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