includes/libs/rdbms/database/DatabaseMysqlBase.php

   1 <?php
   2 /**
   3  * This is the MySQL database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 namespace Wikimedia\Rdbms;
  24
  25 use DateTime;
  26 use DateTimeZone;
  27 use Wikimedia;
  28 use InvalidArgumentException;
  29 use Exception;
  30 use stdClass;
  31
  32 /**
  33  * Database abstraction object for MySQL.
  34  * Defines methods independent on used MySQL extension.
  35  *
  36  * @ingroup Database
  37  * @since 1.22
  38  * @see Database
  39  */
  40 abstract class DatabaseMysqlBase extends Database {
  41         /** @var MysqlMasterPos */
  42         protected $lastKnownReplicaPos;
  43         /** @var string Method to detect replica DB lag */
  44         protected $lagDetectionMethod;
  45         /** @var array Method to detect replica DB lag */
  46         protected $lagDetectionOptions = [];
  47         /** @var bool bool Whether to use GTID methods */
  48         protected $useGTIDs = false;
  49         /** @var string|null */
  50         protected $sslKeyPath;
  51         /** @var string|null */
  52         protected $sslCertPath;
  53         /** @var string|null */
  54         protected $sslCAFile;
  55         /** @var string|null */
  56         protected $sslCAPath;
  57         /** @var string[]|null */
  58         protected $sslCiphers;
  59         /** @var string sql_mode value to send on connection */
  60         protected $sqlMode;
  61         /** @var bool Use experimental UTF-8 transmission encoding */
  62         protected $utf8Mode;
  63         /** @var bool|null */
  64         protected $defaultBigSelects = null;
  65
  66         /** @var string|null */
  67         private $serverVersion = null;
  68         /** @var bool|null */
  69         private $insertSelectIsSafe = null;
  70
  71         /**
  72          * Additional $params include:
  73          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  74          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  75          *       and uses UTC timestamps in the heartbeat.ts column.
  76          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  77          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  78          *       the default behavior. Normally, the heartbeat row with the server
  79          *       ID of this server's master will be used. Set the "conds" field to
  80          *       override the query conditions, e.g. ['shard' => 's1'].
  81          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  82          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  83          *   - sslKeyPath : path to key file [default: null]
  84          *   - sslCertPath : path to certificate file [default: null]
  85          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  86          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  87          *   - sslCiphers : array list of allowable ciphers [default: null]
  88          * @param array $params
  89          */
  90         function __construct( array $params ) {
  91                 $this->lagDetectionMethod = isset( $params['lagDetectionMethod'] )
  92                         ? $params['lagDetectionMethod']
  93                         : 'Seconds_Behind_Master';
  94                 $this->lagDetectionOptions = isset( $params['lagDetectionOptions'] )
  95                         ? $params['lagDetectionOptions']
  96                         : [];
  97                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
  98                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
  99                         $var = "ssl{$name}";
 100                         if ( isset( $params[$var] ) ) {
 101                                 $this->$var = $params[$var];
 102                         }
 103                 }
 104                 $this->sqlMode = isset( $params['sqlMode'] ) ? $params['sqlMode'] : '';
 105                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 106                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 107                         ? (bool)$params['insertSelectIsSafe'] : null;
 108
 109                 parent::__construct( $params );
 110         }
 111
 112         /**
 113          * @return string
 114          */
 115         public function getType() {
 116                 return 'mysql';
 117         }
 118
 119         /**
 120          * @param string $server
 121          * @param string $user
 122          * @param string $password
 123          * @param string $dbName
 124          * @throws Exception|DBConnectionError
 125          * @return bool
 126          */
 127         public function open( $server, $user, $password, $dbName ) {
 128                 # Close/unset connection handle
 129                 $this->close();
 130
 131                 $this->server = $server;
 132                 $this->user = $user;
 133                 $this->password = $password;
 134                 $this->dbName = $dbName;
 135
 136                 $this->installErrorHandler();
 137                 try {
 138                         $this->conn = $this->mysqlConnect( $this->server );
 139                 } catch ( Exception $ex ) {
 140                         $this->restoreErrorHandler();
 141                         throw $ex;
 142                 }
 143                 $error = $this->restoreErrorHandler();
 144
 145                 # Always log connection errors
 146                 if ( !$this->conn ) {
 147                         if ( !$error ) {
 148                                 $error = $this->lastError();
 149                         }
 150                         $this->connLogger->error(
 151                                 "Error connecting to {db_server}: {error}",
 152                                 $this->getLogContext( [
 153                                         'method' => __METHOD__,
 154                                         'error' => $error,
 155                                 ] )
 156                         );
 157                         $this->connLogger->debug( "DB connection error\n" .
 158                                 "Server: $server, User: $user, Password: " .
 159                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 160
 161                         $this->reportConnectionError( $error );
 162                 }
 163
 164                 if ( strlen( $dbName ) ) {
 165                         Wikimedia\suppressWarnings();
 166                         $success = $this->selectDB( $dbName );
 167                         Wikimedia\restoreWarnings();
 168                         if ( !$success ) {
 169                                 $this->queryLogger->error(
 170                                         "Error selecting database {db_name} on server {db_server}",
 171                                         $this->getLogContext( [
 172                                                 'method' => __METHOD__,
 173                                         ] )
 174                                 );
 175                                 $this->queryLogger->debug(
 176                                         "Error selecting database $dbName on server {$this->server}" );
 177
 178                                 $this->reportConnectionError( "Error selecting database $dbName" );
 179                         }
 180                 }
 181
 182                 // Tell the server what we're communicating with
 183                 if ( !$this->connectInitCharset() ) {
 184                         $this->reportConnectionError( "Error setting character set" );
 185                 }
 186
 187                 // Abstract over any insane MySQL defaults
 188                 $set = [ 'group_concat_max_len = 262144' ];
 189                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 190                 if ( is_string( $this->sqlMode ) ) {
 191                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 192                 }
 193                 // Set any custom settings defined by site config
 194                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 195                 foreach ( $this->sessionVars as $var => $val ) {
 196                         // Escape strings but not numbers to avoid MySQL complaining
 197                         if ( !is_int( $val ) && !is_float( $val ) ) {
 198                                 $val = $this->addQuotes( $val );
 199                         }
 200                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 201                 }
 202
 203                 if ( $set ) {
 204                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 205                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 206                         if ( !$success ) {
 207                                 $this->queryLogger->error(
 208                                         'Error setting MySQL variables on server {db_server} (check $wgSQLMode)',
 209                                         $this->getLogContext( [
 210                                                 'method' => __METHOD__,
 211                                         ] )
 212                                 );
 213                                 $this->reportConnectionError(
 214                                         'Error setting MySQL variables on server {db_server} (check $wgSQLMode)' );
 215                         }
 216                 }
 217
 218                 $this->opened = true;
 219
 220                 return true;
 221         }
 222
 223         /**
 224          * Set the character set information right after connection
 225          * @return bool
 226          */
 227         protected function connectInitCharset() {
 228                 if ( $this->utf8Mode ) {
 229                         // Tell the server we're communicating with it in UTF-8.
 230                         // This may engage various charset conversions.
 231                         return $this->mysqlSetCharset( 'utf8' );
 232                 } else {
 233                         return $this->mysqlSetCharset( 'binary' );
 234                 }
 235         }
 236
 237         /**
 238          * Open a connection to a MySQL server
 239          *
 240          * @param string $realServer
 241          * @return mixed Raw connection
 242          * @throws DBConnectionError
 243          */
 244         abstract protected function mysqlConnect( $realServer );
 245
 246         /**
 247          * Set the character set of the MySQL link
 248          *
 249          * @param string $charset
 250          * @return bool
 251          */
 252         abstract protected function mysqlSetCharset( $charset );
 253
 254         /**
 255          * @param ResultWrapper|resource $res
 256          * @throws DBUnexpectedError
 257          */
 258         public function freeResult( $res ) {
 259                 if ( $res instanceof ResultWrapper ) {
 260                         $res = $res->result;
 261                 }
 262                 Wikimedia\suppressWarnings();
 263                 $ok = $this->mysqlFreeResult( $res );
 264                 Wikimedia\restoreWarnings();
 265                 if ( !$ok ) {
 266                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 267                 }
 268         }
 269
 270         /**
 271          * Free result memory
 272          *
 273          * @param resource $res Raw result
 274          * @return bool
 275          */
 276         abstract protected function mysqlFreeResult( $res );
 277
 278         /**
 279          * @param ResultWrapper|resource $res
 280          * @return stdClass|bool
 281          * @throws DBUnexpectedError
 282          */
 283         public function fetchObject( $res ) {
 284                 if ( $res instanceof ResultWrapper ) {
 285                         $res = $res->result;
 286                 }
 287                 Wikimedia\suppressWarnings();
 288                 $row = $this->mysqlFetchObject( $res );
 289                 Wikimedia\restoreWarnings();
 290
 291                 $errno = $this->lastErrno();
 292                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 293                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 294                 // these are the only errors mysql_fetch_object can cause.
 295                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 296                 if ( $errno == 2000 || $errno == 2013 ) {
 297                         throw new DBUnexpectedError(
 298                                 $this,
 299                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 300                         );
 301                 }
 302
 303                 return $row;
 304         }
 305
 306         /**
 307          * Fetch a result row as an object
 308          *
 309          * @param resource $res Raw result
 310          * @return stdClass
 311          */
 312         abstract protected function mysqlFetchObject( $res );
 313
 314         /**
 315          * @param ResultWrapper|resource $res
 316          * @return array|bool
 317          * @throws DBUnexpectedError
 318          */
 319         public function fetchRow( $res ) {
 320                 if ( $res instanceof ResultWrapper ) {
 321                         $res = $res->result;
 322                 }
 323                 Wikimedia\suppressWarnings();
 324                 $row = $this->mysqlFetchArray( $res );
 325                 Wikimedia\restoreWarnings();
 326
 327                 $errno = $this->lastErrno();
 328                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 329                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 330                 // these are the only errors mysql_fetch_array can cause.
 331                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 332                 if ( $errno == 2000 || $errno == 2013 ) {
 333                         throw new DBUnexpectedError(
 334                                 $this,
 335                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 336                         );
 337                 }
 338
 339                 return $row;
 340         }
 341
 342         /**
 343          * Fetch a result row as an associative and numeric array
 344          *
 345          * @param resource $res Raw result
 346          * @return array
 347          */
 348         abstract protected function mysqlFetchArray( $res );
 349
 350         /**
 351          * @throws DBUnexpectedError
 352          * @param ResultWrapper|resource $res
 353          * @return int
 354          */
 355         function numRows( $res ) {
 356                 if ( $res instanceof ResultWrapper ) {
 357                         $res = $res->result;
 358                 }
 359                 Wikimedia\suppressWarnings();
 360                 $n = $this->mysqlNumRows( $res );
 361                 Wikimedia\restoreWarnings();
 362
 363                 // Unfortunately, mysql_num_rows does not reset the last errno.
 364                 // We are not checking for any errors here, since
 365                 // these are no errors mysql_num_rows can cause.
 366                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 367                 // See https://phabricator.wikimedia.org/T44430
 368                 return $n;
 369         }
 370
 371         /**
 372          * Get number of rows in result
 373          *
 374          * @param resource $res Raw result
 375          * @return int
 376          */
 377         abstract protected function mysqlNumRows( $res );
 378
 379         /**
 380          * @param ResultWrapper|resource $res
 381          * @return int
 382          */
 383         public function numFields( $res ) {
 384                 if ( $res instanceof ResultWrapper ) {
 385                         $res = $res->result;
 386                 }
 387
 388                 return $this->mysqlNumFields( $res );
 389         }
 390
 391         /**
 392          * Get number of fields in result
 393          *
 394          * @param resource $res Raw result
 395          * @return int
 396          */
 397         abstract protected function mysqlNumFields( $res );
 398
 399         /**
 400          * @param ResultWrapper|resource $res
 401          * @param int $n
 402          * @return string
 403          */
 404         public function fieldName( $res, $n ) {
 405                 if ( $res instanceof ResultWrapper ) {
 406                         $res = $res->result;
 407                 }
 408
 409                 return $this->mysqlFieldName( $res, $n );
 410         }
 411
 412         /**
 413          * Get the name of the specified field in a result
 414          *
 415          * @param ResultWrapper|resource $res
 416          * @param int $n
 417          * @return string
 418          */
 419         abstract protected function mysqlFieldName( $res, $n );
 420
 421         /**
 422          * mysql_field_type() wrapper
 423          * @param ResultWrapper|resource $res
 424          * @param int $n
 425          * @return string
 426          */
 427         public function fieldType( $res, $n ) {
 428                 if ( $res instanceof ResultWrapper ) {
 429                         $res = $res->result;
 430                 }
 431
 432                 return $this->mysqlFieldType( $res, $n );
 433         }
 434
 435         /**
 436          * Get the type of the specified field in a result
 437          *
 438          * @param ResultWrapper|resource $res
 439          * @param int $n
 440          * @return string
 441          */
 442         abstract protected function mysqlFieldType( $res, $n );
 443
 444         /**
 445          * @param ResultWrapper|resource $res
 446          * @param int $row
 447          * @return bool
 448          */
 449         public function dataSeek( $res, $row ) {
 450                 if ( $res instanceof ResultWrapper ) {
 451                         $res = $res->result;
 452                 }
 453
 454                 return $this->mysqlDataSeek( $res, $row );
 455         }
 456
 457         /**
 458          * Move internal result pointer
 459          *
 460          * @param ResultWrapper|resource $res
 461          * @param int $row
 462          * @return bool
 463          */
 464         abstract protected function mysqlDataSeek( $res, $row );
 465
 466         /**
 467          * @return string
 468          */
 469         public function lastError() {
 470                 if ( $this->conn ) {
 471                         # Even if it's non-zero, it can still be invalid
 472                         Wikimedia\suppressWarnings();
 473                         $error = $this->mysqlError( $this->conn );
 474                         if ( !$error ) {
 475                                 $error = $this->mysqlError();
 476                         }
 477                         Wikimedia\restoreWarnings();
 478                 } else {
 479                         $error = $this->mysqlError();
 480                 }
 481                 if ( $error ) {
 482                         $error .= ' (' . $this->server . ')';
 483                 }
 484
 485                 return $error;
 486         }
 487
 488         /**
 489          * Returns the text of the error message from previous MySQL operation
 490          *
 491          * @param resource $conn Raw connection
 492          * @return string
 493          */
 494         abstract protected function mysqlError( $conn = null );
 495
 496         protected function wasQueryTimeout( $error, $errno ) {
 497                 return $errno == 2062;
 498         }
 499
 500         /**
 501          * @param string $table
 502          * @param array $uniqueIndexes
 503          * @param array $rows
 504          * @param string $fname
 505          * @return ResultWrapper
 506          */
 507         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 508                 return $this->nativeReplace( $table, $rows, $fname );
 509         }
 510
 511         protected function nativeInsertSelect(
 512                 $destTable, $srcTable, $varMap, $conds,
 513                 $fname = __METHOD__, $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 514         ) {
 515                 if ( $this->insertSelectIsSafe === null ) {
 516                         // In MySQL, an INSERT SELECT is only replication safe with row-based
 517                         // replication or if innodb_autoinc_lock_mode is 0. When those
 518                         // conditions aren't met, use non-native mode.
 519                         // While we could try to determine if the insert is safe anyway by
 520                         // checking if the target table has an auto-increment column that
 521                         // isn't set in $varMap, that seems unlikely to be worth the extra
 522                         // complexity.
 523                         $row = $this->selectRow(
 524                                 false,
 525                                 [
 526                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 527                                         'binlog_format' => '@@binlog_format',
 528                                 ],
 529                                 [],
 530                                 __METHOD__
 531                         );
 532                         $this->insertSelectIsSafe = $row->binlog_format === 'ROW' ||
 533                                 (int)$row->innodb_autoinc_lock_mode === 0;
 534                 }
 535
 536                 if ( !$this->insertSelectIsSafe ) {
 537                         return $this->nonNativeInsertSelect(
 538                                 $destTable,
 539                                 $srcTable,
 540                                 $varMap,
 541                                 $conds,
 542                                 $fname,
 543                                 $insertOptions,
 544                                 $selectOptions,
 545                                 $selectJoinConds
 546                         );
 547                 } else {
 548                         return parent::nativeInsertSelect(
 549                                 $destTable,
 550                                 $srcTable,
 551                                 $varMap,
 552                                 $conds,
 553                                 $fname,
 554                                 $insertOptions,
 555                                 $selectOptions,
 556                                 $selectJoinConds
 557                         );
 558                 }
 559         }
 560
 561         /**
 562          * Estimate rows in dataset
 563          * Returns estimated count, based on EXPLAIN output
 564          * Takes same arguments as Database::select()
 565          *
 566          * @param string|array $table
 567          * @param string|array $vars
 568          * @param string|array $conds
 569          * @param string $fname
 570          * @param string|array $options
 571          * @return bool|int
 572          */
 573         public function estimateRowCount( $table, $vars = '*', $conds = '',
 574                 $fname = __METHOD__, $options = []
 575         ) {
 576                 $options['EXPLAIN'] = true;
 577                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 578                 if ( $res === false ) {
 579                         return false;
 580                 }
 581                 if ( !$this->numRows( $res ) ) {
 582                         return 0;
 583                 }
 584
 585                 $rows = 1;
 586                 foreach ( $res as $plan ) {
 587                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 588                 }
 589
 590                 return (int)$rows;
 591         }
 592
 593         public function tableExists( $table, $fname = __METHOD__ ) {
 594                 // Split database and table into proper variables as Database::tableName() returns
 595                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 596                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 597                 $tableName = "{$prefix}{$table}";
 598
 599                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 600                         return true; // already known to exist and won't show in SHOW TABLES anyway
 601                 }
 602
 603                 // We can't use buildLike() here, because it specifies an escape character
 604                 // other than the backslash, which is the only one supported by SHOW TABLES
 605                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 606
 607                 // If the database has been specified (such as for shared tables), use "FROM"
 608                 if ( $database !== '' ) {
 609                         $encDatabase = $this->addIdentifierQuotes( $database );
 610                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 611                 } else {
 612                         $query = "SHOW TABLES LIKE '$encLike'";
 613                 }
 614
 615                 return $this->query( $query, $fname )->numRows() > 0;
 616         }
 617
 618         /**
 619          * @param string $table
 620          * @param string $field
 621          * @return bool|MySQLField
 622          */
 623         public function fieldInfo( $table, $field ) {
 624                 $table = $this->tableName( $table );
 625                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 626                 if ( !$res ) {
 627                         return false;
 628                 }
 629                 $n = $this->mysqlNumFields( $res->result );
 630                 for ( $i = 0; $i < $n; $i++ ) {
 631                         $meta = $this->mysqlFetchField( $res->result, $i );
 632                         if ( $field == $meta->name ) {
 633                                 return new MySQLField( $meta );
 634                         }
 635                 }
 636
 637                 return false;
 638         }
 639
 640         /**
 641          * Get column information from a result
 642          *
 643          * @param resource $res Raw result
 644          * @param int $n
 645          * @return stdClass
 646          */
 647         abstract protected function mysqlFetchField( $res, $n );
 648
 649         /**
 650          * Get information about an index into an object
 651          * Returns false if the index does not exist
 652          *
 653          * @param string $table
 654          * @param string $index
 655          * @param string $fname
 656          * @return bool|array|null False or null on failure
 657          */
 658         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 659                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 660                 # SHOW INDEX should work for 3.x and up:
 661                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 662                 $table = $this->tableName( $table );
 663                 $index = $this->indexName( $index );
 664
 665                 $sql = 'SHOW INDEX FROM ' . $table;
 666                 $res = $this->query( $sql, $fname );
 667
 668                 if ( !$res ) {
 669                         return null;
 670                 }
 671
 672                 $result = [];
 673
 674                 foreach ( $res as $row ) {
 675                         if ( $row->Key_name == $index ) {
 676                                 $result[] = $row;
 677                         }
 678                 }
 679
 680                 return empty( $result ) ? false : $result;
 681         }
 682
 683         /**
 684          * @param string $s
 685          * @return string
 686          */
 687         public function strencode( $s ) {
 688                 return $this->mysqlRealEscapeString( $s );
 689         }
 690
 691         /**
 692          * @param string $s
 693          * @return mixed
 694          */
 695         abstract protected function mysqlRealEscapeString( $s );
 696
 697         public function addQuotes( $s ) {
 698                 if ( is_bool( $s ) ) {
 699                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 700                         // When searching for an int in a string column, the strings are cast to int, which
 701                         // means false would match any string not starting with a number.
 702                         $s = (string)(int)$s;
 703                 }
 704                 return parent::addQuotes( $s );
 705         }
 706
 707         /**
 708          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 709          *
 710          * @param string $s
 711          * @return string
 712          */
 713         public function addIdentifierQuotes( $s ) {
 714                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 715                 // Remove NUL bytes and escape backticks by doubling
 716                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 717         }
 718
 719         /**
 720          * @param string $name
 721          * @return bool
 722          */
 723         public function isQuotedIdentifier( $name ) {
 724                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 725         }
 726
 727         public function getLag() {
 728                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 729                         return $this->getLagFromPtHeartbeat();
 730                 } else {
 731                         return $this->getLagFromSlaveStatus();
 732                 }
 733         }
 734
 735         /**
 736          * @return string
 737          */
 738         protected function getLagDetectionMethod() {
 739                 return $this->lagDetectionMethod;
 740         }
 741
 742         /**
 743          * @return bool|int
 744          */
 745         protected function getLagFromSlaveStatus() {
 746                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 747                 $row = $res ? $res->fetchObject() : false;
 748                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 749                         return intval( $row->Seconds_Behind_Master );
 750                 }
 751
 752                 return false;
 753         }
 754
 755         /**
 756          * @return bool|float
 757          */
 758         protected function getLagFromPtHeartbeat() {
 759                 $options = $this->lagDetectionOptions;
 760
 761                 if ( isset( $options['conds'] ) ) {
 762                         // Best method for multi-DC setups: use logical channel names
 763                         $data = $this->getHeartbeatData( $options['conds'] );
 764                 } else {
 765                         // Standard method: use master server ID (works with stock pt-heartbeat)
 766                         $masterInfo = $this->getMasterServerInfo();
 767                         if ( !$masterInfo ) {
 768                                 $this->queryLogger->error(
 769                                         "Unable to query master of {db_server} for server ID",
 770                                         $this->getLogContext( [
 771                                                 'method' => __METHOD__
 772                                         ] )
 773                                 );
 774
 775                                 return false; // could not get master server ID
 776                         }
 777
 778                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 779                         $data = $this->getHeartbeatData( $conds );
 780                 }
 781
 782                 list( $time, $nowUnix ) = $data;
 783                 if ( $time !== null ) {
 784                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 785                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 786                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 787
 788                         return max( $nowUnix - $timeUnix, 0.0 );
 789                 }
 790
 791                 $this->queryLogger->error(
 792                         "Unable to find pt-heartbeat row for {db_server}",
 793                         $this->getLogContext( [
 794                                 'method' => __METHOD__
 795                         ] )
 796                 );
 797
 798                 return false;
 799         }
 800
 801         protected function getMasterServerInfo() {
 802                 $cache = $this->srvCache;
 803                 $key = $cache->makeGlobalKey(
 804                         'mysql',
 805                         'master-info',
 806                         // Using one key for all cluster replica DBs is preferable
 807                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 808                 );
 809
 810                 return $cache->getWithSetCallback(
 811                         $key,
 812                         $cache::TTL_INDEFINITE,
 813                         function () use ( $cache, $key ) {
 814                                 // Get and leave a lock key in place for a short period
 815                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 816                                         return false; // avoid master connection spike slams
 817                                 }
 818
 819                                 $conn = $this->getLazyMasterHandle();
 820                                 if ( !$conn ) {
 821                                         return false; // something is misconfigured
 822                                 }
 823
 824                                 // Connect to and query the master; catch errors to avoid outages
 825                                 try {
 826                                         $res = $conn->query( 'SELECT @@server_id AS id', __METHOD__ );
 827                                         $row = $res ? $res->fetchObject() : false;
 828                                         $id = $row ? (int)$row->id : 0;
 829                                 } catch ( DBError $e ) {
 830                                         $id = 0;
 831                                 }
 832
 833                                 // Cache the ID if it was retrieved
 834                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 835                         }
 836                 );
 837         }
 838
 839         /**
 840          * @param array $conds WHERE clause conditions to find a row
 841          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 842          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 843          */
 844         protected function getHeartbeatData( array $conds ) {
 845                 // Query time and trip time are not counted
 846                 $nowUnix = microtime( true );
 847                 // Do not bother starting implicit transactions here
 848                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 849                 try {
 850                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 851                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 852                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 853                         // percision field is not supported in MySQL <= 5.5.
 854                         $res = $this->query(
 855                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1"
 856                         );
 857                         $row = $res ? $res->fetchObject() : false;
 858                 } finally {
 859                         $this->restoreFlags();
 860                 }
 861
 862                 return [ $row ? $row->ts : null, $nowUnix ];
 863         }
 864
 865         protected function getApproximateLagStatus() {
 866                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 867                         // Disable caching since this is fast enough and we don't wan't
 868                         // to be *too* pessimistic by having both the cache TTL and the
 869                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 870                         return parent::getApproximateLagStatus();
 871                 }
 872
 873                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 874                 $approxLag = $this->srvCache->get( $key );
 875                 if ( !$approxLag ) {
 876                         $approxLag = parent::getApproximateLagStatus();
 877                         $this->srvCache->set( $key, $approxLag, 1 );
 878                 }
 879
 880                 return $approxLag;
 881         }
 882
 883         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 884                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 885                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 886                 }
 887
 888                 if ( $this->getLBInfo( 'is static' ) === true ) {
 889                         return 0; // this is a copy of a read-only dataset with no master DB
 890                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 891                         return 0; // already reached this point for sure
 892                 }
 893
 894                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 895                 if ( $pos->getGTIDs() ) {
 896                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 897                         $rpos = $this->getReplicaPos();
 898                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 899                         if ( !$gtidsWait ) {
 900                                 return -1; // $pos is from the wrong cluster?
 901                         }
 902                         // Wait on the GTID set (MariaDB only)
 903                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 904                         $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 905                 } else {
 906                         // Wait on the binlog coordinates
 907                         $encFile = $this->addQuotes( $pos->getLogFile() );
 908                         $encPos = intval( $pos->pos[1] );
 909                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 910                 }
 911
 912                 $row = $res ? $this->fetchRow( $res ) : false;
 913                 if ( !$row ) {
 914                         throw new DBExpectedError( $this,
 915                                 "MASTER_POS_WAIT() or MASTER_GTID_WAIT() failed: {$this->lastError()}" );
 916                 }
 917
 918                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 919                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 920                 if ( $status === null ) {
 921                         if ( !$pos->getGTIDs() ) {
 922                                 // T126436: jobs programmed to wait on master positions might be referencing
 923                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 924                                 // Try to detect this case and treat the replica DB as having reached the given
 925                                 // position (any master switchover already requires that the new master be caught
 926                                 // up before the switch).
 927                                 $replicationPos = $this->getReplicaPos();
 928                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 929                                         $this->lastKnownReplicaPos = $replicationPos;
 930                                         $status = 0;
 931                                 }
 932                         }
 933                 } elseif ( $status >= 0 ) {
 934                         // Remember that this position was reached to save queries next time
 935                         $this->lastKnownReplicaPos = $pos;
 936                 }
 937
 938                 return $status;
 939         }
 940
 941         /**
 942          * Get the position of the master from SHOW SLAVE STATUS
 943          *
 944          * @return MySQLMasterPos|bool
 945          */
 946         public function getReplicaPos() {
 947                 $now = microtime( true );
 948
 949                 if ( $this->useGTIDs ) {
 950                         $res = $this->query( "SELECT @@global.gtid_slave_pos AS Value", __METHOD__ );
 951                         $gtidRow = $this->fetchObject( $res );
 952                         if ( $gtidRow && strlen( $gtidRow->Value ) ) {
 953                                 return new MySQLMasterPos( $gtidRow->Value, $now );
 954                         }
 955                 }
 956
 957                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 958                 $row = $this->fetchObject( $res );
 959                 if ( $row && strlen( $row->Relay_Master_Log_File ) ) {
 960                         return new MySQLMasterPos(
 961                                 "{$row->Relay_Master_Log_File}/{$row->Exec_Master_Log_Pos}",
 962                                 $now
 963                         );
 964                 }
 965
 966                 return false;
 967         }
 968
 969         /**
 970          * Get the position of the master from SHOW MASTER STATUS
 971          *
 972          * @return MySQLMasterPos|bool
 973          */
 974         public function getMasterPos() {
 975                 $now = microtime( true );
 976
 977                 if ( $this->useGTIDs ) {
 978                         $res = $this->query( "SELECT @@global.gtid_binlog_pos AS Value", __METHOD__ );
 979                         $gtidRow = $this->fetchObject( $res );
 980                         if ( $gtidRow && strlen( $gtidRow->Value ) ) {
 981                                 return new MySQLMasterPos( $gtidRow->Value, $now );
 982                         }
 983                 }
 984
 985                 $res = $this->query( 'SHOW MASTER STATUS', __METHOD__ );
 986                 $row = $this->fetchObject( $res );
 987                 if ( $row && strlen( $row->File ) ) {
 988                         return new MySQLMasterPos( "{$row->File}/{$row->Position}", $now );
 989                 }
 990
 991                 return false;
 992         }
 993
 994         public function serverIsReadOnly() {
 995                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
 996                 $row = $this->fetchObject( $res );
 997
 998                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
 999         }
1000
1001         /**
1002          * @param string $index
1003          * @return string
1004          */
1005         function useIndexClause( $index ) {
1006                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1007         }
1008
1009         /**
1010          * @param string $index
1011          * @return string
1012          */
1013         function ignoreIndexClause( $index ) {
1014                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1015         }
1016
1017         /**
1018          * @return string
1019          */
1020         function lowPriorityOption() {
1021                 return 'LOW_PRIORITY';
1022         }
1023
1024         /**
1025          * @return string
1026          */
1027         public function getSoftwareLink() {
1028                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1029                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1030                 // in libmysql/libmysql.c).
1031                 $version = $this->getServerVersion();
1032                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1033                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1034                 }
1035
1036                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1037                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1038                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1039                 return '[{{int:version-db-mysql-url}} MySQL]';
1040         }
1041
1042         /**
1043          * @return string
1044          */
1045         public function getServerVersion() {
1046                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1047                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1048                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1049                 if ( $this->serverVersion === null ) {
1050                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1051                 }
1052                 return $this->serverVersion;
1053         }
1054
1055         /**
1056          * @param array $options
1057          */
1058         public function setSessionOptions( array $options ) {
1059                 if ( isset( $options['connTimeout'] ) ) {
1060                         $timeout = (int)$options['connTimeout'];
1061                         $this->query( "SET net_read_timeout=$timeout" );
1062                         $this->query( "SET net_write_timeout=$timeout" );
1063                 }
1064         }
1065
1066         /**
1067          * @param string &$sql
1068          * @param string &$newLine
1069          * @return bool
1070          */
1071         public function streamStatementEnd( &$sql, &$newLine ) {
1072                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1073                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1074                         $this->delimiter = $m[1];
1075                         $newLine = '';
1076                 }
1077
1078                 return parent::streamStatementEnd( $sql, $newLine );
1079         }
1080
1081         /**
1082          * Check to see if a named lock is available. This is non-blocking.
1083          *
1084          * @param string $lockName Name of lock to poll
1085          * @param string $method Name of method calling us
1086          * @return bool
1087          * @since 1.20
1088          */
1089         public function lockIsFree( $lockName, $method ) {
1090                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1091                         return false; // already held
1092                 }
1093
1094                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1095                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1096                 $row = $this->fetchObject( $result );
1097
1098                 return ( $row->lockstatus == 1 );
1099         }
1100
1101         /**
1102          * @param string $lockName
1103          * @param string $method
1104          * @param int $timeout
1105          * @return bool
1106          */
1107         public function lock( $lockName, $method, $timeout = 5 ) {
1108                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1109                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1110                 $row = $this->fetchObject( $result );
1111
1112                 if ( $row->lockstatus == 1 ) {
1113                         parent::lock( $lockName, $method, $timeout ); // record
1114                         return true;
1115                 }
1116
1117                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1118                         [ 'lockname' => $lockName ] );
1119
1120                 return false;
1121         }
1122
1123         /**
1124          * FROM MYSQL DOCS:
1125          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1126          * @param string $lockName
1127          * @param string $method
1128          * @return bool
1129          */
1130         public function unlock( $lockName, $method ) {
1131                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1132                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1133                 $row = $this->fetchObject( $result );
1134
1135                 if ( $row->lockstatus == 1 ) {
1136                         parent::unlock( $lockName, $method ); // record
1137                         return true;
1138                 }
1139
1140                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1141
1142                 return false;
1143         }
1144
1145         private function makeLockName( $lockName ) {
1146                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1147                 // Newer version enforce a 64 char length limit.
1148                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1149         }
1150
1151         public function namedLocksEnqueue() {
1152                 return true;
1153         }
1154
1155         public function tableLocksHaveTransactionScope() {
1156                 return false; // tied to TCP connection
1157         }
1158
1159         protected function doLockTables( array $read, array $write, $method ) {
1160                 $items = [];
1161                 foreach ( $write as $table ) {
1162                         $items[] = $this->tableName( $table ) . ' WRITE';
1163                 }
1164                 foreach ( $read as $table ) {
1165                         $items[] = $this->tableName( $table ) . ' READ';
1166                 }
1167
1168                 $sql = "LOCK TABLES " . implode( ',', $items );
1169                 $this->query( $sql, $method );
1170
1171                 return true;
1172         }
1173
1174         protected function doUnlockTables( $method ) {
1175                 $this->query( "UNLOCK TABLES", $method );
1176
1177                 return true;
1178         }
1179
1180         /**
1181          * @param bool $value
1182          */
1183         public function setBigSelects( $value = true ) {
1184                 if ( $value === 'default' ) {
1185                         if ( $this->defaultBigSelects === null ) {
1186                                 # Function hasn't been called before so it must already be set to the default
1187                                 return;
1188                         } else {
1189                                 $value = $this->defaultBigSelects;
1190                         }
1191                 } elseif ( $this->defaultBigSelects === null ) {
1192                         $this->defaultBigSelects =
1193                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1194                 }
1195                 $encValue = $value ? '1' : '0';
1196                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1197         }
1198
1199         /**
1200          * DELETE where the condition is a join. MySql uses multi-table deletes.
1201          * @param string $delTable
1202          * @param string $joinTable
1203          * @param string $delVar
1204          * @param string $joinVar
1205          * @param array|string $conds
1206          * @param bool|string $fname
1207          * @throws DBUnexpectedError
1208          * @return bool|ResultWrapper
1209          */
1210         public function deleteJoin(
1211                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1212         ) {
1213                 if ( !$conds ) {
1214                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1215                 }
1216
1217                 $delTable = $this->tableName( $delTable );
1218                 $joinTable = $this->tableName( $joinTable );
1219                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1220
1221                 if ( $conds != '*' ) {
1222                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1223                 }
1224
1225                 return $this->query( $sql, $fname );
1226         }
1227
1228         /**
1229          * @param string $table
1230          * @param array $rows
1231          * @param array $uniqueIndexes
1232          * @param array $set
1233          * @param string $fname
1234          * @return bool
1235          */
1236         public function upsert( $table, array $rows, array $uniqueIndexes,
1237                 array $set, $fname = __METHOD__
1238         ) {
1239                 if ( !count( $rows ) ) {
1240                         return true; // nothing to do
1241                 }
1242
1243                 if ( !is_array( reset( $rows ) ) ) {
1244                         $rows = [ $rows ];
1245                 }
1246
1247                 $table = $this->tableName( $table );
1248                 $columns = array_keys( $rows[0] );
1249
1250                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1251                 $rowTuples = [];
1252                 foreach ( $rows as $row ) {
1253                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1254                 }
1255                 $sql .= implode( ',', $rowTuples );
1256                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1257
1258                 return (bool)$this->query( $sql, $fname );
1259         }
1260
1261         /**
1262          * Determines how long the server has been up
1263          *
1264          * @return int
1265          */
1266         public function getServerUptime() {
1267                 $vars = $this->getMysqlStatus( 'Uptime' );
1268
1269                 return (int)$vars['Uptime'];
1270         }
1271
1272         /**
1273          * Determines if the last failure was due to a deadlock
1274          *
1275          * @return bool
1276          */
1277         public function wasDeadlock() {
1278                 return $this->lastErrno() == 1213;
1279         }
1280
1281         /**
1282          * Determines if the last failure was due to a lock timeout
1283          *
1284          * @return bool
1285          */
1286         public function wasLockTimeout() {
1287                 return $this->lastErrno() == 1205;
1288         }
1289
1290         public function wasErrorReissuable() {
1291                 return $this->lastErrno() == 2013 || $this->lastErrno() == 2006;
1292         }
1293
1294         /**
1295          * Determines if the last failure was due to the database being read-only.
1296          *
1297          * @return bool
1298          */
1299         public function wasReadOnlyError() {
1300                 return $this->lastErrno() == 1223 ||
1301                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1302         }
1303
1304         public function wasConnectionError( $errno ) {
1305                 return $errno == 2013 || $errno == 2006;
1306         }
1307
1308         /**
1309          * @param string $oldName
1310          * @param string $newName
1311          * @param bool $temporary
1312          * @param string $fname
1313          * @return bool
1314          */
1315         public function duplicateTableStructure(
1316                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1317         ) {
1318                 $tmp = $temporary ? 'TEMPORARY ' : '';
1319                 $newName = $this->addIdentifierQuotes( $newName );
1320                 $oldName = $this->addIdentifierQuotes( $oldName );
1321                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1322
1323                 return $this->query( $query, $fname );
1324         }
1325
1326         /**
1327          * List all tables on the database
1328          *
1329          * @param string $prefix Only show tables with this prefix, e.g. mw_
1330          * @param string $fname Calling function name
1331          * @return array
1332          */
1333         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1334                 $result = $this->query( "SHOW TABLES", $fname );
1335
1336                 $endArray = [];
1337
1338                 foreach ( $result as $table ) {
1339                         $vars = get_object_vars( $table );
1340                         $table = array_pop( $vars );
1341
1342                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1343                                 $endArray[] = $table;
1344                         }
1345                 }
1346
1347                 return $endArray;
1348         }
1349
1350         /**
1351          * @param string $tableName
1352          * @param string $fName
1353          * @return bool|ResultWrapper
1354          */
1355         public function dropTable( $tableName, $fName = __METHOD__ ) {
1356                 if ( !$this->tableExists( $tableName, $fName ) ) {
1357                         return false;
1358                 }
1359
1360                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1361         }
1362
1363         /**
1364          * Get status information from SHOW STATUS in an associative array
1365          *
1366          * @param string $which
1367          * @return array
1368          */
1369         private function getMysqlStatus( $which = "%" ) {
1370                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1371                 $status = [];
1372
1373                 foreach ( $res as $row ) {
1374                         $status[$row->Variable_name] = $row->Value;
1375                 }
1376
1377                 return $status;
1378         }
1379
1380         /**
1381          * Lists VIEWs in the database
1382          *
1383          * @param string $prefix Only show VIEWs with this prefix, eg.
1384          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1385          * @param string $fname Name of calling function
1386          * @return array
1387          * @since 1.22
1388          */
1389         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1390                 // The name of the column containing the name of the VIEW
1391                 $propertyName = 'Tables_in_' . $this->dbName;
1392
1393                 // Query for the VIEWS
1394                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1395                 $allViews = [];
1396                 foreach ( $res as $row ) {
1397                         array_push( $allViews, $row->$propertyName );
1398                 }
1399
1400                 if ( is_null( $prefix ) || $prefix === '' ) {
1401                         return $allViews;
1402                 }
1403
1404                 $filteredViews = [];
1405                 foreach ( $allViews as $viewName ) {
1406                         // Does the name of this VIEW start with the table-prefix?
1407                         if ( strpos( $viewName, $prefix ) === 0 ) {
1408                                 array_push( $filteredViews, $viewName );
1409                         }
1410                 }
1411
1412                 return $filteredViews;
1413         }
1414
1415         /**
1416          * Differentiates between a TABLE and a VIEW.
1417          *
1418          * @param string $name Name of the TABLE/VIEW to test
1419          * @param string $prefix
1420          * @return bool
1421          * @since 1.22
1422          */
1423         public function isView( $name, $prefix = null ) {
1424                 return in_array( $name, $this->listViews( $prefix ) );
1425         }
1426
1427         /**
1428          * Allows for index remapping in queries where this is not consistent across DBMS
1429          *
1430          * @param string $index
1431          * @return string
1432          */
1433         protected function indexName( $index ) {
1434                 /**
1435                  * When SQLite indexes were introduced in r45764, it was noted that
1436                  * SQLite requires index names to be unique within the whole database,
1437                  * not just within a schema. As discussed in CR r45819, to avoid the
1438                  * need for a schema change on existing installations, the indexes
1439                  * were implicitly mapped from the new names to the old names.
1440                  *
1441                  * This mapping can be removed if DB patches are introduced to alter
1442                  * the relevant tables in existing installations. Note that because
1443                  * this index mapping applies to table creation, even new installations
1444                  * of MySQL have the old names (except for installations created during
1445                  * a period where this mapping was inappropriately removed, see
1446                  * T154872).
1447                  */
1448                 $renamed = [
1449                         'ar_usertext_timestamp' => 'usertext_timestamp',
1450                         'un_user_id' => 'user_id',
1451                         'un_user_ip' => 'user_ip',
1452                 ];
1453
1454                 if ( isset( $renamed[$index] ) ) {
1455                         return $renamed[$index];
1456                 } else {
1457                         return $index;
1458                 }
1459         }
1460
1461         protected function isTransactableQuery( $sql ) {
1462                 return parent::isTransactableQuery( $sql ) &&
1463                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1464         }
1465 }
1466
1467 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );