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