includes/libs/rdbms/database/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres 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 use Wikimedia\WaitConditionLoop;
  24
  25 /**
  26  * @ingroup Database
  27  */
  28 class DatabasePostgres extends Database {
  29         /** @var int|bool */
  30         protected $port;
  31
  32         /** @var resource */
  33         protected $mLastResult = null;
  34         /** @var int The number of rows affected as an integer */
  35         protected $mAffectedRows = null;
  36
  37         /** @var int */
  38         private $mInsertId = null;
  39         /** @var float|string */
  40         private $numericVersion = null;
  41         /** @var string Connect string to open a PostgreSQL connection */
  42         private $connectString;
  43         /** @var string */
  44         private $mCoreSchema;
  45         /** @var string[] Map of (reserved table name => alternate table name) */
  46         private $keywordTableMap = [];
  47
  48         /**
  49          * @see Database::__construct()
  50          * @param array $params Additional parameters include:
  51          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  52          */
  53         public function __construct( array $params ) {
  54                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  55                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  56                         ? $params['keywordTableMap']
  57                         : [];
  58
  59                 parent::__construct( $params );
  60         }
  61
  62         public function getType() {
  63                 return 'postgres';
  64         }
  65
  66         public function implicitGroupby() {
  67                 return false;
  68         }
  69
  70         public function implicitOrderby() {
  71                 return false;
  72         }
  73
  74         public function hasConstraint( $name ) {
  75                 $conn = $this->getBindingHandle();
  76
  77                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  78                         "WHERE c.connamespace = n.oid AND conname = '" .
  79                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  80                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  81                 $res = $this->doQuery( $sql );
  82
  83                 return $this->numRows( $res );
  84         }
  85
  86         public function open( $server, $user, $password, $dbName ) {
  87                 # Test for Postgres support, to avoid suppressed fatal error
  88                 if ( !function_exists( 'pg_connect' ) ) {
  89                         throw new DBConnectionError(
  90                                 $this,
  91                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  92                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  93                                 "webserver and database)\n"
  94                         );
  95                 }
  96
  97                 $this->mServer = $server;
  98                 $this->mUser = $user;
  99                 $this->mPassword = $password;
 100                 $this->mDBname = $dbName;
 101
 102                 $connectVars = [
 103                         'dbname' => $dbName,
 104                         'user' => $user,
 105                         'password' => $password
 106                 ];
 107                 if ( $server != false && $server != '' ) {
 108                         $connectVars['host'] = $server;
 109                 }
 110                 if ( (int)$this->port > 0 ) {
 111                         $connectVars['port'] = (int)$this->port;
 112                 }
 113                 if ( $this->mFlags & self::DBO_SSL ) {
 114                         $connectVars['sslmode'] = 1;
 115                 }
 116
 117                 $this->connectString = $this->makeConnectionString( $connectVars );
 118                 $this->close();
 119                 $this->installErrorHandler();
 120
 121                 try {
 122                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 123                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 124                 } catch ( Exception $ex ) {
 125                         $this->restoreErrorHandler();
 126                         throw $ex;
 127                 }
 128
 129                 $phpError = $this->restoreErrorHandler();
 130
 131                 if ( !$this->mConn ) {
 132                         $this->queryLogger->debug(
 133                                 "DB connection error\n" .
 134                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 135                                 substr( $password, 0, 3 ) . "...\n"
 136                         );
 137                         $this->queryLogger->debug( $this->lastError() . "\n" );
 138                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 139                 }
 140
 141                 $this->mOpened = true;
 142
 143                 # If called from the command-line (e.g. importDump), only show errors
 144                 if ( $this->cliMode ) {
 145                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 146                 }
 147
 148                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 149                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 150                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 151                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 152                 if ( $this->getServerVersion() >= 9.0 ) {
 153                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 154                 }
 155
 156                 $this->determineCoreSchema( $this->mSchema );
 157                 // The schema to be used is now in the search path; no need for explicit qualification
 158                 $this->mSchema = '';
 159
 160                 return $this->mConn;
 161         }
 162
 163         /**
 164          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 165          * DB name doesn't match the open connection, open a new one
 166          * @param string $db
 167          * @return bool
 168          */
 169         public function selectDB( $db ) {
 170                 if ( $this->mDBname !== $db ) {
 171                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 172                 } else {
 173                         return true;
 174                 }
 175         }
 176
 177         /**
 178          * @param string[] $vars
 179          * @return string
 180          */
 181         private function makeConnectionString( $vars ) {
 182                 $s = '';
 183                 foreach ( $vars as $name => $value ) {
 184                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 185                 }
 186
 187                 return $s;
 188         }
 189
 190         protected function closeConnection() {
 191                 return $this->mConn ? pg_close( $this->mConn ) : true;
 192         }
 193
 194         public function doQuery( $sql ) {
 195                 $conn = $this->getBindingHandle();
 196
 197                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 198                 // Clear previously left over PQresult
 199                 while ( $res = pg_get_result( $conn ) ) {
 200                         pg_free_result( $res );
 201                 }
 202                 if ( pg_send_query( $conn, $sql ) === false ) {
 203                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 204                 }
 205                 $this->mLastResult = pg_get_result( $conn );
 206                 $this->mAffectedRows = null;
 207                 if ( pg_result_error( $this->mLastResult ) ) {
 208                         return false;
 209                 }
 210
 211                 return $this->mLastResult;
 212         }
 213
 214         protected function dumpError() {
 215                 $diags = [
 216                         PGSQL_DIAG_SEVERITY,
 217                         PGSQL_DIAG_SQLSTATE,
 218                         PGSQL_DIAG_MESSAGE_PRIMARY,
 219                         PGSQL_DIAG_MESSAGE_DETAIL,
 220                         PGSQL_DIAG_MESSAGE_HINT,
 221                         PGSQL_DIAG_STATEMENT_POSITION,
 222                         PGSQL_DIAG_INTERNAL_POSITION,
 223                         PGSQL_DIAG_INTERNAL_QUERY,
 224                         PGSQL_DIAG_CONTEXT,
 225                         PGSQL_DIAG_SOURCE_FILE,
 226                         PGSQL_DIAG_SOURCE_LINE,
 227                         PGSQL_DIAG_SOURCE_FUNCTION
 228                 ];
 229                 foreach ( $diags as $d ) {
 230                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 231                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 232                 }
 233         }
 234
 235         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 236                 if ( $tempIgnore ) {
 237                         /* Check for constraint violation */
 238                         if ( $errno === '23505' ) {
 239                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 240
 241                                 return;
 242                         }
 243                 }
 244                 /* Transaction stays in the ERROR state until rolled back */
 245                 if ( $this->mTrxLevel ) {
 246                         $ignore = $this->ignoreErrors( true );
 247                         $this->rollback( __METHOD__ );
 248                         $this->ignoreErrors( $ignore );
 249                 }
 250                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 251         }
 252
 253         public function freeResult( $res ) {
 254                 if ( $res instanceof ResultWrapper ) {
 255                         $res = $res->result;
 256                 }
 257                 MediaWiki\suppressWarnings();
 258                 $ok = pg_free_result( $res );
 259                 MediaWiki\restoreWarnings();
 260                 if ( !$ok ) {
 261                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 262                 }
 263         }
 264
 265         public function fetchObject( $res ) {
 266                 if ( $res instanceof ResultWrapper ) {
 267                         $res = $res->result;
 268                 }
 269                 MediaWiki\suppressWarnings();
 270                 $row = pg_fetch_object( $res );
 271                 MediaWiki\restoreWarnings();
 272                 # @todo FIXME: HACK HACK HACK HACK debug
 273
 274                 # @todo hashar: not sure if the following test really trigger if the object
 275                 #          fetching failed.
 276                 $conn = $this->getBindingHandle();
 277                 if ( pg_last_error( $conn ) ) {
 278                         throw new DBUnexpectedError(
 279                                 $this,
 280                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 281                         );
 282                 }
 283
 284                 return $row;
 285         }
 286
 287         public function fetchRow( $res ) {
 288                 if ( $res instanceof ResultWrapper ) {
 289                         $res = $res->result;
 290                 }
 291                 MediaWiki\suppressWarnings();
 292                 $row = pg_fetch_array( $res );
 293                 MediaWiki\restoreWarnings();
 294
 295                 $conn = $this->getBindingHandle();
 296                 if ( pg_last_error( $conn ) ) {
 297                         throw new DBUnexpectedError(
 298                                 $this,
 299                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 300                         );
 301                 }
 302
 303                 return $row;
 304         }
 305
 306         public function numRows( $res ) {
 307                 if ( $res instanceof ResultWrapper ) {
 308                         $res = $res->result;
 309                 }
 310                 MediaWiki\suppressWarnings();
 311                 $n = pg_num_rows( $res );
 312                 MediaWiki\restoreWarnings();
 313
 314                 $conn = $this->getBindingHandle();
 315                 if ( pg_last_error( $conn ) ) {
 316                         throw new DBUnexpectedError(
 317                                 $this,
 318                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 319                         );
 320                 }
 321
 322                 return $n;
 323         }
 324
 325         public function numFields( $res ) {
 326                 if ( $res instanceof ResultWrapper ) {
 327                         $res = $res->result;
 328                 }
 329
 330                 return pg_num_fields( $res );
 331         }
 332
 333         public function fieldName( $res, $n ) {
 334                 if ( $res instanceof ResultWrapper ) {
 335                         $res = $res->result;
 336                 }
 337
 338                 return pg_field_name( $res, $n );
 339         }
 340
 341         /**
 342          * Return the result of the last call to nextSequenceValue();
 343          * This must be called after nextSequenceValue().
 344          *
 345          * @return int|null
 346          */
 347         public function insertId() {
 348                 return $this->mInsertId;
 349         }
 350
 351         public function dataSeek( $res, $row ) {
 352                 if ( $res instanceof ResultWrapper ) {
 353                         $res = $res->result;
 354                 }
 355
 356                 return pg_result_seek( $res, $row );
 357         }
 358
 359         public function lastError() {
 360                 if ( $this->mConn ) {
 361                         if ( $this->mLastResult ) {
 362                                 return pg_result_error( $this->mLastResult );
 363                         } else {
 364                                 return pg_last_error();
 365                         }
 366                 }
 367
 368                 return $this->getLastPHPError() ?: 'No database connection';
 369         }
 370
 371         public function lastErrno() {
 372                 if ( $this->mLastResult ) {
 373                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 374                 } else {
 375                         return false;
 376                 }
 377         }
 378
 379         public function affectedRows() {
 380                 if ( !is_null( $this->mAffectedRows ) ) {
 381                         // Forced result for simulated queries
 382                         return $this->mAffectedRows;
 383                 }
 384                 if ( empty( $this->mLastResult ) ) {
 385                         return 0;
 386                 }
 387
 388                 return pg_affected_rows( $this->mLastResult );
 389         }
 390
 391         /**
 392          * Estimate rows in dataset
 393          * Returns estimated count, based on EXPLAIN output
 394          * This is not necessarily an accurate estimate, so use sparingly
 395          * Returns -1 if count cannot be found
 396          * Takes same arguments as Database::select()
 397          *
 398          * @param string $table
 399          * @param string $vars
 400          * @param string $conds
 401          * @param string $fname
 402          * @param array $options
 403          * @return int
 404          */
 405         public function estimateRowCount( $table, $vars = '*', $conds = '',
 406                 $fname = __METHOD__, $options = []
 407         ) {
 408                 $options['EXPLAIN'] = true;
 409                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 410                 $rows = -1;
 411                 if ( $res ) {
 412                         $row = $this->fetchRow( $res );
 413                         $count = [];
 414                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 415                                 $rows = (int)$count[1];
 416                         }
 417                 }
 418
 419                 return $rows;
 420         }
 421
 422         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 423                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 424                 $res = $this->query( $sql, $fname );
 425                 if ( !$res ) {
 426                         return null;
 427                 }
 428                 foreach ( $res as $row ) {
 429                         if ( $row->indexname == $this->indexName( $index ) ) {
 430                                 return $row;
 431                         }
 432                 }
 433
 434                 return false;
 435         }
 436
 437         public function indexAttributes( $index, $schema = false ) {
 438                 if ( $schema === false ) {
 439                         $schema = $this->getCoreSchema();
 440                 }
 441                 /*
 442                  * A subquery would be not needed if we didn't care about the order
 443                  * of attributes, but we do
 444                  */
 445                 $sql = <<<__INDEXATTR__
 446
 447                         SELECT opcname,
 448                                 attname,
 449                                 i.indoption[s.g] as option,
 450                                 pg_am.amname
 451                         FROM
 452                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 453                                         FROM
 454                                                 pg_index isub
 455                                         JOIN pg_class cis
 456                                                 ON cis.oid=isub.indexrelid
 457                                         JOIN pg_namespace ns
 458                                                 ON cis.relnamespace = ns.oid
 459                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 460                                 pg_attribute,
 461                                 pg_opclass opcls,
 462                                 pg_am,
 463                                 pg_class ci
 464                                 JOIN pg_index i
 465                                         ON ci.oid=i.indexrelid
 466                                 JOIN pg_class ct
 467                                         ON ct.oid = i.indrelid
 468                                 JOIN pg_namespace n
 469                                         ON ci.relnamespace = n.oid
 470                                 WHERE
 471                                         ci.relname='$index' AND n.nspname='$schema'
 472                                         AND     attrelid = ct.oid
 473                                         AND     i.indkey[s.g] = attnum
 474                                         AND     i.indclass[s.g] = opcls.oid
 475                                         AND     pg_am.oid = opcls.opcmethod
 476 __INDEXATTR__;
 477                 $res = $this->query( $sql, __METHOD__ );
 478                 $a = [];
 479                 if ( $res ) {
 480                         foreach ( $res as $row ) {
 481                                 $a[] = [
 482                                         $row->attname,
 483                                         $row->opcname,
 484                                         $row->amname,
 485                                         $row->option ];
 486                         }
 487                 } else {
 488                         return null;
 489                 }
 490
 491                 return $a;
 492         }
 493
 494         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 495                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 496                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 497                         $this->strencode( $this->indexName( $index ) ) .
 498                         ")'";
 499                 $res = $this->query( $sql, $fname );
 500                 if ( !$res ) {
 501                         return null;
 502                 }
 503
 504                 return $res->numRows() > 0;
 505         }
 506
 507         public function selectSQLText(
 508                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 509         ) {
 510                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 511                 // to the parent function to get the actual SQL text.
 512                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 513                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 514                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 515                 // accordingly.
 516                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 517                 if ( is_array( $options ) ) {
 518                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 519                         if ( $forUpdateKey !== false && $join_conds ) {
 520                                 unset( $options[$forUpdateKey] );
 521
 522                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 523                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 524                                                 $options['FOR UPDATE'][] = $table_cond;
 525                                         }
 526                                 }
 527                         }
 528
 529                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 530                                 unset( $options['ORDER BY'] );
 531                         }
 532                 }
 533
 534                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 535         }
 536
 537         /**
 538          * INSERT wrapper, inserts an array into a table
 539          *
 540          * $args may be a single associative array, or an array of these with numeric keys,
 541          * for multi-row insert (Postgres version 8.2 and above only).
 542          *
 543          * @param string $table Name of the table to insert to.
 544          * @param array $args Items to insert into the table.
 545          * @param string $fname Name of the function, for profiling
 546          * @param array|string $options String or array. Valid options: IGNORE
 547          * @return bool Success of insert operation. IGNORE always returns true.
 548          */
 549         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 550                 if ( !count( $args ) ) {
 551                         return true;
 552                 }
 553
 554                 $table = $this->tableName( $table );
 555                 if ( !isset( $this->numericVersion ) ) {
 556                         $this->getServerVersion();
 557                 }
 558
 559                 if ( !is_array( $options ) ) {
 560                         $options = [ $options ];
 561                 }
 562
 563                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 564                         $multi = true;
 565                         $keys = array_keys( $args[0] );
 566                 } else {
 567                         $multi = false;
 568                         $keys = array_keys( $args );
 569                 }
 570
 571                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 572                 $savepoint = $olde = null;
 573                 $numrowsinserted = 0;
 574                 if ( in_array( 'IGNORE', $options ) ) {
 575                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 576                         $olde = error_reporting( 0 );
 577                         // For future use, we may want to track the number of actual inserts
 578                         // Right now, insert (all writes) simply return true/false
 579                 }
 580
 581                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 582
 583                 if ( $multi ) {
 584                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 585                                 $first = true;
 586                                 foreach ( $args as $row ) {
 587                                         if ( $first ) {
 588                                                 $first = false;
 589                                         } else {
 590                                                 $sql .= ',';
 591                                         }
 592                                         $sql .= '(' . $this->makeList( $row ) . ')';
 593                                 }
 594                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 595                         } else {
 596                                 $res = true;
 597                                 $origsql = $sql;
 598                                 foreach ( $args as $row ) {
 599                                         $tempsql = $origsql;
 600                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 601
 602                                         if ( $savepoint ) {
 603                                                 $savepoint->savepoint();
 604                                         }
 605
 606                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 607
 608                                         if ( $savepoint ) {
 609                                                 $bar = pg_result_error( $this->mLastResult );
 610                                                 if ( $bar != false ) {
 611                                                         $savepoint->rollback();
 612                                                 } else {
 613                                                         $savepoint->release();
 614                                                         $numrowsinserted++;
 615                                                 }
 616                                         }
 617
 618                                         // If any of them fail, we fail overall for this function call
 619                                         // Note that this will be ignored if IGNORE is set
 620                                         if ( !$tempres ) {
 621                                                 $res = false;
 622                                         }
 623                                 }
 624                         }
 625                 } else {
 626                         // Not multi, just a lone insert
 627                         if ( $savepoint ) {
 628                                 $savepoint->savepoint();
 629                         }
 630
 631                         $sql .= '(' . $this->makeList( $args ) . ')';
 632                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 633                         if ( $savepoint ) {
 634                                 $bar = pg_result_error( $this->mLastResult );
 635                                 if ( $bar != false ) {
 636                                         $savepoint->rollback();
 637                                 } else {
 638                                         $savepoint->release();
 639                                         $numrowsinserted++;
 640                                 }
 641                         }
 642                 }
 643                 if ( $savepoint ) {
 644                         error_reporting( $olde );
 645                         $savepoint->commit();
 646
 647                         // Set the affected row count for the whole operation
 648                         $this->mAffectedRows = $numrowsinserted;
 649
 650                         // IGNORE always returns true
 651                         return true;
 652                 }
 653
 654                 return $res;
 655         }
 656
 657         /**
 658          * INSERT SELECT wrapper
 659          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 660          * Source items may be literals rather then field names, but strings should
 661          * be quoted with Database::addQuotes()
 662          * $conds may be "*" to copy the whole table
 663          * srcTable may be an array of tables.
 664          * @todo FIXME: Implement this a little better (seperate select/insert)?
 665          *
 666          * @param string $destTable
 667          * @param array|string $srcTable
 668          * @param array $varMap
 669          * @param array $conds
 670          * @param string $fname
 671          * @param array $insertOptions
 672          * @param array $selectOptions
 673          * @return bool
 674          */
 675         public function nativeInsertSelect(
 676                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 677                 $insertOptions = [], $selectOptions = []
 678         ) {
 679                 $destTable = $this->tableName( $destTable );
 680
 681                 if ( !is_array( $insertOptions ) ) {
 682                         $insertOptions = [ $insertOptions ];
 683                 }
 684
 685                 /*
 686                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 687                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 688                  */
 689                 $savepoint = $olde = null;
 690                 $numrowsinserted = 0;
 691                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 692                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 693                         $olde = error_reporting( 0 );
 694                         $savepoint->savepoint();
 695                 }
 696
 697                 if ( !is_array( $selectOptions ) ) {
 698                         $selectOptions = [ $selectOptions ];
 699                 }
 700                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 701                         $this->makeSelectOptions( $selectOptions );
 702                 if ( is_array( $srcTable ) ) {
 703                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 704                 } else {
 705                         $srcTable = $this->tableName( $srcTable );
 706                 }
 707
 708                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 709                         " SELECT $startOpts " . implode( ',', $varMap ) .
 710                         " FROM $srcTable $useIndex $ignoreIndex ";
 711
 712                 if ( $conds != '*' ) {
 713                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 714                 }
 715
 716                 $sql .= " $tailOpts";
 717
 718                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 719                 if ( $savepoint ) {
 720                         $bar = pg_result_error( $this->mLastResult );
 721                         if ( $bar != false ) {
 722                                 $savepoint->rollback();
 723                         } else {
 724                                 $savepoint->release();
 725                                 $numrowsinserted++;
 726                         }
 727                         error_reporting( $olde );
 728                         $savepoint->commit();
 729
 730                         // Set the affected row count for the whole operation
 731                         $this->mAffectedRows = $numrowsinserted;
 732
 733                         // IGNORE always returns true
 734                         return true;
 735                 }
 736
 737                 return $res;
 738         }
 739
 740         public function tableName( $name, $format = 'quoted' ) {
 741                 // Replace reserved words with better ones
 742                 $name = $this->remappedTableName( $name );
 743
 744                 return parent::tableName( $name, $format );
 745         }
 746
 747         /**
 748          * @param string $name
 749          * @return string Value of $name or remapped name if $name is a reserved keyword
 750          */
 751         public function remappedTableName( $name ) {
 752                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 753         }
 754
 755         /**
 756          * @param string $name
 757          * @param string $format
 758          * @return string Qualified and encoded (if requested) table name
 759          */
 760         public function realTableName( $name, $format = 'quoted' ) {
 761                 return parent::tableName( $name, $format );
 762         }
 763
 764         public function nextSequenceValue( $seqName ) {
 765                 $safeseq = str_replace( "'", "''", $seqName );
 766                 $res = $this->query( "SELECT nextval('$safeseq')" );
 767                 $row = $this->fetchRow( $res );
 768                 $this->mInsertId = $row[0];
 769
 770                 return $this->mInsertId;
 771         }
 772
 773         /**
 774          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 775          *
 776          * @param string $seqName
 777          * @return int
 778          */
 779         public function currentSequenceValue( $seqName ) {
 780                 $safeseq = str_replace( "'", "''", $seqName );
 781                 $res = $this->query( "SELECT currval('$safeseq')" );
 782                 $row = $this->fetchRow( $res );
 783                 $currval = $row[0];
 784
 785                 return $currval;
 786         }
 787
 788         public function textFieldSize( $table, $field ) {
 789                 $table = $this->tableName( $table );
 790                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 791                         FROM pg_class c, pg_attribute a, pg_type t
 792                         WHERE relname='$table' AND a.attrelid=c.oid AND
 793                                 a.atttypid=t.oid and a.attname='$field'";
 794                 $res = $this->query( $sql );
 795                 $row = $this->fetchObject( $res );
 796                 if ( $row->ftype == 'varchar' ) {
 797                         $size = $row->size - 4;
 798                 } else {
 799                         $size = $row->size;
 800                 }
 801
 802                 return $size;
 803         }
 804
 805         public function limitResult( $sql, $limit, $offset = false ) {
 806                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 807         }
 808
 809         public function wasDeadlock() {
 810                 return $this->lastErrno() == '40P01';
 811         }
 812
 813         public function duplicateTableStructure(
 814                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 815         ) {
 816                 $newName = $this->addIdentifierQuotes( $newName );
 817                 $oldName = $this->addIdentifierQuotes( $oldName );
 818
 819                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 820                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 821         }
 822
 823         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 824                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 825                 $result = $this->query(
 826                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 827                 $endArray = [];
 828
 829                 foreach ( $result as $table ) {
 830                         $vars = get_object_vars( $table );
 831                         $table = array_pop( $vars );
 832                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 833                                 $endArray[] = $table;
 834                         }
 835                 }
 836
 837                 return $endArray;
 838         }
 839
 840         public function timestamp( $ts = 0 ) {
 841                 $ct = new ConvertibleTimestamp( $ts );
 842
 843                 return $ct->getTimestamp( TS_POSTGRES );
 844         }
 845
 846         /**
 847          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 848          * to https://secure.php.net/manual/en/ref.pgsql.php
 849          *
 850          * Parsing a postgres array can be a tricky problem, he's my
 851          * take on this, it handles multi-dimensional arrays plus
 852          * escaping using a nasty regexp to determine the limits of each
 853          * data-item.
 854          *
 855          * This should really be handled by PHP PostgreSQL module
 856          *
 857          * @since 1.19
 858          * @param string $text Postgreql array returned in a text form like {a,b}
 859          * @param string $output
 860          * @param int|bool $limit
 861          * @param int $offset
 862          * @return string
 863          */
 864         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 865                 if ( false === $limit ) {
 866                         $limit = strlen( $text ) - 1;
 867                         $output = [];
 868                 }
 869                 if ( '{}' == $text ) {
 870                         return $output;
 871                 }
 872                 do {
 873                         if ( '{' != $text[$offset] ) {
 874                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 875                                         $text, $match, 0, $offset );
 876                                 $offset += strlen( $match[0] );
 877                                 $output[] = ( '"' != $match[1][0]
 878                                         ? $match[1]
 879                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 880                                 if ( '},' == $match[3] ) {
 881                                         return $output;
 882                                 }
 883                         } else {
 884                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 885                         }
 886                 } while ( $limit > $offset );
 887
 888                 return $output;
 889         }
 890
 891         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 892                 return $valuedata;
 893         }
 894
 895         public function getSoftwareLink() {
 896                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 897         }
 898
 899         /**
 900          * Return current schema (executes SELECT current_schema())
 901          * Needs transaction
 902          *
 903          * @since 1.19
 904          * @return string Default schema for the current session
 905          */
 906         public function getCurrentSchema() {
 907                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 908                 $row = $this->fetchRow( $res );
 909
 910                 return $row[0];
 911         }
 912
 913         /**
 914          * Return list of schemas which are accessible without schema name
 915          * This is list does not contain magic keywords like "$user"
 916          * Needs transaction
 917          *
 918          * @see getSearchPath()
 919          * @see setSearchPath()
 920          * @since 1.19
 921          * @return array List of actual schemas for the current sesson
 922          */
 923         public function getSchemas() {
 924                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 925                 $row = $this->fetchRow( $res );
 926                 $schemas = [];
 927
 928                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 929
 930                 return $this->pg_array_parse( $row[0], $schemas );
 931         }
 932
 933         /**
 934          * Return search patch for schemas
 935          * This is different from getSchemas() since it contain magic keywords
 936          * (like "$user").
 937          * Needs transaction
 938          *
 939          * @since 1.19
 940          * @return array How to search for table names schemas for the current user
 941          */
 942         public function getSearchPath() {
 943                 $res = $this->query( "SHOW search_path", __METHOD__ );
 944                 $row = $this->fetchRow( $res );
 945
 946                 /* PostgreSQL returns SHOW values as strings */
 947
 948                 return explode( ",", $row[0] );
 949         }
 950
 951         /**
 952          * Update search_path, values should already be sanitized
 953          * Values may contain magic keywords like "$user"
 954          * @since 1.19
 955          *
 956          * @param array $search_path List of schemas to be searched by default
 957          */
 958         private function setSearchPath( $search_path ) {
 959                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 960         }
 961
 962         /**
 963          * Determine default schema for the current application
 964          * Adjust this session schema search path if desired schema exists
 965          * and is not alread there.
 966          *
 967          * We need to have name of the core schema stored to be able
 968          * to query database metadata.
 969          *
 970          * This will be also called by the installer after the schema is created
 971          *
 972          * @since 1.19
 973          *
 974          * @param string $desiredSchema
 975          */
 976         public function determineCoreSchema( $desiredSchema ) {
 977                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 978                 if ( $this->schemaExists( $desiredSchema ) ) {
 979                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 980                                 $this->mCoreSchema = $desiredSchema;
 981                                 $this->queryLogger->debug(
 982                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 983                         } else {
 984                                 /**
 985                                  * Prepend our schema (e.g. 'mediawiki') in front
 986                                  * of the search path
 987                                  * Fixes bug 15816
 988                                  */
 989                                 $search_path = $this->getSearchPath();
 990                                 array_unshift( $search_path,
 991                                         $this->addIdentifierQuotes( $desiredSchema ) );
 992                                 $this->setSearchPath( $search_path );
 993                                 $this->mCoreSchema = $desiredSchema;
 994                                 $this->queryLogger->debug(
 995                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 996                         }
 997                 } else {
 998                         $this->mCoreSchema = $this->getCurrentSchema();
 999                         $this->queryLogger->debug(
1000                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1001                                 $this->mCoreSchema . "\"\n" );
1002                 }
1003                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1004                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1005         }
1006
1007         /**
1008          * Return schema name for core application tables
1009          *
1010          * @since 1.19
1011          * @return string Core schema name
1012          */
1013         public function getCoreSchema() {
1014                 return $this->mCoreSchema;
1015         }
1016
1017         public function getServerVersion() {
1018                 if ( !isset( $this->numericVersion ) ) {
1019                         $conn = $this->getBindingHandle();
1020                         $versionInfo = pg_version( $conn );
1021                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1022                                 // Old client, abort install
1023                                 $this->numericVersion = '7.3 or earlier';
1024                         } elseif ( isset( $versionInfo['server'] ) ) {
1025                                 // Normal client
1026                                 $this->numericVersion = $versionInfo['server'];
1027                         } else {
1028                                 // Bug 16937: broken pgsql extension from PHP<5.3
1029                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1030                         }
1031                 }
1032
1033                 return $this->numericVersion;
1034         }
1035
1036         /**
1037          * Query whether a given relation exists (in the given schema, or the
1038          * default mw one if not given)
1039          * @param string $table
1040          * @param array|string $types
1041          * @param bool|string $schema
1042          * @return bool
1043          */
1044         private function relationExists( $table, $types, $schema = false ) {
1045                 if ( !is_array( $types ) ) {
1046                         $types = [ $types ];
1047                 }
1048                 if ( $schema === false ) {
1049                         $schema = $this->getCoreSchema();
1050                 }
1051                 $etable = $this->addQuotes( $table );
1052                 $eschema = $this->addQuotes( $schema );
1053                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1054                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1055                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1056                 $res = $this->query( $sql );
1057                 $count = $res ? $res->numRows() : 0;
1058
1059                 return (bool)$count;
1060         }
1061
1062         /**
1063          * For backward compatibility, this function checks both tables and views.
1064          * @param string $table
1065          * @param string $fname
1066          * @param bool|string $schema
1067          * @return bool
1068          */
1069         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1070                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1071         }
1072
1073         public function sequenceExists( $sequence, $schema = false ) {
1074                 return $this->relationExists( $sequence, 'S', $schema );
1075         }
1076
1077         public function triggerExists( $table, $trigger ) {
1078                 $q = <<<SQL
1079         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1080                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1081                           AND tgrelid=pg_class.oid
1082                           AND nspname=%s AND relname=%s AND tgname=%s
1083 SQL;
1084                 $res = $this->query(
1085                         sprintf(
1086                                 $q,
1087                                 $this->addQuotes( $this->getCoreSchema() ),
1088                                 $this->addQuotes( $table ),
1089                                 $this->addQuotes( $trigger )
1090                         )
1091                 );
1092                 if ( !$res ) {
1093                         return null;
1094                 }
1095                 $rows = $res->numRows();
1096
1097                 return $rows;
1098         }
1099
1100         public function ruleExists( $table, $rule ) {
1101                 $exists = $this->selectField( 'pg_rules', 'rulename',
1102                         [
1103                                 'rulename' => $rule,
1104                                 'tablename' => $table,
1105                                 'schemaname' => $this->getCoreSchema()
1106                         ]
1107                 );
1108
1109                 return $exists === $rule;
1110         }
1111
1112         public function constraintExists( $table, $constraint ) {
1113                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1114                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1115                         $this->addQuotes( $this->getCoreSchema() ),
1116                         $this->addQuotes( $table ),
1117                         $this->addQuotes( $constraint )
1118                 );
1119                 $res = $this->query( $sql );
1120                 if ( !$res ) {
1121                         return null;
1122                 }
1123                 $rows = $res->numRows();
1124
1125                 return $rows;
1126         }
1127
1128         /**
1129          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1130          * @param string $schema
1131          * @return bool
1132          */
1133         public function schemaExists( $schema ) {
1134                 if ( !strlen( $schema ) ) {
1135                         return false; // short-circuit
1136                 }
1137
1138                 $exists = $this->selectField(
1139                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1140
1141                 return (bool)$exists;
1142         }
1143
1144         /**
1145          * Returns true if a given role (i.e. user) exists, false otherwise.
1146          * @param string $roleName
1147          * @return bool
1148          */
1149         public function roleExists( $roleName ) {
1150                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1151                         [ 'rolname' => $roleName ], __METHOD__ );
1152
1153                 return (bool)$exists;
1154         }
1155
1156         /**
1157          * @var string $table
1158          * @var string $field
1159          * @return PostgresField|null
1160          */
1161         public function fieldInfo( $table, $field ) {
1162                 return PostgresField::fromText( $this, $table, $field );
1163         }
1164
1165         /**
1166          * pg_field_type() wrapper
1167          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1168          * @param int $index Field number, starting from 0
1169          * @return string
1170          */
1171         public function fieldType( $res, $index ) {
1172                 if ( $res instanceof ResultWrapper ) {
1173                         $res = $res->result;
1174                 }
1175
1176                 return pg_field_type( $res, $index );
1177         }
1178
1179         public function encodeBlob( $b ) {
1180                 return new PostgresBlob( pg_escape_bytea( $b ) );
1181         }
1182
1183         public function decodeBlob( $b ) {
1184                 if ( $b instanceof PostgresBlob ) {
1185                         $b = $b->fetch();
1186                 } elseif ( $b instanceof Blob ) {
1187                         return $b->fetch();
1188                 }
1189
1190                 return pg_unescape_bytea( $b );
1191         }
1192
1193         public function strencode( $s ) {
1194                 // Should not be called by us
1195                 return pg_escape_string( $this->getBindingHandle(), $s );
1196         }
1197
1198         public function addQuotes( $s ) {
1199                 $conn = $this->getBindingHandle();
1200
1201                 if ( is_null( $s ) ) {
1202                         return 'NULL';
1203                 } elseif ( is_bool( $s ) ) {
1204                         return intval( $s );
1205                 } elseif ( $s instanceof Blob ) {
1206                         if ( $s instanceof PostgresBlob ) {
1207                                 $s = $s->fetch();
1208                         } else {
1209                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1210                         }
1211                         return "'$s'";
1212                 }
1213
1214                 return "'" . pg_escape_string( $conn, $s ) . "'";
1215         }
1216
1217         /**
1218          * Postgres specific version of replaceVars.
1219          * Calls the parent version in Database.php
1220          *
1221          * @param string $ins SQL string, read from a stream (usually tables.sql)
1222          * @return string SQL string
1223          */
1224         protected function replaceVars( $ins ) {
1225                 $ins = parent::replaceVars( $ins );
1226
1227                 if ( $this->numericVersion >= 8.3 ) {
1228                         // Thanks for not providing backwards-compatibility, 8.3
1229                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1230                 }
1231
1232                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1233                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1234                 }
1235
1236                 return $ins;
1237         }
1238
1239         public function makeSelectOptions( $options ) {
1240                 $preLimitTail = $postLimitTail = '';
1241                 $startOpts = $useIndex = $ignoreIndex = '';
1242
1243                 $noKeyOptions = [];
1244                 foreach ( $options as $key => $option ) {
1245                         if ( is_numeric( $key ) ) {
1246                                 $noKeyOptions[$option] = true;
1247                         }
1248                 }
1249
1250                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1251
1252                 $preLimitTail .= $this->makeOrderBy( $options );
1253
1254                 // if ( isset( $options['LIMIT'] ) ) {
1255                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1256                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1257                 //              : false );
1258                 // }
1259
1260                 if ( isset( $options['FOR UPDATE'] ) ) {
1261                         $postLimitTail .= ' FOR UPDATE OF ' .
1262                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1263                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1264                         $postLimitTail .= ' FOR UPDATE';
1265                 }
1266
1267                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1268                         $startOpts .= 'DISTINCT';
1269                 }
1270
1271                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1272         }
1273
1274         public function getDBname() {
1275                 return $this->mDBname;
1276         }
1277
1278         public function getServer() {
1279                 return $this->mServer;
1280         }
1281
1282         public function buildConcat( $stringList ) {
1283                 return implode( ' || ', $stringList );
1284         }
1285
1286         public function buildGroupConcatField(
1287                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1288         ) {
1289                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1290
1291                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1292         }
1293
1294         public function buildStringCast( $field ) {
1295                 return $field . '::text';
1296         }
1297
1298         public function streamStatementEnd( &$sql, &$newLine ) {
1299                 # Allow dollar quoting for function declarations
1300                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1301                         if ( $this->delimiter ) {
1302                                 $this->delimiter = false;
1303                         } else {
1304                                 $this->delimiter = ';';
1305                         }
1306                 }
1307
1308                 return parent::streamStatementEnd( $sql, $newLine );
1309         }
1310
1311         public function lockIsFree( $lockName, $method ) {
1312                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1313                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1314                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1315                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1316                 $row = $this->fetchObject( $result );
1317
1318                 return ( $row->lockstatus === 't' );
1319         }
1320
1321         public function lock( $lockName, $method, $timeout = 5 ) {
1322                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1323                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1324                 $loop = new WaitConditionLoop(
1325                         function () use ( $lockName, $key, $timeout, $method ) {
1326                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1327                                 $row = $this->fetchObject( $res );
1328                                 if ( $row->lockstatus === 't' ) {
1329                                         parent::lock( $lockName, $method, $timeout ); // record
1330                                         return true;
1331                                 }
1332
1333                                 return WaitConditionLoop::CONDITION_CONTINUE;
1334                         },
1335                         $timeout
1336                 );
1337
1338                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1339         }
1340
1341         public function unlock( $lockName, $method ) {
1342                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1343                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1344                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1345                 $row = $this->fetchObject( $result );
1346
1347                 if ( $row->lockstatus === 't' ) {
1348                         parent::unlock( $lockName, $method ); // record
1349                         return true;
1350                 }
1351
1352                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1353
1354                 return false;
1355         }
1356
1357         /**
1358          * @param string $lockName
1359          * @return string Integer
1360          */
1361         private function bigintFromLockName( $lockName ) {
1362                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1363         }
1364 }