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 RuntimeException;
  31 use stdClass;
  32
  33 /**
  34  * Database abstraction object for MySQL.
  35  * Defines methods independent on used MySQL extension.
  36  *
  37  * @ingroup Database
  38  * @since 1.22
  39  * @see Database
  40  */
  41 abstract class DatabaseMysqlBase extends Database {
  42         /** @var MysqlMasterPos */
  43         protected $lastKnownReplicaPos;
  44         /** @var string Method to detect replica DB lag */
  45         protected $lagDetectionMethod;
  46         /** @var array Method to detect replica DB lag */
  47         protected $lagDetectionOptions = [];
  48         /** @var bool bool Whether to use GTID methods */
  49         protected $useGTIDs = false;
  50         /** @var string|null */
  51         protected $sslKeyPath;
  52         /** @var string|null */
  53         protected $sslCertPath;
  54         /** @var string|null */
  55         protected $sslCAFile;
  56         /** @var string|null */
  57         protected $sslCAPath;
  58         /** @var string[]|null */
  59         protected $sslCiphers;
  60         /** @var string sql_mode value to send on connection */
  61         protected $sqlMode;
  62         /** @var bool Use experimental UTF-8 transmission encoding */
  63         protected $utf8Mode;
  64         /** @var bool|null */
  65         protected $defaultBigSelects = null;
  66
  67         /** @var string|null */
  68         private $serverVersion = null;
  69         /** @var bool|null */
  70         private $insertSelectIsSafe = null;
  71         /** @var stdClass|null */
  72         private $replicationInfoRow = null;
  73
  74         // Cache getServerId() for 24 hours
  75         const SERVER_ID_CACHE_TTL = 86400;
  76
  77         /** @var float Warn if lag estimates are made for transactions older than this many seconds */
  78         const LAG_STALE_WARN_THRESHOLD = 0.100;
  79
  80         /**
  81          * Additional $params include:
  82          *   - lagDetectionMethod : set to one of (Seconds_Behind_Master,pt-heartbeat).
  83          *       pt-heartbeat assumes the table is at heartbeat.heartbeat
  84          *       and uses UTC timestamps in the heartbeat.ts column.
  85          *       (https://www.percona.com/doc/percona-toolkit/2.2/pt-heartbeat.html)
  86          *   - lagDetectionOptions : if using pt-heartbeat, this can be set to an array map to change
  87          *       the default behavior. Normally, the heartbeat row with the server
  88          *       ID of this server's master will be used. Set the "conds" field to
  89          *       override the query conditions, e.g. ['shard' => 's1'].
  90          *   - useGTIDs : use GTID methods like MASTER_GTID_WAIT() when possible.
  91          *   - insertSelectIsSafe : force that native INSERT SELECT is or is not safe [default: null]
  92          *   - sslKeyPath : path to key file [default: null]
  93          *   - sslCertPath : path to certificate file [default: null]
  94          *   - sslCAFile: path to a single certificate authority PEM file [default: null]
  95          *   - sslCAPath : parth to certificate authority PEM directory [default: null]
  96          *   - sslCiphers : array list of allowable ciphers [default: null]
  97          * @param array $params
  98          */
  99         function __construct( array $params ) {
 100                 $this->lagDetectionMethod = $params['lagDetectionMethod'] ?? 'Seconds_Behind_Master';
 101                 $this->lagDetectionOptions = $params['lagDetectionOptions'] ?? [];
 102                 $this->useGTIDs = !empty( $params['useGTIDs' ] );
 103                 foreach ( [ 'KeyPath', 'CertPath', 'CAFile', 'CAPath', 'Ciphers' ] as $name ) {
 104                         $var = "ssl{$name}";
 105                         if ( isset( $params[$var] ) ) {
 106                                 $this->$var = $params[$var];
 107                         }
 108                 }
 109                 $this->sqlMode = $params['sqlMode'] ?? '';
 110                 $this->utf8Mode = !empty( $params['utf8Mode'] );
 111                 $this->insertSelectIsSafe = isset( $params['insertSelectIsSafe'] )
 112                         ? (bool)$params['insertSelectIsSafe'] : null;
 113
 114                 parent::__construct( $params );
 115         }
 116
 117         /**
 118          * @return string
 119          */
 120         public function getType() {
 121                 return 'mysql';
 122         }
 123
 124         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
 125                 # Close/unset connection handle
 126                 $this->close();
 127
 128                 $this->server = $server;
 129                 $this->user = $user;
 130                 $this->password = $password;
 131
 132                 $this->installErrorHandler();
 133                 try {
 134                         $this->conn = $this->mysqlConnect( $this->server, $dbName );
 135                 } catch ( Exception $ex ) {
 136                         $this->restoreErrorHandler();
 137                         throw $ex;
 138                 }
 139                 $error = $this->restoreErrorHandler();
 140
 141                 # Always log connection errors
 142                 if ( !$this->conn ) {
 143                         $error = $error ?: $this->lastError();
 144                         $this->connLogger->error(
 145                                 "Error connecting to {db_server}: {error}",
 146                                 $this->getLogContext( [
 147                                         'method' => __METHOD__,
 148                                         'error' => $error,
 149                                 ] )
 150                         );
 151                         $this->connLogger->debug( "DB connection error\n" .
 152                                 "Server: $server, User: $user, Password: " .
 153                                 substr( $password, 0, 3 ) . "..., error: " . $error . "\n" );
 154
 155                         throw new DBConnectionError( $this, $error );
 156                 }
 157
 158                 if ( strlen( $dbName ) ) {
 159                         $this->selectDomain( new DatabaseDomain( $dbName, null, $tablePrefix ) );
 160                 } else {
 161                         $this->currentDomain = new DatabaseDomain( null, null, $tablePrefix );
 162                 }
 163
 164                 // Tell the server what we're communicating with
 165                 if ( !$this->connectInitCharset() ) {
 166                         $error = $this->lastError();
 167                         $this->queryLogger->error(
 168                                 "Error setting character set: {error}",
 169                                 $this->getLogContext( [
 170                                         'method' => __METHOD__,
 171                                         'error' => $this->lastError(),
 172                                 ] )
 173                         );
 174                         throw new DBConnectionError( $this, "Error setting character set: $error" );
 175                 }
 176
 177                 // Abstract over any insane MySQL defaults
 178                 $set = [ 'group_concat_max_len = 262144' ];
 179                 // Set SQL mode, default is turning them all off, can be overridden or skipped with null
 180                 if ( is_string( $this->sqlMode ) ) {
 181                         $set[] = 'sql_mode = ' . $this->addQuotes( $this->sqlMode );
 182                 }
 183                 // Set any custom settings defined by site config
 184                 // (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
 185                 foreach ( $this->sessionVars as $var => $val ) {
 186                         // Escape strings but not numbers to avoid MySQL complaining
 187                         if ( !is_int( $val ) && !is_float( $val ) ) {
 188                                 $val = $this->addQuotes( $val );
 189                         }
 190                         $set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
 191                 }
 192
 193                 if ( $set ) {
 194                         // Use doQuery() to avoid opening implicit transactions (DBO_TRX)
 195                         $success = $this->doQuery( 'SET ' . implode( ', ', $set ) );
 196                         if ( !$success ) {
 197                                 $error = $this->lastError();
 198                                 $this->queryLogger->error(
 199                                         'Error setting MySQL variables on server {db_server}: {error}',
 200                                         $this->getLogContext( [
 201                                                 'method' => __METHOD__,
 202                                                 'error' => $error,
 203                                         ] )
 204                                 );
 205                                 throw new DBConnectionError( $this, "Error setting MySQL variables: $error" );
 206                         }
 207                 }
 208
 209                 $this->opened = true;
 210
 211                 return true;
 212         }
 213
 214         /**
 215          * Set the character set information right after connection
 216          * @return bool
 217          */
 218         protected function connectInitCharset() {
 219                 if ( $this->utf8Mode ) {
 220                         // Tell the server we're communicating with it in UTF-8.
 221                         // This may engage various charset conversions.
 222                         return $this->mysqlSetCharset( 'utf8' );
 223                 } else {
 224                         return $this->mysqlSetCharset( 'binary' );
 225                 }
 226         }
 227
 228         /**
 229          * Open a connection to a MySQL server
 230          *
 231          * @param string $realServer
 232          * @param string|null $dbName
 233          * @return mixed Raw connection
 234          * @throws DBConnectionError
 235          */
 236         abstract protected function mysqlConnect( $realServer, $dbName );
 237
 238         /**
 239          * Set the character set of the MySQL link
 240          *
 241          * @param string $charset
 242          * @return bool
 243          */
 244         abstract protected function mysqlSetCharset( $charset );
 245
 246         /**
 247          * @param ResultWrapper|resource $res
 248          * @throws DBUnexpectedError
 249          */
 250         public function freeResult( $res ) {
 251                 if ( $res instanceof ResultWrapper ) {
 252                         $res = $res->result;
 253                 }
 254                 Wikimedia\suppressWarnings();
 255                 $ok = $this->mysqlFreeResult( $res );
 256                 Wikimedia\restoreWarnings();
 257                 if ( !$ok ) {
 258                         throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 259                 }
 260         }
 261
 262         /**
 263          * Free result memory
 264          *
 265          * @param resource $res Raw result
 266          * @return bool
 267          */
 268         abstract protected function mysqlFreeResult( $res );
 269
 270         /**
 271          * @param ResultWrapper|resource $res
 272          * @return stdClass|bool
 273          * @throws DBUnexpectedError
 274          */
 275         public function fetchObject( $res ) {
 276                 if ( $res instanceof ResultWrapper ) {
 277                         $res = $res->result;
 278                 }
 279                 Wikimedia\suppressWarnings();
 280                 $row = $this->mysqlFetchObject( $res );
 281                 Wikimedia\restoreWarnings();
 282
 283                 $errno = $this->lastErrno();
 284                 // Unfortunately, mysql_fetch_object does not reset the last errno.
 285                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 286                 // these are the only errors mysql_fetch_object can cause.
 287                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 288                 if ( $errno == 2000 || $errno == 2013 ) {
 289                         throw new DBUnexpectedError(
 290                                 $this,
 291                                 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() )
 292                         );
 293                 }
 294
 295                 return $row;
 296         }
 297
 298         /**
 299          * Fetch a result row as an object
 300          *
 301          * @param resource $res Raw result
 302          * @return stdClass
 303          */
 304         abstract protected function mysqlFetchObject( $res );
 305
 306         /**
 307          * @param IResultWrapper|resource $res
 308          * @return array|bool
 309          * @throws DBUnexpectedError
 310          */
 311         public function fetchRow( $res ) {
 312                 if ( $res instanceof ResultWrapper ) {
 313                         $res = $res->result;
 314                 }
 315                 Wikimedia\suppressWarnings();
 316                 $row = $this->mysqlFetchArray( $res );
 317                 Wikimedia\restoreWarnings();
 318
 319                 $errno = $this->lastErrno();
 320                 // Unfortunately, mysql_fetch_array does not reset the last errno.
 321                 // Only check for CR_SERVER_LOST and CR_UNKNOWN_ERROR, as
 322                 // these are the only errors mysql_fetch_array can cause.
 323                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 324                 if ( $errno == 2000 || $errno == 2013 ) {
 325                         throw new DBUnexpectedError(
 326                                 $this,
 327                                 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() )
 328                         );
 329                 }
 330
 331                 return $row;
 332         }
 333
 334         /**
 335          * Fetch a result row as an associative and numeric array
 336          *
 337          * @param resource $res Raw result
 338          * @return array
 339          */
 340         abstract protected function mysqlFetchArray( $res );
 341
 342         /**
 343          * @throws DBUnexpectedError
 344          * @param ResultWrapper|resource $res
 345          * @return int
 346          */
 347         function numRows( $res ) {
 348                 if ( $res instanceof ResultWrapper ) {
 349                         $res = $res->result;
 350                 }
 351                 Wikimedia\suppressWarnings();
 352                 $n = !is_bool( $res ) ? $this->mysqlNumRows( $res ) : 0;
 353                 Wikimedia\restoreWarnings();
 354
 355                 // Unfortunately, mysql_num_rows does not reset the last errno.
 356                 // We are not checking for any errors here, since
 357                 // there are no errors mysql_num_rows can cause.
 358                 // See https://dev.mysql.com/doc/refman/5.0/en/mysql-fetch-row.html.
 359                 // See https://phabricator.wikimedia.org/T44430
 360                 return $n;
 361         }
 362
 363         /**
 364          * Get number of rows in result
 365          *
 366          * @param resource $res Raw result
 367          * @return int
 368          */
 369         abstract protected function mysqlNumRows( $res );
 370
 371         /**
 372          * @param ResultWrapper|resource $res
 373          * @return int
 374          */
 375         public function numFields( $res ) {
 376                 if ( $res instanceof ResultWrapper ) {
 377                         $res = $res->result;
 378                 }
 379
 380                 return $this->mysqlNumFields( $res );
 381         }
 382
 383         /**
 384          * Get number of fields in result
 385          *
 386          * @param resource $res Raw result
 387          * @return int
 388          */
 389         abstract protected function mysqlNumFields( $res );
 390
 391         /**
 392          * @param ResultWrapper|resource $res
 393          * @param int $n
 394          * @return string
 395          */
 396         public function fieldName( $res, $n ) {
 397                 if ( $res instanceof ResultWrapper ) {
 398                         $res = $res->result;
 399                 }
 400
 401                 return $this->mysqlFieldName( $res, $n );
 402         }
 403
 404         /**
 405          * Get the name of the specified field in a result
 406          *
 407          * @param ResultWrapper|resource $res
 408          * @param int $n
 409          * @return string
 410          */
 411         abstract protected function mysqlFieldName( $res, $n );
 412
 413         /**
 414          * mysql_field_type() wrapper
 415          * @param ResultWrapper|resource $res
 416          * @param int $n
 417          * @return string
 418          */
 419         public function fieldType( $res, $n ) {
 420                 if ( $res instanceof ResultWrapper ) {
 421                         $res = $res->result;
 422                 }
 423
 424                 return $this->mysqlFieldType( $res, $n );
 425         }
 426
 427         /**
 428          * Get the type of the specified field in a result
 429          *
 430          * @param ResultWrapper|resource $res
 431          * @param int $n
 432          * @return string
 433          */
 434         abstract protected function mysqlFieldType( $res, $n );
 435
 436         /**
 437          * @param ResultWrapper|resource $res
 438          * @param int $row
 439          * @return bool
 440          */
 441         public function dataSeek( $res, $row ) {
 442                 if ( $res instanceof ResultWrapper ) {
 443                         $res = $res->result;
 444                 }
 445
 446                 return $this->mysqlDataSeek( $res, $row );
 447         }
 448
 449         /**
 450          * Move internal result pointer
 451          *
 452          * @param ResultWrapper|resource $res
 453          * @param int $row
 454          * @return bool
 455          */
 456         abstract protected function mysqlDataSeek( $res, $row );
 457
 458         /**
 459          * @return string
 460          */
 461         public function lastError() {
 462                 if ( $this->conn ) {
 463                         # Even if it's non-zero, it can still be invalid
 464                         Wikimedia\suppressWarnings();
 465                         $error = $this->mysqlError( $this->conn );
 466                         if ( !$error ) {
 467                                 $error = $this->mysqlError();
 468                         }
 469                         Wikimedia\restoreWarnings();
 470                 } else {
 471                         $error = $this->mysqlError();
 472                 }
 473                 if ( $error ) {
 474                         $error .= ' (' . $this->server . ')';
 475                 }
 476
 477                 return $error;
 478         }
 479
 480         /**
 481          * Returns the text of the error message from previous MySQL operation
 482          *
 483          * @param resource|null $conn Raw connection
 484          * @return string
 485          */
 486         abstract protected function mysqlError( $conn = null );
 487
 488         protected function wasQueryTimeout( $error, $errno ) {
 489                 // https://dev.mysql.com/doc/refman/8.0/en/client-error-reference.html
 490                 // https://phabricator.wikimedia.org/T170638
 491                 return in_array( $errno, [ 2062, 3024 ] );
 492         }
 493
 494         public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
 495                 $this->nativeReplace( $table, $rows, $fname );
 496         }
 497
 498         protected function isInsertSelectSafe( array $insertOptions, array $selectOptions ) {
 499                 $row = $this->getReplicationSafetyInfo();
 500                 // For row-based-replication, the resulting changes will be relayed, not the query
 501                 if ( $row->binlog_format === 'ROW' ) {
 502                         return true;
 503                 }
 504                 // LIMIT requires ORDER BY on a unique key or it is non-deterministic
 505                 if ( isset( $selectOptions['LIMIT'] ) ) {
 506                         return false;
 507                 }
 508                 // In MySQL, an INSERT SELECT is only replication safe with row-based
 509                 // replication or if innodb_autoinc_lock_mode is 0. When those
 510                 // conditions aren't met, use non-native mode.
 511                 // While we could try to determine if the insert is safe anyway by
 512                 // checking if the target table has an auto-increment column that
 513                 // isn't set in $varMap, that seems unlikely to be worth the extra
 514                 // complexity.
 515                 return (
 516                         in_array( 'NO_AUTO_COLUMNS', $insertOptions ) ||
 517                         (int)$row->innodb_autoinc_lock_mode === 0
 518                 );
 519         }
 520
 521         /**
 522          * @return stdClass Process cached row
 523          */
 524         protected function getReplicationSafetyInfo() {
 525                 if ( $this->replicationInfoRow === null ) {
 526                         $this->replicationInfoRow = $this->selectRow(
 527                                 false,
 528                                 [
 529                                         'innodb_autoinc_lock_mode' => '@@innodb_autoinc_lock_mode',
 530                                         'binlog_format' => '@@binlog_format',
 531                                 ],
 532                                 [],
 533                                 __METHOD__
 534                         );
 535                 }
 536
 537                 return $this->replicationInfoRow;
 538         }
 539
 540         /**
 541          * Estimate rows in dataset
 542          * Returns estimated count, based on EXPLAIN output
 543          * Takes same arguments as Database::select()
 544          *
 545          * @param string|array $table
 546          * @param string|array $var
 547          * @param string|array $conds
 548          * @param string $fname
 549          * @param string|array $options
 550          * @param array $join_conds
 551          * @return bool|int
 552          */
 553         public function estimateRowCount( $table, $var = '*', $conds = '',
 554                 $fname = __METHOD__, $options = [], $join_conds = []
 555         ) {
 556                 $conds = $this->normalizeConditions( $conds, $fname );
 557                 $column = $this->extractSingleFieldFromList( $var );
 558                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 559                         $conds[] = "$column IS NOT NULL";
 560                 }
 561
 562                 $options['EXPLAIN'] = true;
 563                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 564                 if ( $res === false ) {
 565                         return false;
 566                 }
 567                 if ( !$this->numRows( $res ) ) {
 568                         return 0;
 569                 }
 570
 571                 $rows = 1;
 572                 foreach ( $res as $plan ) {
 573                         $rows *= $plan->rows > 0 ? $plan->rows : 1; // avoid resetting to zero
 574                 }
 575
 576                 return (int)$rows;
 577         }
 578
 579         public function tableExists( $table, $fname = __METHOD__ ) {
 580                 // Split database and table into proper variables as Database::tableName() returns
 581                 // shared tables prefixed with their database, which do not work in SHOW TABLES statements
 582                 list( $database, , $prefix, $table ) = $this->qualifiedTableComponents( $table );
 583                 $tableName = "{$prefix}{$table}";
 584
 585                 if ( isset( $this->sessionTempTables[$tableName] ) ) {
 586                         return true; // already known to exist and won't show in SHOW TABLES anyway
 587                 }
 588
 589                 // We can't use buildLike() here, because it specifies an escape character
 590                 // other than the backslash, which is the only one supported by SHOW TABLES
 591                 $encLike = $this->escapeLikeInternal( $tableName, '\\' );
 592
 593                 // If the database has been specified (such as for shared tables), use "FROM"
 594                 if ( $database !== '' ) {
 595                         $encDatabase = $this->addIdentifierQuotes( $database );
 596                         $query = "SHOW TABLES FROM $encDatabase LIKE '$encLike'";
 597                 } else {
 598                         $query = "SHOW TABLES LIKE '$encLike'";
 599                 }
 600
 601                 return $this->query( $query, $fname )->numRows() > 0;
 602         }
 603
 604         /**
 605          * @param string $table
 606          * @param string $field
 607          * @return bool|MySQLField
 608          */
 609         public function fieldInfo( $table, $field ) {
 610                 $table = $this->tableName( $table );
 611                 $res = $this->query( "SELECT * FROM $table LIMIT 1", __METHOD__, true );
 612                 if ( !$res ) {
 613                         return false;
 614                 }
 615                 $n = $this->mysqlNumFields( $res->result );
 616                 for ( $i = 0; $i < $n; $i++ ) {
 617                         $meta = $this->mysqlFetchField( $res->result, $i );
 618                         if ( $field == $meta->name ) {
 619                                 return new MySQLField( $meta );
 620                         }
 621                 }
 622
 623                 return false;
 624         }
 625
 626         /**
 627          * Get column information from a result
 628          *
 629          * @param resource $res Raw result
 630          * @param int $n
 631          * @return stdClass
 632          */
 633         abstract protected function mysqlFetchField( $res, $n );
 634
 635         /**
 636          * Get information about an index into an object
 637          * Returns false if the index does not exist
 638          *
 639          * @param string $table
 640          * @param string $index
 641          * @param string $fname
 642          * @return bool|array|null False or null on failure
 643          */
 644         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 645                 # SHOW INDEX works in MySQL 3.23.58, but SHOW INDEXES does not.
 646                 # SHOW INDEX should work for 3.x and up:
 647                 # https://dev.mysql.com/doc/mysql/en/SHOW_INDEX.html
 648                 $table = $this->tableName( $table );
 649                 $index = $this->indexName( $index );
 650
 651                 $sql = 'SHOW INDEX FROM ' . $table;
 652                 $res = $this->query( $sql, $fname );
 653
 654                 if ( !$res ) {
 655                         return null;
 656                 }
 657
 658                 $result = [];
 659
 660                 foreach ( $res as $row ) {
 661                         if ( $row->Key_name == $index ) {
 662                                 $result[] = $row;
 663                         }
 664                 }
 665
 666                 return $result ?: false;
 667         }
 668
 669         /**
 670          * @param string $s
 671          * @return string
 672          */
 673         public function strencode( $s ) {
 674                 return $this->mysqlRealEscapeString( $s );
 675         }
 676
 677         /**
 678          * @param string $s
 679          * @return mixed
 680          */
 681         abstract protected function mysqlRealEscapeString( $s );
 682
 683         public function addQuotes( $s ) {
 684                 if ( is_bool( $s ) ) {
 685                         // Parent would transform to int, which does not play nice with MySQL type juggling.
 686                         // When searching for an int in a string column, the strings are cast to int, which
 687                         // means false would match any string not starting with a number.
 688                         $s = (string)(int)$s;
 689                 }
 690                 return parent::addQuotes( $s );
 691         }
 692
 693         /**
 694          * MySQL uses `backticks` for identifier quoting instead of the sql standard "double quotes".
 695          *
 696          * @param string $s
 697          * @return string
 698          */
 699         public function addIdentifierQuotes( $s ) {
 700                 // Characters in the range \u0001-\uFFFF are valid in a quoted identifier
 701                 // Remove NUL bytes and escape backticks by doubling
 702                 return '`' . str_replace( [ "\0", '`' ], [ '', '``' ], $s ) . '`';
 703         }
 704
 705         /**
 706          * @param string $name
 707          * @return bool
 708          */
 709         public function isQuotedIdentifier( $name ) {
 710                 return strlen( $name ) && $name[0] == '`' && substr( $name, -1, 1 ) == '`';
 711         }
 712
 713         public function getLag() {
 714                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 715                         return $this->getLagFromPtHeartbeat();
 716                 } else {
 717                         return $this->getLagFromSlaveStatus();
 718                 }
 719         }
 720
 721         /**
 722          * @return string
 723          */
 724         protected function getLagDetectionMethod() {
 725                 return $this->lagDetectionMethod;
 726         }
 727
 728         /**
 729          * @return bool|int
 730          */
 731         protected function getLagFromSlaveStatus() {
 732                 $res = $this->query( 'SHOW SLAVE STATUS', __METHOD__ );
 733                 $row = $res ? $res->fetchObject() : false;
 734                 // If the server is not replicating, there will be no row
 735                 if ( $row && strval( $row->Seconds_Behind_Master ) !== '' ) {
 736                         return intval( $row->Seconds_Behind_Master );
 737                 }
 738
 739                 return false;
 740         }
 741
 742         /**
 743          * @return bool|float
 744          */
 745         protected function getLagFromPtHeartbeat() {
 746                 $options = $this->lagDetectionOptions;
 747
 748                 $currentTrxInfo = $this->getRecordedTransactionLagStatus();
 749                 if ( $currentTrxInfo ) {
 750                         // There is an active transaction and the initial lag was already queried
 751                         $staleness = microtime( true ) - $currentTrxInfo['since'];
 752                         if ( $staleness > self::LAG_STALE_WARN_THRESHOLD ) {
 753                                 // Avoid returning higher and higher lag value due to snapshot age
 754                                 // given that the isolation level will typically be REPEATABLE-READ
 755                                 $this->queryLogger->warning(
 756                                         "Using cached lag value for {db_server} due to active transaction",
 757                                         $this->getLogContext( [
 758                                                 'method' => __METHOD__,
 759                                                 'age' => $staleness,
 760                                                 'trace' => ( new RuntimeException() )->getTraceAsString()
 761                                         ] )
 762                                 );
 763                         }
 764
 765                         return $currentTrxInfo['lag'];
 766                 }
 767
 768                 if ( isset( $options['conds'] ) ) {
 769                         // Best method for multi-DC setups: use logical channel names
 770                         $data = $this->getHeartbeatData( $options['conds'] );
 771                 } else {
 772                         // Standard method: use master server ID (works with stock pt-heartbeat)
 773                         $masterInfo = $this->getMasterServerInfo();
 774                         if ( !$masterInfo ) {
 775                                 $this->queryLogger->error(
 776                                         "Unable to query master of {db_server} for server ID",
 777                                         $this->getLogContext( [
 778                                                 'method' => __METHOD__
 779                                         ] )
 780                                 );
 781
 782                                 return false; // could not get master server ID
 783                         }
 784
 785                         $conds = [ 'server_id' => intval( $masterInfo['serverId'] ) ];
 786                         $data = $this->getHeartbeatData( $conds );
 787                 }
 788
 789                 list( $time, $nowUnix ) = $data;
 790                 if ( $time !== null ) {
 791                         // @time is in ISO format like "2015-09-25T16:48:10.000510"
 792                         $dateTime = new DateTime( $time, new DateTimeZone( 'UTC' ) );
 793                         $timeUnix = (int)$dateTime->format( 'U' ) + $dateTime->format( 'u' ) / 1e6;
 794
 795                         return max( $nowUnix - $timeUnix, 0.0 );
 796                 }
 797
 798                 $this->queryLogger->error(
 799                         "Unable to find pt-heartbeat row for {db_server}",
 800                         $this->getLogContext( [
 801                                 'method' => __METHOD__
 802                         ] )
 803                 );
 804
 805                 return false;
 806         }
 807
 808         protected function getMasterServerInfo() {
 809                 $cache = $this->srvCache;
 810                 $key = $cache->makeGlobalKey(
 811                         'mysql',
 812                         'master-info',
 813                         // Using one key for all cluster replica DBs is preferable
 814                         $this->getLBInfo( 'clusterMasterHost' ) ?: $this->getServer()
 815                 );
 816                 $fname = __METHOD__;
 817
 818                 return $cache->getWithSetCallback(
 819                         $key,
 820                         $cache::TTL_INDEFINITE,
 821                         function () use ( $cache, $key, $fname ) {
 822                                 // Get and leave a lock key in place for a short period
 823                                 if ( !$cache->lock( $key, 0, 10 ) ) {
 824                                         return false; // avoid master connection spike slams
 825                                 }
 826
 827                                 $conn = $this->getLazyMasterHandle();
 828                                 if ( !$conn ) {
 829                                         return false; // something is misconfigured
 830                                 }
 831
 832                                 // Connect to and query the master; catch errors to avoid outages
 833                                 try {
 834                                         $res = $conn->query( 'SELECT @@server_id AS id', $fname );
 835                                         $row = $res ? $res->fetchObject() : false;
 836                                         $id = $row ? (int)$row->id : 0;
 837                                 } catch ( DBError $e ) {
 838                                         $id = 0;
 839                                 }
 840
 841                                 // Cache the ID if it was retrieved
 842                                 return $id ? [ 'serverId' => $id, 'asOf' => time() ] : false;
 843                         }
 844                 );
 845         }
 846
 847         /**
 848          * @param array $conds WHERE clause conditions to find a row
 849          * @return array (heartbeat `ts` column value or null, UNIX timestamp) for the newest beat
 850          * @see https://www.percona.com/doc/percona-toolkit/2.1/pt-heartbeat.html
 851          */
 852         protected function getHeartbeatData( array $conds ) {
 853                 // Query time and trip time are not counted
 854                 $nowUnix = microtime( true );
 855                 // Do not bother starting implicit transactions here
 856                 $this->clearFlag( self::DBO_TRX, self::REMEMBER_PRIOR );
 857                 try {
 858                         $whereSQL = $this->makeList( $conds, self::LIST_AND );
 859                         // Use ORDER BY for channel based queries since that field might not be UNIQUE.
 860                         // Note: this would use "TIMESTAMPDIFF(MICROSECOND,ts,UTC_TIMESTAMP(6))" but the
 861                         // percision field is not supported in MySQL <= 5.5.
 862                         $res = $this->query(
 863                                 "SELECT ts FROM heartbeat.heartbeat WHERE $whereSQL ORDER BY ts DESC LIMIT 1",
 864                                 __METHOD__
 865                         );
 866                         $row = $res ? $res->fetchObject() : false;
 867                 } finally {
 868                         $this->restoreFlags();
 869                 }
 870
 871                 return [ $row ? $row->ts : null, $nowUnix ];
 872         }
 873
 874         protected function getApproximateLagStatus() {
 875                 if ( $this->getLagDetectionMethod() === 'pt-heartbeat' ) {
 876                         // Disable caching since this is fast enough and we don't wan't
 877                         // to be *too* pessimistic by having both the cache TTL and the
 878                         // pt-heartbeat interval count as lag in getSessionLagStatus()
 879                         return parent::getApproximateLagStatus();
 880                 }
 881
 882                 $key = $this->srvCache->makeGlobalKey( 'mysql-lag', $this->getServer() );
 883                 $approxLag = $this->srvCache->get( $key );
 884                 if ( !$approxLag ) {
 885                         $approxLag = parent::getApproximateLagStatus();
 886                         $this->srvCache->set( $key, $approxLag, 1 );
 887                 }
 888
 889                 return $approxLag;
 890         }
 891
 892         public function masterPosWait( DBMasterPos $pos, $timeout ) {
 893                 if ( !( $pos instanceof MySQLMasterPos ) ) {
 894                         throw new InvalidArgumentException( "Position not an instance of MySQLMasterPos" );
 895                 }
 896
 897                 if ( $this->getLBInfo( 'is static' ) === true ) {
 898                         return 0; // this is a copy of a read-only dataset with no master DB
 899                 } elseif ( $this->lastKnownReplicaPos && $this->lastKnownReplicaPos->hasReached( $pos ) ) {
 900                         return 0; // already reached this point for sure
 901                 }
 902
 903                 // Call doQuery() directly, to avoid opening a transaction if DBO_TRX is set
 904                 if ( $pos->getGTIDs() ) {
 905                         // Ignore GTIDs from domains exclusive to the master DB (presumably inactive)
 906                         $rpos = $this->getReplicaPos();
 907                         $gtidsWait = $rpos ? MySQLMasterPos::getCommonDomainGTIDs( $pos, $rpos ) : [];
 908                         if ( !$gtidsWait ) {
 909                                 $this->queryLogger->error(
 910                                         "No GTIDs with the same domain between master ($pos) and replica ($rpos)",
 911                                         $this->getLogContext( [
 912                                                 'method' => __METHOD__,
 913                                         ] )
 914                                 );
 915
 916                                 return -1; // $pos is from the wrong cluster?
 917                         }
 918                         // Wait on the GTID set (MariaDB only)
 919                         $gtidArg = $this->addQuotes( implode( ',', $gtidsWait ) );
 920                         if ( strpos( $gtidArg, ':' ) !== false ) {
 921                                 // MySQL GTIDs, e.g "source_id:transaction_id"
 922                                 $res = $this->doQuery( "SELECT WAIT_FOR_EXECUTED_GTID_SET($gtidArg, $timeout)" );
 923                         } else {
 924                                 // MariaDB GTIDs, e.g."domain:server:sequence"
 925                                 $res = $this->doQuery( "SELECT MASTER_GTID_WAIT($gtidArg, $timeout)" );
 926                         }
 927                 } else {
 928                         // Wait on the binlog coordinates
 929                         $encFile = $this->addQuotes( $pos->getLogFile() );
 930                         $encPos = intval( $pos->getLogPosition()[$pos::CORD_EVENT] );
 931                         $res = $this->doQuery( "SELECT MASTER_POS_WAIT($encFile, $encPos, $timeout)" );
 932                 }
 933
 934                 $row = $res ? $this->fetchRow( $res ) : false;
 935                 if ( !$row ) {
 936                         throw new DBExpectedError( $this, "Replication wait failed: {$this->lastError()}" );
 937                 }
 938
 939                 // Result can be NULL (error), -1 (timeout), or 0+ per the MySQL manual
 940                 $status = ( $row[0] !== null ) ? intval( $row[0] ) : null;
 941                 if ( $status === null ) {
 942                         if ( !$pos->getGTIDs() ) {
 943                                 // T126436: jobs programmed to wait on master positions might be referencing
 944                                 // binlogs with an old master hostname; this makes MASTER_POS_WAIT() return null.
 945                                 // Try to detect this case and treat the replica DB as having reached the given
 946                                 // position (any master switchover already requires that the new master be caught
 947                                 // up before the switch).
 948                                 $replicationPos = $this->getReplicaPos();
 949                                 if ( $replicationPos && !$replicationPos->channelsMatch( $pos ) ) {
 950                                         $this->lastKnownReplicaPos = $replicationPos;
 951                                         $status = 0;
 952                                 }
 953                         }
 954                 } elseif ( $status >= 0 ) {
 955                         // Remember that this position was reached to save queries next time
 956                         $this->lastKnownReplicaPos = $pos;
 957                 }
 958
 959                 return $status;
 960         }
 961
 962         /**
 963          * Get the position of the master from SHOW SLAVE STATUS
 964          *
 965          * @return MySQLMasterPos|bool
 966          */
 967         public function getReplicaPos() {
 968                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 969
 970                 if ( $this->useGTIDs() ) {
 971                         // Try to use GTIDs, fallbacking to binlog positions if not possible
 972                         $data = $this->getServerGTIDs( __METHOD__ );
 973                         // Use gtid_slave_pos for MariaDB and gtid_executed for MySQL
 974                         foreach ( [ 'gtid_slave_pos', 'gtid_executed' ] as $name ) {
 975                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
 976                                         return new MySQLMasterPos( $data[$name], $now );
 977                                 }
 978                         }
 979                 }
 980
 981                 $data = $this->getServerRoleStatus( 'SLAVE', __METHOD__ );
 982                 if ( $data && strlen( $data['Relay_Master_Log_File'] ) ) {
 983                         return new MySQLMasterPos(
 984                                 "{$data['Relay_Master_Log_File']}/{$data['Exec_Master_Log_Pos']}",
 985                                 $now
 986                         );
 987                 }
 988
 989                 return false;
 990         }
 991
 992         /**
 993          * Get the position of the master from SHOW MASTER STATUS
 994          *
 995          * @return MySQLMasterPos|bool
 996          */
 997         public function getMasterPos() {
 998                 $now = microtime( true ); // as-of-time *before* fetching GTID variables
 999
1000                 $pos = false;
1001                 if ( $this->useGTIDs() ) {
1002                         // Try to use GTIDs, fallbacking to binlog positions if not possible
1003                         $data = $this->getServerGTIDs( __METHOD__ );
1004                         // Use gtid_binlog_pos for MariaDB and gtid_executed for MySQL
1005                         foreach ( [ 'gtid_binlog_pos', 'gtid_executed' ] as $name ) {
1006                                 if ( isset( $data[$name] ) && strlen( $data[$name] ) ) {
1007                                         $pos = new MySQLMasterPos( $data[$name], $now );
1008                                         break;
1009                                 }
1010                         }
1011                         // Filter domains that are inactive or not relevant to the session
1012                         if ( $pos ) {
1013                                 $pos->setActiveOriginServerId( $this->getServerId() );
1014                                 $pos->setActiveOriginServerUUID( $this->getServerUUID() );
1015                                 if ( isset( $data['gtid_domain_id'] ) ) {
1016                                         $pos->setActiveDomain( $data['gtid_domain_id'] );
1017                                 }
1018                         }
1019                 }
1020
1021                 if ( !$pos ) {
1022                         $data = $this->getServerRoleStatus( 'MASTER', __METHOD__ );
1023                         if ( $data && strlen( $data['File'] ) ) {
1024                                 $pos = new MySQLMasterPos( "{$data['File']}/{$data['Position']}", $now );
1025                         }
1026                 }
1027
1028                 return $pos;
1029         }
1030
1031         /**
1032          * @return int
1033          * @throws DBQueryError If the variable doesn't exist for some reason
1034          */
1035         protected function getServerId() {
1036                 $fname = __METHOD__;
1037                 return $this->srvCache->getWithSetCallback(
1038                         $this->srvCache->makeGlobalKey( 'mysql-server-id', $this->getServer() ),
1039                         self::SERVER_ID_CACHE_TTL,
1040                         function () use ( $fname ) {
1041                                 $res = $this->query( "SELECT @@server_id AS id", $fname );
1042                                 return intval( $this->fetchObject( $res )->id );
1043                         }
1044                 );
1045         }
1046
1047         /**
1048          * @return string|null
1049          */
1050         protected function getServerUUID() {
1051                 return $this->srvCache->getWithSetCallback(
1052                         $this->srvCache->makeGlobalKey( 'mysql-server-uuid', $this->getServer() ),
1053                         self::SERVER_ID_CACHE_TTL,
1054                         function () {
1055                                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'server_uuid'" );
1056                                 $row = $this->fetchObject( $res );
1057
1058                                 return $row ? $row->Value : null;
1059                         }
1060                 );
1061         }
1062
1063         /**
1064          * @param string $fname
1065          * @return string[]
1066          */
1067         protected function getServerGTIDs( $fname = __METHOD__ ) {
1068                 $map = [];
1069                 // Get global-only variables like gtid_executed
1070                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'gtid_%'", $fname );
1071                 foreach ( $res as $row ) {
1072                         $map[$row->Variable_name] = $row->Value;
1073                 }
1074                 // Get session-specific (e.g. gtid_domain_id since that is were writes will log)
1075                 $res = $this->query( "SHOW SESSION VARIABLES LIKE 'gtid_%'", $fname );
1076                 foreach ( $res as $row ) {
1077                         $map[$row->Variable_name] = $row->Value;
1078                 }
1079
1080                 return $map;
1081         }
1082
1083         /**
1084          * @param string $role One of "MASTER"/"SLAVE"
1085          * @param string $fname
1086          * @return string[] Latest available server status row
1087          */
1088         protected function getServerRoleStatus( $role, $fname = __METHOD__ ) {
1089                 return $this->query( "SHOW $role STATUS", $fname )->fetchRow() ?: [];
1090         }
1091
1092         public function serverIsReadOnly() {
1093                 $res = $this->query( "SHOW GLOBAL VARIABLES LIKE 'read_only'", __METHOD__ );
1094                 $row = $this->fetchObject( $res );
1095
1096                 return $row ? ( strtolower( $row->Value ) === 'on' ) : false;
1097         }
1098
1099         /**
1100          * @param string $index
1101          * @return string
1102          */
1103         function useIndexClause( $index ) {
1104                 return "FORCE INDEX (" . $this->indexName( $index ) . ")";
1105         }
1106
1107         /**
1108          * @param string $index
1109          * @return string
1110          */
1111         function ignoreIndexClause( $index ) {
1112                 return "IGNORE INDEX (" . $this->indexName( $index ) . ")";
1113         }
1114
1115         /**
1116          * @return string
1117          */
1118         function lowPriorityOption() {
1119                 return 'LOW_PRIORITY';
1120         }
1121
1122         /**
1123          * @return string
1124          */
1125         public function getSoftwareLink() {
1126                 // MariaDB includes its name in its version string; this is how MariaDB's version of
1127                 // the mysql command-line client identifies MariaDB servers (see mariadb_connection()
1128                 // in libmysql/libmysql.c).
1129                 $version = $this->getServerVersion();
1130                 if ( strpos( $version, 'MariaDB' ) !== false || strpos( $version, '-maria-' ) !== false ) {
1131                         return '[{{int:version-db-mariadb-url}} MariaDB]';
1132                 }
1133
1134                 // Percona Server's version suffix is not very distinctive, and @@version_comment
1135                 // doesn't give the necessary info for source builds, so assume the server is MySQL.
1136                 // (Even Percona's version of mysql doesn't try to make the distinction.)
1137                 return '[{{int:version-db-mysql-url}} MySQL]';
1138         }
1139
1140         /**
1141          * @return string
1142          */
1143         public function getServerVersion() {
1144                 // Not using mysql_get_server_info() or similar for consistency: in the handshake,
1145                 // MariaDB 10 adds the prefix "5.5.5-", and only some newer client libraries strip
1146                 // it off (see RPL_VERSION_HACK in include/mysql_com.h).
1147                 if ( $this->serverVersion === null ) {
1148                         $this->serverVersion = $this->selectField( '', 'VERSION()', '', __METHOD__ );
1149                 }
1150                 return $this->serverVersion;
1151         }
1152
1153         /**
1154          * @param array $options
1155          */
1156         public function setSessionOptions( array $options ) {
1157                 if ( isset( $options['connTimeout'] ) ) {
1158                         $timeout = (int)$options['connTimeout'];
1159                         $this->query( "SET net_read_timeout=$timeout" );
1160                         $this->query( "SET net_write_timeout=$timeout" );
1161                 }
1162         }
1163
1164         /**
1165          * @param string &$sql
1166          * @param string &$newLine
1167          * @return bool
1168          */
1169         public function streamStatementEnd( &$sql, &$newLine ) {
1170                 if ( strtoupper( substr( $newLine, 0, 9 ) ) == 'DELIMITER' ) {
1171                         preg_match( '/^DELIMITER\s+(\S+)/', $newLine, $m );
1172                         $this->delimiter = $m[1];
1173                         $newLine = '';
1174                 }
1175
1176                 return parent::streamStatementEnd( $sql, $newLine );
1177         }
1178
1179         /**
1180          * Check to see if a named lock is available. This is non-blocking.
1181          *
1182          * @param string $lockName Name of lock to poll
1183          * @param string $method Name of method calling us
1184          * @return bool
1185          * @since 1.20
1186          */
1187         public function lockIsFree( $lockName, $method ) {
1188                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1189                         return false; // already held
1190                 }
1191
1192                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1193                 $result = $this->query( "SELECT IS_FREE_LOCK($encName) AS lockstatus", $method );
1194                 $row = $this->fetchObject( $result );
1195
1196                 return ( $row->lockstatus == 1 );
1197         }
1198
1199         /**
1200          * @param string $lockName
1201          * @param string $method
1202          * @param int $timeout
1203          * @return bool
1204          */
1205         public function lock( $lockName, $method, $timeout = 5 ) {
1206                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1207                 $result = $this->query( "SELECT GET_LOCK($encName, $timeout) AS lockstatus", $method );
1208                 $row = $this->fetchObject( $result );
1209
1210                 if ( $row->lockstatus == 1 ) {
1211                         parent::lock( $lockName, $method, $timeout ); // record
1212                         return true;
1213                 }
1214
1215                 $this->queryLogger->info( __METHOD__ . " failed to acquire lock '{lockname}'",
1216                         [ 'lockname' => $lockName ] );
1217
1218                 return false;
1219         }
1220
1221         /**
1222          * FROM MYSQL DOCS:
1223          * https://dev.mysql.com/doc/refman/5.0/en/miscellaneous-functions.html#function_release-lock
1224          * @param string $lockName
1225          * @param string $method
1226          * @return bool
1227          */
1228         public function unlock( $lockName, $method ) {
1229                 $encName = $this->addQuotes( $this->makeLockName( $lockName ) );
1230                 $result = $this->query( "SELECT RELEASE_LOCK($encName) as lockstatus", $method );
1231                 $row = $this->fetchObject( $result );
1232
1233                 if ( $row->lockstatus == 1 ) {
1234                         parent::unlock( $lockName, $method ); // record
1235                         return true;
1236                 }
1237
1238                 $this->queryLogger->warning( __METHOD__ . " failed to release lock '$lockName'\n" );
1239
1240                 return false;
1241         }
1242
1243         private function makeLockName( $lockName ) {
1244                 // https://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_get-lock
1245                 // Newer version enforce a 64 char length limit.
1246                 return ( strlen( $lockName ) > 64 ) ? sha1( $lockName ) : $lockName;
1247         }
1248
1249         public function namedLocksEnqueue() {
1250                 return true;
1251         }
1252
1253         public function tableLocksHaveTransactionScope() {
1254                 return false; // tied to TCP connection
1255         }
1256
1257         protected function doLockTables( array $read, array $write, $method ) {
1258                 $items = [];
1259                 foreach ( $write as $table ) {
1260                         $items[] = $this->tableName( $table ) . ' WRITE';
1261                 }
1262                 foreach ( $read as $table ) {
1263                         $items[] = $this->tableName( $table ) . ' READ';
1264                 }
1265
1266                 $sql = "LOCK TABLES " . implode( ',', $items );
1267                 $this->query( $sql, $method );
1268
1269                 return true;
1270         }
1271
1272         protected function doUnlockTables( $method ) {
1273                 $this->query( "UNLOCK TABLES", $method );
1274
1275                 return true;
1276         }
1277
1278         /**
1279          * @param bool $value
1280          */
1281         public function setBigSelects( $value = true ) {
1282                 if ( $value === 'default' ) {
1283                         if ( $this->defaultBigSelects === null ) {
1284                                 # Function hasn't been called before so it must already be set to the default
1285                                 return;
1286                         } else {
1287                                 $value = $this->defaultBigSelects;
1288                         }
1289                 } elseif ( $this->defaultBigSelects === null ) {
1290                         $this->defaultBigSelects =
1291                                 (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
1292                 }
1293                 $encValue = $value ? '1' : '0';
1294                 $this->query( "SET sql_big_selects=$encValue", __METHOD__ );
1295         }
1296
1297         /**
1298          * DELETE where the condition is a join. MySql uses multi-table deletes.
1299          * @param string $delTable
1300          * @param string $joinTable
1301          * @param string $delVar
1302          * @param string $joinVar
1303          * @param array|string $conds
1304          * @param bool|string $fname
1305          * @throws DBUnexpectedError
1306          */
1307         public function deleteJoin(
1308                 $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
1309         ) {
1310                 if ( !$conds ) {
1311                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with empty $conds' );
1312                 }
1313
1314                 $delTable = $this->tableName( $delTable );
1315                 $joinTable = $this->tableName( $joinTable );
1316                 $sql = "DELETE $delTable FROM $delTable, $joinTable WHERE $delVar=$joinVar ";
1317
1318                 if ( $conds != '*' ) {
1319                         $sql .= ' AND ' . $this->makeList( $conds, self::LIST_AND );
1320                 }
1321
1322                 $this->query( $sql, $fname );
1323         }
1324
1325         public function upsert(
1326                 $table, array $rows, $uniqueIndexes, array $set, $fname = __METHOD__
1327         ) {
1328                 if ( $rows === [] ) {
1329                         return true; // nothing to do
1330                 }
1331
1332                 if ( !is_array( reset( $rows ) ) ) {
1333                         $rows = [ $rows ];
1334                 }
1335
1336                 $table = $this->tableName( $table );
1337                 $columns = array_keys( $rows[0] );
1338
1339                 $sql = "INSERT INTO $table (" . implode( ',', $columns ) . ') VALUES ';
1340                 $rowTuples = [];
1341                 foreach ( $rows as $row ) {
1342                         $rowTuples[] = '(' . $this->makeList( $row ) . ')';
1343                 }
1344                 $sql .= implode( ',', $rowTuples );
1345                 $sql .= " ON DUPLICATE KEY UPDATE " . $this->makeList( $set, self::LIST_SET );
1346
1347                 $this->query( $sql, $fname );
1348
1349                 return true;
1350         }
1351
1352         /**
1353          * Determines how long the server has been up
1354          *
1355          * @return int
1356          */
1357         public function getServerUptime() {
1358                 $vars = $this->getMysqlStatus( 'Uptime' );
1359
1360                 return (int)$vars['Uptime'];
1361         }
1362
1363         /**
1364          * Determines if the last failure was due to a deadlock
1365          *
1366          * @return bool
1367          */
1368         public function wasDeadlock() {
1369                 return $this->lastErrno() == 1213;
1370         }
1371
1372         /**
1373          * Determines if the last failure was due to a lock timeout
1374          *
1375          * @return bool
1376          */
1377         public function wasLockTimeout() {
1378                 return $this->lastErrno() == 1205;
1379         }
1380
1381         /**
1382          * Determines if the last failure was due to the database being read-only.
1383          *
1384          * @return bool
1385          */
1386         public function wasReadOnlyError() {
1387                 return $this->lastErrno() == 1223 ||
1388                         ( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
1389         }
1390
1391         public function wasConnectionError( $errno ) {
1392                 return $errno == 2013 || $errno == 2006;
1393         }
1394
1395         protected function wasKnownStatementRollbackError() {
1396                 $errno = $this->lastErrno();
1397
1398                 if ( $errno === 1205 ) { // lock wait timeout
1399                         // Note that this is uncached to avoid stale values of SET is used
1400                         $row = $this->selectRow(
1401                                 false,
1402                                 [ 'innodb_rollback_on_timeout' => '@@innodb_rollback_on_timeout' ],
1403                                 [],
1404                                 __METHOD__
1405                         );
1406                         // https://dev.mysql.com/doc/refman/5.7/en/innodb-error-handling.html
1407                         // https://dev.mysql.com/doc/refman/5.5/en/innodb-parameters.html
1408                         return $row->innodb_rollback_on_timeout ? false : true;
1409                 }
1410
1411                 // See https://dev.mysql.com/doc/refman/5.5/en/error-messages-server.html
1412                 return in_array( $errno, [ 1022, 1062, 1216, 1217, 1137, 1146, 1051, 1054 ], true );
1413         }
1414
1415         /**
1416          * @param string $oldName
1417          * @param string $newName
1418          * @param bool $temporary
1419          * @param string $fname
1420          * @return bool
1421          */
1422         public function duplicateTableStructure(
1423                 $oldName, $newName, $temporary = false, $fname = __METHOD__
1424         ) {
1425                 $tmp = $temporary ? 'TEMPORARY ' : '';
1426                 $newName = $this->addIdentifierQuotes( $newName );
1427                 $oldName = $this->addIdentifierQuotes( $oldName );
1428                 $query = "CREATE $tmp TABLE $newName (LIKE $oldName)";
1429
1430                 return $this->query( $query, $fname );
1431         }
1432
1433         /**
1434          * List all tables on the database
1435          *
1436          * @param string|null $prefix Only show tables with this prefix, e.g. mw_
1437          * @param string $fname Calling function name
1438          * @return array
1439          */
1440         public function listTables( $prefix = null, $fname = __METHOD__ ) {
1441                 $result = $this->query( "SHOW TABLES", $fname );
1442
1443                 $endArray = [];
1444
1445                 foreach ( $result as $table ) {
1446                         $vars = get_object_vars( $table );
1447                         $table = array_pop( $vars );
1448
1449                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1450                                 $endArray[] = $table;
1451                         }
1452                 }
1453
1454                 return $endArray;
1455         }
1456
1457         /**
1458          * @param string $tableName
1459          * @param string $fName
1460          * @return bool|ResultWrapper
1461          */
1462         public function dropTable( $tableName, $fName = __METHOD__ ) {
1463                 if ( !$this->tableExists( $tableName, $fName ) ) {
1464                         return false;
1465                 }
1466
1467                 return $this->query( "DROP TABLE IF EXISTS " . $this->tableName( $tableName ), $fName );
1468         }
1469
1470         /**
1471          * Get status information from SHOW STATUS in an associative array
1472          *
1473          * @param string $which
1474          * @return array
1475          */
1476         private function getMysqlStatus( $which = "%" ) {
1477                 $res = $this->query( "SHOW STATUS LIKE '{$which}'" );
1478                 $status = [];
1479
1480                 foreach ( $res as $row ) {
1481                         $status[$row->Variable_name] = $row->Value;
1482                 }
1483
1484                 return $status;
1485         }
1486
1487         /**
1488          * Lists VIEWs in the database
1489          *
1490          * @param string|null $prefix Only show VIEWs with this prefix, eg.
1491          * unit_test_, or $wgDBprefix. Default: null, would return all views.
1492          * @param string $fname Name of calling function
1493          * @return array
1494          * @since 1.22
1495          */
1496         public function listViews( $prefix = null, $fname = __METHOD__ ) {
1497                 // The name of the column containing the name of the VIEW
1498                 $propertyName = 'Tables_in_' . $this->getDBname();
1499
1500                 // Query for the VIEWS
1501                 $res = $this->query( 'SHOW FULL TABLES WHERE TABLE_TYPE = "VIEW"' );
1502                 $allViews = [];
1503                 foreach ( $res as $row ) {
1504                         array_push( $allViews, $row->$propertyName );
1505                 }
1506
1507                 if ( is_null( $prefix ) || $prefix === '' ) {
1508                         return $allViews;
1509                 }
1510
1511                 $filteredViews = [];
1512                 foreach ( $allViews as $viewName ) {
1513                         // Does the name of this VIEW start with the table-prefix?
1514                         if ( strpos( $viewName, $prefix ) === 0 ) {
1515                                 array_push( $filteredViews, $viewName );
1516                         }
1517                 }
1518
1519                 return $filteredViews;
1520         }
1521
1522         /**
1523          * Differentiates between a TABLE and a VIEW.
1524          *
1525          * @param string $name Name of the TABLE/VIEW to test
1526          * @param string|null $prefix
1527          * @return bool
1528          * @since 1.22
1529          */
1530         public function isView( $name, $prefix = null ) {
1531                 return in_array( $name, $this->listViews( $prefix ) );
1532         }
1533
1534         protected function isTransactableQuery( $sql ) {
1535                 return parent::isTransactableQuery( $sql ) &&
1536                         !preg_match( '/^SELECT\s+(GET|RELEASE|IS_FREE)_LOCK\(/', $sql );
1537         }
1538
1539         public function buildStringCast( $field ) {
1540                 return "CAST( $field AS BINARY )";
1541         }
1542
1543         /**
1544          * @param string $field Field or column to cast
1545          * @return string
1546          */
1547         public function buildIntegerCast( $field ) {
1548                 return 'CAST( ' . $field . ' AS SIGNED )';
1549         }
1550
1551         /*
1552          * @return bool Whether GTID support is used (mockable for testing)
1553          */
1554         protected function useGTIDs() {
1555                 return $this->useGTIDs;
1556         }
1557 }
1558
1559 /**
1560  * @deprecated since 1.29
1561  */
1562 class_alias( DatabaseMysqlBase::class, 'DatabaseMysqlBase' );