args );
2724                 $oldIgnore = $this->ignoreErrors( true );
2725                 $tries = DEADLOCK_TRIES;
2726
2727                 if ( is_array( $function ) ) {
2728                         $fname = $function[0];
2729                 } else {
2730                         $fname = $function;
2731                 }
2732
2733                 do {
2734                         $retVal = call_user_func_array( $function, $args );
2735                         $error = $this->lastError();
2736                         $errno = $this->lastErrno();
2737                         $sql = $this->lastQuery();
2738
2739                         if ( $errno ) {
2740                                 if ( $this->wasDeadlock() ) {
2741                                         # Retry
2742                                         usleep( mt_rand( DEADLOCK_DELAY_MIN, DEADLOCK_DELAY_MAX ) );
2743                                 } else {
2744                                         $this->reportQueryError( $error, $errno, $sql, $fname );
2745                                 }
2746                         }
2747                 } while ( $this->wasDeadlock() && --$tries > 0 );
2748
2749                 $this->ignoreErrors( $oldIgnore );
2750
2751                 if ( $tries <= 0 ) {
2752                         $this->rollback( $myFname );
2753                         $this->reportQueryError( $error, $errno, $sql, $fname );
2754                         return false;
2755                 } else {
2756                         $this->commit( $myFname );
2757                         return $retVal;
2758                 }
2759         }
2760
2761         /**
2762          * Wait for the slave to catch up to a given master position.
2763          *
2764          * @param $pos DBMasterPos object
2765          * @param $timeout Integer: the maximum number of seconds to wait for
2766          *   synchronisation
2767          *
2768          * @return An integer: zero if the slave was past that position already,
2769          *   greater than zero if we waited for some period of time, less than
2770          *   zero if we timed out.
2771          */
2772         function masterPosWait( DBMasterPos $pos, $timeout ) {
2773                 $fname = 'DatabaseBase::masterPosWait';
2774                 wfProfileIn( $fname );
2775
2776                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2777                         $wait = intval( ( $pos->pos - microtime( true ) + $this->mFakeSlaveLag ) * 1e6 );
2778
2779                         if ( $wait > $timeout * 1e6 ) {
2780                                 wfDebug( "Fake slave timed out waiting for $pos ($wait us)\n" );
2781                                 wfProfileOut( $fname );
2782                                 return -1;
2783                         } elseif ( $wait > 0 ) {
2784                                 wfDebug( "Fake slave waiting $wait us\n" );
2785                                 usleep( $wait );
2786                                 wfProfileOut( $fname );
2787                                 return 1;
2788                         } else {
2789                                 wfDebug( "Fake slave up to date ($wait us)\n" );
2790                                 wfProfileOut( $fname );
2791                                 return 0;
2792                         }
2793                 }
2794
2795                 wfProfileOut( $fname );
2796
2797                 # Real waits are implemented in the subclass.
2798                 return 0;
2799         }
2800
2801         /**
2802          * Get the replication position of this slave
2803          *
2804          * @return DBMasterPos, or false if this is not a slave.
2805          */
2806         function getSlavePos() {
2807                 if ( !is_null( $this->mFakeSlaveLag ) ) {
2808                         $pos = new MySQLMasterPos( 'fake', microtime( true ) - $this->mFakeSlaveLag );
2809                         wfDebug( __METHOD__ . ": fake slave pos = $pos\n" );
2810                         return $pos;
2811                 } else {
2812                         # Stub
2813                         return false;
2814                 }
2815         }
2816
2817         /**
2818          * Get the position of this master
2819          *
2820          * @return DBMasterPos, or false if this is not a master
2821          */
2822         function getMasterPos() {
2823                 if ( $this->mFakeMaster ) {
2824                         return new MySQLMasterPos( 'fake', microtime( true ) );
2825                 } else {
2826                         return false;
2827                 }
2828         }
2829
2830         /**
2831          * Begin a transaction, committing any previously open transaction
2832          *
2833          * @param $fname string
2834          */
2835         function begin( $fname = 'DatabaseBase::begin' ) {
2836                 $this->query( 'BEGIN', $fname );
2837                 $this->mTrxLevel = 1;
2838         }
2839
2840         /**
2841          * End a transaction
2842          *
2843          * @param $fname string
2844          */
2845         function commit( $fname = 'DatabaseBase::commit' ) {
2846                 if ( $this->mTrxLevel ) {
2847                         $this->query( 'COMMIT', $fname );
2848                         $this->mTrxLevel = 0;
2849                 }
2850         }
2851
2852         /**
2853          * Rollback a transaction.
2854          * No-op on non-transactional databases.
2855          *
2856          * @param $fname string
2857          */
2858         function rollback( $fname = 'DatabaseBase::rollback' ) {
2859                 if ( $this->mTrxLevel ) {
2860                         $this->query( 'ROLLBACK', $fname, true );
2861                         $this->mTrxLevel = 0;
2862                 }
2863         }
2864
2865         /**
2866          * Creates a new table with structure copied from existing table
2867          * Note that unlike most database abstraction functions, this function does not
2868          * automatically append database prefix, because it works at a lower
2869          * abstraction level.
2870          * The table names passed to this function shall not be quoted (this
2871          * function calls addIdentifierQuotes when needed).
2872          *
2873          * @param $oldName String: name of table whose structure should be copied
2874          * @param $newName String: name of table to be created
2875          * @param $temporary Boolean: whether the new table should be temporary
2876          * @param $fname String: calling function name
2877          * @return Boolean: true if operation was successful
2878          */
2879         function duplicateTableStructure( $oldName, $newName, $temporary = false,
2880                 $fname = 'DatabaseBase::duplicateTableStructure' )
2881         {
2882                 throw new MWException(
2883                         'DatabaseBase::duplicateTableStructure is not implemented in descendant class' );
2884         }
2885
2886         /**
2887          * List all tables on the database
2888          *
2889          * @param $prefix Only show tables with this prefix, e.g. mw_
2890          * @param $fname String: calling function name
2891          */
2892         function listTables( $prefix = null, $fname = 'DatabaseBase::listTables' ) {
2893                 throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
2894         }
2895
2896         /**
2897          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2898          * to the format used for inserting into timestamp fields in this DBMS.
2899          *
2900          * The result is unquoted, and needs to be passed through addQuotes()
2901          * before it can be included in raw SQL.
2902          *
2903          * @param $ts string|int
2904          *
2905          * @return string
2906          */
2907         function timestamp( $ts = 0 ) {
2908                 return wfTimestamp( TS_MW, $ts );
2909         }
2910
2911         /**
2912          * Convert a timestamp in one of the formats accepted by wfTimestamp()
2913          * to the format used for inserting into timestamp fields in this DBMS. If
2914          * NULL is input, it is passed through, allowing NULL values to be inserted
2915          * into timestamp fields.
2916          *
2917          * The result is unquoted, and needs to be passed through addQuotes()
2918          * before it can be included in raw SQL.
2919          *
2920          * @param $ts string|int
2921          *
2922          * @return string
2923          */
2924         function timestampOrNull( $ts = null ) {
2925                 if ( is_null( $ts ) ) {
2926                         return null;
2927                 } else {
2928                         return $this->timestamp( $ts );
2929                 }
2930         }
2931
2932         /**
2933          * Take the result from a query, and wrap it in a ResultWrapper if
2934          * necessary. Boolean values are passed through as is, to indicate success
2935          * of write queries or failure.
2936          *
2937          * Once upon a time, DatabaseBase::query() returned a bare MySQL result
2938          * resource, and it was necessary to call this function to convert it to
2939          * a wrapper. Nowadays, raw database objects are never exposed to external
2940          * callers, so this is unnecessary in external code. For compatibility with
2941          * old code, ResultWrapper objects are passed through unaltered.
2942          *
2943          * @param $result bool|ResultWrapper
2944          *
2945          * @param bool|ResultWrapper
2946          */
2947         function resultObject( $result ) {
2948                 if ( empty( $result ) ) {
2949                         return false;
2950                 } elseif ( $result instanceof ResultWrapper ) {
2951                         return $result;
2952                 } elseif ( $result === true ) {
2953                         // Successful write query
2954                         return $result;
2955                 } else {
2956                         return new ResultWrapper( $this, $result );
2957                 }
2958         }
2959
2960         /**
2961          * Return aggregated value alias
2962          *
2963          * @param $valuedata
2964          * @param $valuename string
2965          *
2966          * @return string
2967          */
2968         function aggregateValue ( $valuedata, $valuename = 'value' ) {
2969                 return $valuename;
2970         }
2971
2972         /**
2973          * Ping the server and try to reconnect if it there is no connection
2974          *
2975          * @return bool Success or failure
2976          */
2977         function ping() {
2978                 # Stub.  Not essential to override.
2979                 return true;
2980         }
2981
2982         /**
2983          * Get slave lag.
2984          * Currently supported only by MySQL
2985          * @return Database replication lag in seconds
2986          */
2987         function getLag() {
2988                 return intval( $this->mFakeSlaveLag );
2989         }
2990
2991         /**
2992          * Return the maximum number of items allowed in a list, or 0 for unlimited.
2993          *
2994          * @return int
2995          */
2996         function maxListLen() {
2997                 return 0;
2998         }
2999
3000         /**
3001          * Some DBMSs have a special format for inserting into blob fields, they
3002          * don't allow simple quoted strings to be inserted. To insert into such
3003          * a field, pass the data through this function before passing it to
3004          * DatabaseBase::insert().
3005          */
3006         function encodeBlob( $b ) {
3007                 return $b;
3008         }
3009
3010         /**
3011          * Some DBMSs return a special placeholder object representing blob fields
3012          * in result objects. Pass the object through this function to return the
3013          * original string.
3014          */
3015         function decodeBlob( $b ) {
3016                 return $b;
3017         }
3018
3019         /**
3020          * Override database's default connection timeout.  May be useful for very
3021          * long batch queries such as full-wiki dumps, where a single query reads
3022          * out over hours or days.  May or may not be necessary for non-MySQL
3023          * databases.  For most purposes, leaving it as a no-op should be fine.
3024          *
3025          * @param $timeout Integer in seconds
3026          */
3027         public function setTimeout( $timeout ) {}
3028
3029         /**
3030          * Read and execute SQL commands from a file.
3031          *
3032          * Returns true on success, error string or exception on failure (depending
3033          * on object's error ignore settings).
3034          *
3035          * @param $filename String: File name to open
3036          * @param $lineCallback Callback: Optional function called before reading each line
3037          * @param $resultCallback Callback: Optional function called for each MySQL result
3038          * @param $fname String: Calling function name or false if name should be
3039          *      generated dynamically using $filename
3040          */
3041         function sourceFile( $filename, $lineCallback = false, $resultCallback = false, $fname = false ) {
3042                 wfSuppressWarnings();
3043                 $fp = fopen( $filename, 'r' );
3044                 wfRestoreWarnings();
3045
3046                 if ( false === $fp ) {
3047                         throw new MWException( "Could not open \"{$filename}\".\n" );
3048                 }
3049
3050                 if ( !$fname ) {
3051                         $fname = __METHOD__ . "( $filename )";
3052                 }
3053
3054                 try {
3055                         $error = $this->sourceStream( $fp, $lineCallback, $resultCallback, $fname );
3056                 }
3057                 catch ( MWException $e ) {
3058                         fclose( $fp );
3059                         throw $e;
3060                 }
3061
3062                 fclose( $fp );
3063
3064                 return $error;
3065         }
3066
3067         /**
3068          * Get the full path of a patch file. Originally based on archive()
3069          * from updaters.inc. Keep in mind this always returns a patch, as
3070          * it fails back to MySQL if no DB-specific patch can be found
3071          *
3072          * @param $patch String The name of the patch, like patch-something.sql
3073          * @return String Full path to patch file
3074          */
3075         public function patchPath( $patch ) {
3076                 global $IP;
3077
3078                 $dbType = $this->getType();
3079                 if ( file_exists( "$IP/maintenance/$dbType/archives/$patch" ) ) {
3080                         return "$IP/maintenance/$dbType/archives/$patch";
3081                 } else {
3082                         return "$IP/maintenance/archives/$patch";
3083                 }
3084         }
3085
3086         /**
3087          * Set variables to be used in sourceFile/sourceStream, in preference to the
3088          * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
3089          * all. If it's set to false, $GLOBALS will be used.
3090          *
3091          * @param $vars False, or array mapping variable name to value.
3092          */
3093         function setSchemaVars( $vars ) {
3094                 $this->mSchemaVars = $vars;
3095         }
3096
3097         /**
3098          * Read and execute commands from an open file handle.
3099          *
3100          * Returns true on success, error string or exception on failure (depending
3101          * on object's error ignore settings).
3102          *
3103          * @param $fp Resource: File handle
3104          * @param $lineCallback Callback: Optional function called before reading each line
3105          * @param $resultCallback Callback: Optional function called for each MySQL result
3106          * @param $fname String: Calling function name
3107          */
3108         function sourceStream( $fp, $lineCallback = false, $resultCallback = false,
3109                 $fname = 'DatabaseBase::sourceStream' )
3110         {
3111                 $cmd = "";
3112                 $done = false;
3113                 $dollarquote = false;
3114
3115                 while ( ! feof( $fp ) ) {
3116                         if ( $lineCallback ) {
3117                                 call_user_func( $lineCallback );
3118                         }
3119
3120                         $line = trim( fgets( $fp ) );
3121                         $sl = strlen( $line ) - 1;
3122
3123                         if ( $sl < 0 ) {
3124                                 continue;
3125                         }
3126
3127                         if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
3128                                 continue;
3129                         }
3130
3131                         # # Allow dollar quoting for function declarations
3132                         if ( substr( $line, 0, 4 ) == '$mw$' ) {
3133                                 if ( $dollarquote ) {
3134                                         $dollarquote = false;
3135                                         $done = true;
3136                                 }
3137                                 else {
3138                                         $dollarquote = true;
3139                                 }
3140                         }
3141                         elseif ( !$dollarquote ) {
3142                                 if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
3143                                         $done = true;
3144                                         $line = substr( $line, 0, $sl );
3145                                 }
3146                         }
3147
3148                         if ( $cmd != '' ) {
3149                                 $cmd .= ' ';
3150                         }
3151
3152                         $cmd .= "$line\n";
3153
3154                         if ( $done ) {
3155                                 $cmd = str_replace( ';;', ";", $cmd );
3156                                 $cmd = $this->replaceVars( $cmd );
3157                                 $res = $this->query( $cmd, $fname );
3158
3159                                 if ( $resultCallback ) {
3160                                         call_user_func( $resultCallback, $res, $this );
3161                                 }
3162
3163                                 if ( false === $res ) {
3164                                         $err = $this->lastError();
3165                                         return "Query \"{$cmd}\" failed with error code \"$err\".\n";
3166                                 }
3167
3168                                 $cmd = '';
3169                                 $done = false;
3170                         }
3171                 }
3172
3173                 return true;
3174         }
3175
3176         /**
3177          * Database independent variable replacement. Replaces a set of variables
3178          * in an SQL statement with their contents as given by $this->getSchemaVars().
3179          *
3180          * Supports '{$var}' `{$var}` and / *$var* / (without the spaces) style variables.
3181          *
3182          * - '{$var}' should be used for text and is passed through the database's
3183          *   addQuotes method.
3184          * - `{$var}` should be used for identifiers (eg: table and database names),
3185          *   it is passed through the database's addIdentifierQuotes method which
3186          *   can be overridden if the database uses something other than backticks.
3187          * - / *$var* / is just encoded, besides traditional table prefix and
3188          *   table options its use should be avoided.
3189          *
3190          * @param $ins String: SQL statement to replace variables in
3191          * @return String The new SQL statement with variables replaced
3192          */
3193         protected function replaceSchemaVars( $ins ) {
3194                 $vars = $this->getSchemaVars();
3195                 foreach ( $vars as $var => $value ) {
3196                         // replace '{$var}'
3197                         $ins = str_replace( '\'{$' . $var . '}\'', $this->addQuotes( $value ), $ins );
3198                         // replace `{$var}`
3199                         $ins = str_replace( '`{$' . $var . '}`', $this->addIdentifierQuotes( $value ), $ins );
3200                         // replace /*$var*/
3201                         $ins = str_replace( '/*$' . $var . '*/', $this->strencode( $value ) , $ins );
3202                 }
3203                 return $ins;
3204         }
3205
3206         /**
3207          * Replace variables in sourced SQL
3208          *
3209          * @param $ins string
3210          *
3211          * @return string
3212          */
3213         protected function replaceVars( $ins ) {
3214                 $ins = $this->replaceSchemaVars( $ins );
3215
3216                 // Table prefixes
3217                 $ins = preg_replace_callback( '!/\*(?:\$wgDBprefix|_)\*/([a-zA-Z_0-9]*)!',
3218                         array( $this, 'tableNameCallback' ), $ins );
3219
3220                 // Index names
3221                 $ins = preg_replace_callback( '!/\*i\*/([a-zA-Z_0-9]*)!',
3222                         array( $this, 'indexNameCallback' ), $ins );
3223
3224                 return $ins;
3225         }
3226
3227         /**
3228          * Get schema variables. If none have been set via setSchemaVars(), then
3229          * use some defaults from the current object.
3230          */
3231         protected function getSchemaVars() {
3232                 if ( $this->mSchemaVars ) {
3233                         return $this->mSchemaVars;
3234                 } else {
3235                         return $this->getDefaultSchemaVars();
3236                 }
3237         }
3238
3239         /**
3240          * Get schema variables to use if none have been set via setSchemaVars().
3241          *
3242          * Override this in derived classes to provide variables for tables.sql
3243          * and SQL patch files.
3244          *
3245          * @return array
3246          */
3247         protected function getDefaultSchemaVars() {
3248                 return array();
3249         }
3250
3251         /**
3252          * Table name callback
3253          *
3254          * @param $matches array
3255          *
3256          * @return string
3257          */
3258         protected function tableNameCallback( $matches ) {
3259                 return $this->tableName( $matches[1] );
3260         }
3261
3262         /**
3263          * Index name callback
3264          *
3265          * @param $matches array
3266          *
3267          * @return string
3268          */
3269         protected function indexNameCallback( $matches ) {
3270                 return $this->indexName( $matches[1] );
3271         }
3272
3273         /**
3274          * Build a concatenation list to feed into a SQL query
3275          * @param $stringList Array: list of raw SQL expressions; caller is responsible for any quoting
3276          * @return String
3277          */
3278         function buildConcat( $stringList ) {
3279                 return 'CONCAT(' . implode( ',', $stringList ) . ')';
3280         }
3281
3282         /**
3283          * Acquire a named lock
3284          *
3285          * Abstracted from Filestore::lock() so child classes can implement for
3286          * their own needs.
3287          *
3288          * @param $lockName String: name of lock to aquire
3289          * @param $method String: name of method calling us
3290          * @param $timeout Integer: timeout
3291          * @return Boolean
3292          */
3293         public function lock( $lockName, $method, $timeout = 5 ) {
3294                 return true;
3295         }
3296
3297         /**
3298          * Release a lock.
3299          *
3300          * @param $lockName String: Name of lock to release
3301          * @param $method String: Name of method calling us
3302          *
3303          * @return Returns 1 if the lock was released, 0 if the lock was not established
3304          * by this thread (in which case the lock is not released), and NULL if the named
3305          * lock did not exist
3306          */
3307         public function unlock( $lockName, $method ) {
3308                 return true;
3309         }
3310
3311         /**
3312          * Lock specific tables
3313          *
3314          * @param $read Array of tables to lock for read access
3315          * @param $write Array of tables to lock for write access
3316          * @param $method String name of caller
3317          * @param $lowPriority bool Whether to indicate writes to be LOW PRIORITY
3318          *
3319          * @return bool
3320          */
3321         public function lockTables( $read, $write, $method, $lowPriority = true ) {
3322                 return true;
3323         }
3324
3325         /**
3326          * Unlock specific tables
3327          *
3328          * @param $method String the caller
3329          *
3330          * @return bool
3331          */
3332         public function unlockTables( $method ) {
3333                 return true;
3334         }
3335
3336         /**
3337          * Delete a table
3338          * @param $tableName string
3339          * @param $fName string
3340          * @return bool|ResultWrapper
3341          */
3342         public function dropTable( $tableName, $fName = 'DatabaseBase::dropTable' ) {
3343                 if( !$this->tableExists( $tableName ) ) {
3344                         return false;
3345                 }
3346                 $sql = "DROP TABLE " . $this->tableName( $tableName );
3347                 if( $this->cascadingDeletes() ) {
3348                         $sql .= " CASCADE";
3349                 }
3350                 return $this->query( $sql, $fName );
3351         }
3352
3353         /**
3354          * Get search engine class. All subclasses of this need to implement this
3355          * if they wish to use searching.
3356          *
3357          * @return String
3358          */
3359         public function getSearchEngine() {
3360                 return 'SearchEngineDummy';
3361         }
3362
3363         /**
3364          * Find out when 'infinity' is. Most DBMSes support this. This is a special
3365          * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
3366          * because "i" sorts after all numbers.
3367          *
3368          * @return String
3369          */
3370         public function getInfinity() {
3371                 return 'infinity';
3372         }
3373
3374         /**
3375          * Encode an expiry time
3376          *
3377          * @param $expiry String: timestamp for expiry, or the 'infinity' string
3378          * @return String
3379          */
3380         public function encodeExpiry( $expiry ) {
3381                 if ( $expiry == '' || $expiry == $this->getInfinity() ) {
3382                         return $this->getInfinity();
3383                 } else {
3384                         return $this->timestamp( $expiry );
3385                 }
3386         }
3387
3388         /**
3389          * Allow or deny "big selects" for this session only. This is done by setting
3390          * the sql_big_selects session variable.
3391          *
3392          * This is a MySQL-specific feature.
3393          *
3394          * @param $value Mixed: true for allow, false for deny, or "default" to
3395          *   restore the initial value
3396          */
3397         public function setBigSelects( $value = true ) {
3398                 // no-op
3399         }
3400 }