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 use Wikimedia\Rdbms\Blob;
  25 use Wikimedia\Rdbms\PostgresBlob;
  26 use Wikimedia\Rdbms\PostgresField;
  27
  28 /**
  29  * @ingroup Database
  30  */
  31 class DatabasePostgres extends Database {
  32         /** @var int|bool */
  33         protected $port;
  34
  35         /** @var resource */
  36         protected $mLastResult = null;
  37         /** @var int The number of rows affected as an integer */
  38         protected $mAffectedRows = null;
  39
  40         /** @var int */
  41         private $mInsertId = null;
  42         /** @var float|string */
  43         private $numericVersion = null;
  44         /** @var string Connect string to open a PostgreSQL connection */
  45         private $connectString;
  46         /** @var string */
  47         private $mCoreSchema;
  48         /** @var string[] Map of (reserved table name => alternate table name) */
  49         private $keywordTableMap = [];
  50
  51         /**
  52          * @see Database::__construct()
  53          * @param array $params Additional parameters include:
  54          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  55          */
  56         public function __construct( array $params ) {
  57                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  58                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  59                         ? $params['keywordTableMap']
  60                         : [];
  61
  62                 parent::__construct( $params );
  63         }
  64
  65         public function getType() {
  66                 return 'postgres';
  67         }
  68
  69         public function implicitGroupby() {
  70                 return false;
  71         }
  72
  73         public function implicitOrderby() {
  74                 return false;
  75         }
  76
  77         public function hasConstraint( $name ) {
  78                 $conn = $this->getBindingHandle();
  79
  80                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  81                         "WHERE c.connamespace = n.oid AND conname = '" .
  82                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  83                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  84                 $res = $this->doQuery( $sql );
  85
  86                 return $this->numRows( $res );
  87         }
  88
  89         public function open( $server, $user, $password, $dbName ) {
  90                 # Test for Postgres support, to avoid suppressed fatal error
  91                 if ( !function_exists( 'pg_connect' ) ) {
  92                         throw new DBConnectionError(
  93                                 $this,
  94                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  95                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  96                                 "webserver and database)\n"
  97                         );
  98                 }
  99
 100                 $this->mServer = $server;
 101                 $this->mUser = $user;
 102                 $this->mPassword = $password;
 103                 $this->mDBname = $dbName;
 104
 105                 $connectVars = [
 106                         'dbname' => $dbName,
 107                         'user' => $user,
 108                         'password' => $password
 109                 ];
 110                 if ( $server != false && $server != '' ) {
 111                         $connectVars['host'] = $server;
 112                 }
 113                 if ( (int)$this->port > 0 ) {
 114                         $connectVars['port'] = (int)$this->port;
 115                 }
 116                 if ( $this->mFlags & self::DBO_SSL ) {
 117                         $connectVars['sslmode'] = 1;
 118                 }
 119
 120                 $this->connectString = $this->makeConnectionString( $connectVars );
 121                 $this->close();
 122                 $this->installErrorHandler();
 123
 124                 try {
 125                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 126                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 127                 } catch ( Exception $ex ) {
 128                         $this->restoreErrorHandler();
 129                         throw $ex;
 130                 }
 131
 132                 $phpError = $this->restoreErrorHandler();
 133
 134                 if ( !$this->mConn ) {
 135                         $this->queryLogger->debug(
 136                                 "DB connection error\n" .
 137                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 138                                 substr( $password, 0, 3 ) . "...\n"
 139                         );
 140                         $this->queryLogger->debug( $this->lastError() . "\n" );
 141                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 142                 }
 143
 144                 $this->mOpened = true;
 145
 146                 # If called from the command-line (e.g. importDump), only show errors
 147                 if ( $this->cliMode ) {
 148                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 149                 }
 150
 151                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 152                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 153                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 154                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 155                 if ( $this->getServerVersion() >= 9.0 ) {
 156                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 157                 }
 158
 159                 $this->determineCoreSchema( $this->mSchema );
 160                 // The schema to be used is now in the search path; no need for explicit qualification
 161                 $this->mSchema = '';
 162
 163                 return $this->mConn;
 164         }
 165
 166         /**
 167          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 168          * DB name doesn't match the open connection, open a new one
 169          * @param string $db
 170          * @return bool
 171          */
 172         public function selectDB( $db ) {
 173                 if ( $this->mDBname !== $db ) {
 174                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 175                 } else {
 176                         return true;
 177                 }
 178         }
 179
 180         /**
 181          * @param string[] $vars
 182          * @return string
 183          */
 184         private function makeConnectionString( $vars ) {
 185                 $s = '';
 186                 foreach ( $vars as $name => $value ) {
 187                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 188                 }
 189
 190                 return $s;
 191         }
 192
 193         protected function closeConnection() {
 194                 return $this->mConn ? pg_close( $this->mConn ) : true;
 195         }
 196
 197         public function doQuery( $sql ) {
 198                 $conn = $this->getBindingHandle();
 199
 200                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 201                 // Clear previously left over PQresult
 202                 while ( $res = pg_get_result( $conn ) ) {
 203                         pg_free_result( $res );
 204                 }
 205                 if ( pg_send_query( $conn, $sql ) === false ) {
 206                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 207                 }
 208                 $this->mLastResult = pg_get_result( $conn );
 209                 $this->mAffectedRows = null;
 210                 if ( pg_result_error( $this->mLastResult ) ) {
 211                         return false;
 212                 }
 213
 214                 return $this->mLastResult;
 215         }
 216
 217         protected function dumpError() {
 218                 $diags = [
 219                         PGSQL_DIAG_SEVERITY,
 220                         PGSQL_DIAG_SQLSTATE,
 221                         PGSQL_DIAG_MESSAGE_PRIMARY,
 222                         PGSQL_DIAG_MESSAGE_DETAIL,
 223                         PGSQL_DIAG_MESSAGE_HINT,
 224                         PGSQL_DIAG_STATEMENT_POSITION,
 225                         PGSQL_DIAG_INTERNAL_POSITION,
 226                         PGSQL_DIAG_INTERNAL_QUERY,
 227                         PGSQL_DIAG_CONTEXT,
 228                         PGSQL_DIAG_SOURCE_FILE,
 229                         PGSQL_DIAG_SOURCE_LINE,
 230                         PGSQL_DIAG_SOURCE_FUNCTION
 231                 ];
 232                 foreach ( $diags as $d ) {
 233                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 234                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 235                 }
 236         }
 237
 238         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 239                 if ( $tempIgnore ) {
 240                         /* Check for constraint violation */
 241                         if ( $errno === '23505' ) {
 242                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 243
 244                                 return;
 245                         }
 246                 }
 247                 /* Transaction stays in the ERROR state until rolled back */
 248                 if ( $this->mTrxLevel ) {
 249                         $this->rollback( __METHOD__ );
 250                 }
 251                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 252         }
 253
 254         public function freeResult( $res ) {
 255                 if ( $res instanceof ResultWrapper ) {
 256                         $res = $res->result;
 257                 }
 258                 MediaWiki\suppressWarnings();
 259                 $ok = pg_free_result( $res );
 260                 MediaWiki\restoreWarnings();
 261                 if ( !$ok ) {
 262                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 263                 }
 264         }
 265
 266         public function fetchObject( $res ) {
 267                 if ( $res instanceof ResultWrapper ) {
 268                         $res = $res->result;
 269                 }
 270                 MediaWiki\suppressWarnings();
 271                 $row = pg_fetch_object( $res );
 272                 MediaWiki\restoreWarnings();
 273                 # @todo FIXME: HACK HACK HACK HACK debug
 274
 275                 # @todo hashar: not sure if the following test really trigger if the object
 276                 #          fetching failed.
 277                 $conn = $this->getBindingHandle();
 278                 if ( pg_last_error( $conn ) ) {
 279                         throw new DBUnexpectedError(
 280                                 $this,
 281                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 282                         );
 283                 }
 284
 285                 return $row;
 286         }
 287
 288         public function fetchRow( $res ) {
 289                 if ( $res instanceof ResultWrapper ) {
 290                         $res = $res->result;
 291                 }
 292                 MediaWiki\suppressWarnings();
 293                 $row = pg_fetch_array( $res );
 294                 MediaWiki\restoreWarnings();
 295
 296                 $conn = $this->getBindingHandle();
 297                 if ( pg_last_error( $conn ) ) {
 298                         throw new DBUnexpectedError(
 299                                 $this,
 300                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 301                         );
 302                 }
 303
 304                 return $row;
 305         }
 306
 307         public function numRows( $res ) {
 308                 if ( $res instanceof ResultWrapper ) {
 309                         $res = $res->result;
 310                 }
 311                 MediaWiki\suppressWarnings();
 312                 $n = pg_num_rows( $res );
 313                 MediaWiki\restoreWarnings();
 314
 315                 $conn = $this->getBindingHandle();
 316                 if ( pg_last_error( $conn ) ) {
 317                         throw new DBUnexpectedError(
 318                                 $this,
 319                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 320                         );
 321                 }
 322
 323                 return $n;
 324         }
 325
 326         public function numFields( $res ) {
 327                 if ( $res instanceof ResultWrapper ) {
 328                         $res = $res->result;
 329                 }
 330
 331                 return pg_num_fields( $res );
 332         }
 333
 334         public function fieldName( $res, $n ) {
 335                 if ( $res instanceof ResultWrapper ) {
 336                         $res = $res->result;
 337                 }
 338
 339                 return pg_field_name( $res, $n );
 340         }
 341
 342         /**
 343          * Return the result of the last call to nextSequenceValue();
 344          * This must be called after nextSequenceValue().
 345          *
 346          * @return int|null
 347          */
 348         public function insertId() {
 349                 return $this->mInsertId;
 350         }
 351
 352         public function dataSeek( $res, $row ) {
 353                 if ( $res instanceof ResultWrapper ) {
 354                         $res = $res->result;
 355                 }
 356
 357                 return pg_result_seek( $res, $row );
 358         }
 359
 360         public function lastError() {
 361                 if ( $this->mConn ) {
 362                         if ( $this->mLastResult ) {
 363                                 return pg_result_error( $this->mLastResult );
 364                         } else {
 365                                 return pg_last_error();
 366                         }
 367                 }
 368
 369                 return $this->getLastPHPError() ?: 'No database connection';
 370         }
 371
 372         public function lastErrno() {
 373                 if ( $this->mLastResult ) {
 374                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 375                 } else {
 376                         return false;
 377                 }
 378         }
 379
 380         public function affectedRows() {
 381                 if ( !is_null( $this->mAffectedRows ) ) {
 382                         // Forced result for simulated queries
 383                         return $this->mAffectedRows;
 384                 }
 385                 if ( empty( $this->mLastResult ) ) {
 386                         return 0;
 387                 }
 388
 389                 return pg_affected_rows( $this->mLastResult );
 390         }
 391
 392         /**
 393          * Estimate rows in dataset
 394          * Returns estimated count, based on EXPLAIN output
 395          * This is not necessarily an accurate estimate, so use sparingly
 396          * Returns -1 if count cannot be found
 397          * Takes same arguments as Database::select()
 398          *
 399          * @param string $table
 400          * @param string $vars
 401          * @param string $conds
 402          * @param string $fname
 403          * @param array $options
 404          * @return int
 405          */
 406         public function estimateRowCount( $table, $vars = '*', $conds = '',
 407                 $fname = __METHOD__, $options = []
 408         ) {
 409                 $options['EXPLAIN'] = true;
 410                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 411                 $rows = -1;
 412                 if ( $res ) {
 413                         $row = $this->fetchRow( $res );
 414                         $count = [];
 415                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 416                                 $rows = (int)$count[1];
 417                         }
 418                 }
 419
 420                 return $rows;
 421         }
 422
 423         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 424                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 425                 $res = $this->query( $sql, $fname );
 426                 if ( !$res ) {
 427                         return null;
 428                 }
 429                 foreach ( $res as $row ) {
 430                         if ( $row->indexname == $this->indexName( $index ) ) {
 431                                 return $row;
 432                         }
 433                 }
 434
 435                 return false;
 436         }
 437
 438         public function indexAttributes( $index, $schema = false ) {
 439                 if ( $schema === false ) {
 440                         $schema = $this->getCoreSchema();
 441                 }
 442                 /*
 443                  * A subquery would be not needed if we didn't care about the order
 444                  * of attributes, but we do
 445                  */
 446                 $sql = <<<__INDEXATTR__
 447
 448                         SELECT opcname,
 449                                 attname,
 450                                 i.indoption[s.g] as option,
 451                                 pg_am.amname
 452                         FROM
 453                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 454                                         FROM
 455                                                 pg_index isub
 456                                         JOIN pg_class cis
 457                                                 ON cis.oid=isub.indexrelid
 458                                         JOIN pg_namespace ns
 459                                                 ON cis.relnamespace = ns.oid
 460                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 461                                 pg_attribute,
 462                                 pg_opclass opcls,
 463                                 pg_am,
 464                                 pg_class ci
 465                                 JOIN pg_index i
 466                                         ON ci.oid=i.indexrelid
 467                                 JOIN pg_class ct
 468                                         ON ct.oid = i.indrelid
 469                                 JOIN pg_namespace n
 470                                         ON ci.relnamespace = n.oid
 471                                 WHERE
 472                                         ci.relname='$index' AND n.nspname='$schema'
 473                                         AND     attrelid = ct.oid
 474                                         AND     i.indkey[s.g] = attnum
 475                                         AND     i.indclass[s.g] = opcls.oid
 476                                         AND     pg_am.oid = opcls.opcmethod
 477 __INDEXATTR__;
 478                 $res = $this->query( $sql, __METHOD__ );
 479                 $a = [];
 480                 if ( $res ) {
 481                         foreach ( $res as $row ) {
 482                                 $a[] = [
 483                                         $row->attname,
 484                                         $row->opcname,
 485                                         $row->amname,
 486                                         $row->option ];
 487                         }
 488                 } else {
 489                         return null;
 490                 }
 491
 492                 return $a;
 493         }
 494
 495         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 496                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 497                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 498                         $this->strencode( $this->indexName( $index ) ) .
 499                         ")'";
 500                 $res = $this->query( $sql, $fname );
 501                 if ( !$res ) {
 502                         return null;
 503                 }
 504
 505                 return $res->numRows() > 0;
 506         }
 507
 508         public function selectSQLText(
 509                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 510         ) {
 511                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 512                 // to the parent function to get the actual SQL text.
 513                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 514                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 515                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 516                 // accordingly.
 517                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 518                 if ( is_array( $options ) ) {
 519                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 520                         if ( $forUpdateKey !== false && $join_conds ) {
 521                                 unset( $options[$forUpdateKey] );
 522
 523                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 524                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 525                                                 $options['FOR UPDATE'][] = $table_cond;
 526                                         }
 527                                 }
 528                         }
 529
 530                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 531                                 unset( $options['ORDER BY'] );
 532                         }
 533                 }
 534
 535                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 536         }
 537
 538         /**
 539          * INSERT wrapper, inserts an array into a table
 540          *
 541          * $args may be a single associative array, or an array of these with numeric keys,
 542          * for multi-row insert (Postgres version 8.2 and above only).
 543          *
 544          * @param string $table Name of the table to insert to.
 545          * @param array $args Items to insert into the table.
 546          * @param string $fname Name of the function, for profiling
 547          * @param array|string $options String or array. Valid options: IGNORE
 548          * @return bool Success of insert operation. IGNORE always returns true.
 549          */
 550         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 551                 if ( !count( $args ) ) {
 552                         return true;
 553                 }
 554
 555                 $table = $this->tableName( $table );
 556                 if ( !isset( $this->numericVersion ) ) {
 557                         $this->getServerVersion();
 558                 }
 559
 560                 if ( !is_array( $options ) ) {
 561                         $options = [ $options ];
 562                 }
 563
 564                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 565                         $multi = true;
 566                         $keys = array_keys( $args[0] );
 567                 } else {
 568                         $multi = false;
 569                         $keys = array_keys( $args );
 570                 }
 571
 572                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 573                 $savepoint = $olde = null;
 574                 $numrowsinserted = 0;
 575                 if ( in_array( 'IGNORE', $options ) ) {
 576                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 577                         $olde = error_reporting( 0 );
 578                         // For future use, we may want to track the number of actual inserts
 579                         // Right now, insert (all writes) simply return true/false
 580                 }
 581
 582                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 583
 584                 if ( $multi ) {
 585                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 586                                 $first = true;
 587                                 foreach ( $args as $row ) {
 588                                         if ( $first ) {
 589                                                 $first = false;
 590                                         } else {
 591                                                 $sql .= ',';
 592                                         }
 593                                         $sql .= '(' . $this->makeList( $row ) . ')';
 594                                 }
 595                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 596                         } else {
 597                                 $res = true;
 598                                 $origsql = $sql;
 599                                 foreach ( $args as $row ) {
 600                                         $tempsql = $origsql;
 601                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 602
 603                                         if ( $savepoint ) {
 604                                                 $savepoint->savepoint();
 605                                         }
 606
 607                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 608
 609                                         if ( $savepoint ) {
 610                                                 $bar = pg_result_error( $this->mLastResult );
 611                                                 if ( $bar != false ) {
 612                                                         $savepoint->rollback();
 613                                                 } else {
 614                                                         $savepoint->release();
 615                                                         $numrowsinserted++;
 616                                                 }
 617                                         }
 618
 619                                         // If any of them fail, we fail overall for this function call
 620                                         // Note that this will be ignored if IGNORE is set
 621                                         if ( !$tempres ) {
 622                                                 $res = false;
 623                                         }
 624                                 }
 625                         }
 626                 } else {
 627                         // Not multi, just a lone insert
 628                         if ( $savepoint ) {
 629                                 $savepoint->savepoint();
 630                         }
 631
 632                         $sql .= '(' . $this->makeList( $args ) . ')';
 633                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 634                         if ( $savepoint ) {
 635                                 $bar = pg_result_error( $this->mLastResult );
 636                                 if ( $bar != false ) {
 637                                         $savepoint->rollback();
 638                                 } else {
 639                                         $savepoint->release();
 640                                         $numrowsinserted++;
 641                                 }
 642                         }
 643                 }
 644                 if ( $savepoint ) {
 645                         error_reporting( $olde );
 646                         $savepoint->commit();
 647
 648                         // Set the affected row count for the whole operation
 649                         $this->mAffectedRows = $numrowsinserted;
 650
 651                         // IGNORE always returns true
 652                         return true;
 653                 }
 654
 655                 return $res;
 656         }
 657
 658         /**
 659          * INSERT SELECT wrapper
 660          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 661          * Source items may be literals rather then field names, but strings should
 662          * be quoted with Database::addQuotes()
 663          * $conds may be "*" to copy the whole table
 664          * srcTable may be an array of tables.
 665          * @todo FIXME: Implement this a little better (seperate select/insert)?
 666          *
 667          * @param string $destTable
 668          * @param array|string $srcTable
 669          * @param array $varMap
 670          * @param array $conds
 671          * @param string $fname
 672          * @param array $insertOptions
 673          * @param array $selectOptions
 674          * @return bool
 675          */
 676         public function nativeInsertSelect(
 677                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 678                 $insertOptions = [], $selectOptions = []
 679         ) {
 680                 $destTable = $this->tableName( $destTable );
 681
 682                 if ( !is_array( $insertOptions ) ) {
 683                         $insertOptions = [ $insertOptions ];
 684                 }
 685
 686                 /*
 687                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 688                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 689                  */
 690                 $savepoint = $olde = null;
 691                 $numrowsinserted = 0;
 692                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 693                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 694                         $olde = error_reporting( 0 );
 695                         $savepoint->savepoint();
 696                 }
 697
 698                 if ( !is_array( $selectOptions ) ) {
 699                         $selectOptions = [ $selectOptions ];
 700                 }
 701                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 702                         $this->makeSelectOptions( $selectOptions );
 703                 if ( is_array( $srcTable ) ) {
 704                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
 705                 } else {
 706                         $srcTable = $this->tableName( $srcTable );
 707                 }
 708
 709                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 710                         " SELECT $startOpts " . implode( ',', $varMap ) .
 711                         " FROM $srcTable $useIndex $ignoreIndex ";
 712
 713                 if ( $conds != '*' ) {
 714                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 715                 }
 716
 717                 $sql .= " $tailOpts";
 718
 719                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 720                 if ( $savepoint ) {
 721                         $bar = pg_result_error( $this->mLastResult );
 722                         if ( $bar != false ) {
 723                                 $savepoint->rollback();
 724                         } else {
 725                                 $savepoint->release();
 726                                 $numrowsinserted++;
 727                         }
 728                         error_reporting( $olde );
 729                         $savepoint->commit();
 730
 731                         // Set the affected row count for the whole operation
 732                         $this->mAffectedRows = $numrowsinserted;
 733
 734                         // IGNORE always returns true
 735                         return true;
 736                 }
 737
 738                 return $res;
 739         }
 740
 741         public function tableName( $name, $format = 'quoted' ) {
 742                 // Replace reserved words with better ones
 743                 $name = $this->remappedTableName( $name );
 744
 745                 return parent::tableName( $name, $format );
 746         }
 747
 748         /**
 749          * @param string $name
 750          * @return string Value of $name or remapped name if $name is a reserved keyword
 751          */
 752         public function remappedTableName( $name ) {
 753                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 754         }
 755
 756         /**
 757          * @param string $name
 758          * @param string $format
 759          * @return string Qualified and encoded (if requested) table name
 760          */
 761         public function realTableName( $name, $format = 'quoted' ) {
 762                 return parent::tableName( $name, $format );
 763         }
 764
 765         public function nextSequenceValue( $seqName ) {
 766                 $safeseq = str_replace( "'", "''", $seqName );
 767                 $res = $this->query( "SELECT nextval('$safeseq')" );
 768                 $row = $this->fetchRow( $res );
 769                 $this->mInsertId = $row[0];
 770
 771                 return $this->mInsertId;
 772         }
 773
 774         /**
 775          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 776          *
 777          * @param string $seqName
 778          * @return int
 779          */
 780         public function currentSequenceValue( $seqName ) {
 781                 $safeseq = str_replace( "'", "''", $seqName );
 782                 $res = $this->query( "SELECT currval('$safeseq')" );
 783                 $row = $this->fetchRow( $res );
 784                 $currval = $row[0];
 785
 786                 return $currval;
 787         }
 788
 789         public function textFieldSize( $table, $field ) {
 790                 $table = $this->tableName( $table );
 791                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 792                         FROM pg_class c, pg_attribute a, pg_type t
 793                         WHERE relname='$table' AND a.attrelid=c.oid AND
 794                                 a.atttypid=t.oid and a.attname='$field'";
 795                 $res = $this->query( $sql );
 796                 $row = $this->fetchObject( $res );
 797                 if ( $row->ftype == 'varchar' ) {
 798                         $size = $row->size - 4;
 799                 } else {
 800                         $size = $row->size;
 801                 }
 802
 803                 return $size;
 804         }
 805
 806         public function limitResult( $sql, $limit, $offset = false ) {
 807                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 808         }
 809
 810         public function wasDeadlock() {
 811                 return $this->lastErrno() == '40P01';
 812         }
 813
 814         public function duplicateTableStructure(
 815                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 816         ) {
 817                 $newName = $this->addIdentifierQuotes( $newName );
 818                 $oldName = $this->addIdentifierQuotes( $oldName );
 819
 820                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 821                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 822         }
 823
 824         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 825                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 826                 $result = $this->query(
 827                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 828                 $endArray = [];
 829
 830                 foreach ( $result as $table ) {
 831                         $vars = get_object_vars( $table );
 832                         $table = array_pop( $vars );
 833                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 834                                 $endArray[] = $table;
 835                         }
 836                 }
 837
 838                 return $endArray;
 839         }
 840
 841         public function timestamp( $ts = 0 ) {
 842                 $ct = new ConvertibleTimestamp( $ts );
 843
 844                 return $ct->getTimestamp( TS_POSTGRES );
 845         }
 846
 847         /**
 848          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 849          * to https://secure.php.net/manual/en/ref.pgsql.php
 850          *
 851          * Parsing a postgres array can be a tricky problem, he's my
 852          * take on this, it handles multi-dimensional arrays plus
 853          * escaping using a nasty regexp to determine the limits of each
 854          * data-item.
 855          *
 856          * This should really be handled by PHP PostgreSQL module
 857          *
 858          * @since 1.19
 859          * @param string $text Postgreql array returned in a text form like {a,b}
 860          * @param string $output
 861          * @param int|bool $limit
 862          * @param int $offset
 863          * @return string
 864          */
 865         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 866                 if ( false === $limit ) {
 867                         $limit = strlen( $text ) - 1;
 868                         $output = [];
 869                 }
 870                 if ( '{}' == $text ) {
 871                         return $output;
 872                 }
 873                 do {
 874                         if ( '{' != $text[$offset] ) {
 875                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 876                                         $text, $match, 0, $offset );
 877                                 $offset += strlen( $match[0] );
 878                                 $output[] = ( '"' != $match[1][0]
 879                                         ? $match[1]
 880                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 881                                 if ( '},' == $match[3] ) {
 882                                         return $output;
 883                                 }
 884                         } else {
 885                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 886                         }
 887                 } while ( $limit > $offset );
 888
 889                 return $output;
 890         }
 891
 892         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 893                 return $valuedata;
 894         }
 895
 896         public function getSoftwareLink() {
 897                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 898         }
 899
 900         /**
 901          * Return current schema (executes SELECT current_schema())
 902          * Needs transaction
 903          *
 904          * @since 1.19
 905          * @return string Default schema for the current session
 906          */
 907         public function getCurrentSchema() {
 908                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 909                 $row = $this->fetchRow( $res );
 910
 911                 return $row[0];
 912         }
 913
 914         /**
 915          * Return list of schemas which are accessible without schema name
 916          * This is list does not contain magic keywords like "$user"
 917          * Needs transaction
 918          *
 919          * @see getSearchPath()
 920          * @see setSearchPath()
 921          * @since 1.19
 922          * @return array List of actual schemas for the current sesson
 923          */
 924         public function getSchemas() {
 925                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 926                 $row = $this->fetchRow( $res );
 927                 $schemas = [];
 928
 929                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 930
 931                 return $this->pg_array_parse( $row[0], $schemas );
 932         }
 933
 934         /**
 935          * Return search patch for schemas
 936          * This is different from getSchemas() since it contain magic keywords
 937          * (like "$user").
 938          * Needs transaction
 939          *
 940          * @since 1.19
 941          * @return array How to search for table names schemas for the current user
 942          */
 943         public function getSearchPath() {
 944                 $res = $this->query( "SHOW search_path", __METHOD__ );
 945                 $row = $this->fetchRow( $res );
 946
 947                 /* PostgreSQL returns SHOW values as strings */
 948
 949                 return explode( ",", $row[0] );
 950         }
 951
 952         /**
 953          * Update search_path, values should already be sanitized
 954          * Values may contain magic keywords like "$user"
 955          * @since 1.19
 956          *
 957          * @param array $search_path List of schemas to be searched by default
 958          */
 959         private function setSearchPath( $search_path ) {
 960                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 961         }
 962
 963         /**
 964          * Determine default schema for the current application
 965          * Adjust this session schema search path if desired schema exists
 966          * and is not alread there.
 967          *
 968          * We need to have name of the core schema stored to be able
 969          * to query database metadata.
 970          *
 971          * This will be also called by the installer after the schema is created
 972          *
 973          * @since 1.19
 974          *
 975          * @param string $desiredSchema
 976          */
 977         public function determineCoreSchema( $desiredSchema ) {
 978                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 979                 if ( $this->schemaExists( $desiredSchema ) ) {
 980                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 981                                 $this->mCoreSchema = $desiredSchema;
 982                                 $this->queryLogger->debug(
 983                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 984                         } else {
 985                                 /**
 986                                  * Prepend our schema (e.g. 'mediawiki') in front
 987                                  * of the search path
 988                                  * Fixes T17816
 989                                  */
 990                                 $search_path = $this->getSearchPath();
 991                                 array_unshift( $search_path,
 992                                         $this->addIdentifierQuotes( $desiredSchema ) );
 993                                 $this->setSearchPath( $search_path );
 994                                 $this->mCoreSchema = $desiredSchema;
 995                                 $this->queryLogger->debug(
 996                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 997                         }
 998                 } else {
 999                         $this->mCoreSchema = $this->getCurrentSchema();
1000                         $this->queryLogger->debug(
1001                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1002                                 $this->mCoreSchema . "\"\n" );
1003                 }
1004                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1005                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1006         }
1007
1008         /**
1009          * Return schema name for core application tables
1010          *
1011          * @since 1.19
1012          * @return string Core schema name
1013          */
1014         public function getCoreSchema() {
1015                 return $this->mCoreSchema;
1016         }
1017
1018         public function getServerVersion() {
1019                 if ( !isset( $this->numericVersion ) ) {
1020                         $conn = $this->getBindingHandle();
1021                         $versionInfo = pg_version( $conn );
1022                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1023                                 // Old client, abort install
1024                                 $this->numericVersion = '7.3 or earlier';
1025                         } elseif ( isset( $versionInfo['server'] ) ) {
1026                                 // Normal client
1027                                 $this->numericVersion = $versionInfo['server'];
1028                         } else {
1029                                 // T18937: broken pgsql extension from PHP<5.3
1030                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1031                         }
1032                 }
1033
1034                 return $this->numericVersion;
1035         }
1036
1037         /**
1038          * Query whether a given relation exists (in the given schema, or the
1039          * default mw one if not given)
1040          * @param string $table
1041          * @param array|string $types
1042          * @param bool|string $schema
1043          * @return bool
1044          */
1045         private function relationExists( $table, $types, $schema = false ) {
1046                 if ( !is_array( $types ) ) {
1047                         $types = [ $types ];
1048                 }
1049                 if ( $schema === false ) {
1050                         $schema = $this->getCoreSchema();
1051                 }
1052                 $etable = $this->addQuotes( $table );
1053                 $eschema = $this->addQuotes( $schema );
1054                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1055                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1056                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1057                 $res = $this->query( $sql );
1058                 $count = $res ? $res->numRows() : 0;
1059
1060                 return (bool)$count;
1061         }
1062
1063         /**
1064          * For backward compatibility, this function checks both tables and views.
1065          * @param string $table
1066          * @param string $fname
1067          * @param bool|string $schema
1068          * @return bool
1069          */
1070         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1071                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1072         }
1073
1074         public function sequenceExists( $sequence, $schema = false ) {
1075                 return $this->relationExists( $sequence, 'S', $schema );
1076         }
1077
1078         public function triggerExists( $table, $trigger ) {
1079                 $q = <<<SQL
1080         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1081                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1082                         AND tgrelid=pg_class.oid
1083                         AND nspname=%s AND relname=%s AND tgname=%s
1084 SQL;
1085                 $res = $this->query(
1086                         sprintf(
1087                                 $q,
1088                                 $this->addQuotes( $this->getCoreSchema() ),
1089                                 $this->addQuotes( $table ),
1090                                 $this->addQuotes( $trigger )
1091                         )
1092                 );
1093                 if ( !$res ) {
1094                         return null;
1095                 }
1096                 $rows = $res->numRows();
1097
1098                 return $rows;
1099         }
1100
1101         public function ruleExists( $table, $rule ) {
1102                 $exists = $this->selectField( 'pg_rules', 'rulename',
1103                         [
1104                                 'rulename' => $rule,
1105                                 'tablename' => $table,
1106                                 'schemaname' => $this->getCoreSchema()
1107                         ]
1108                 );
1109
1110                 return $exists === $rule;
1111         }
1112
1113         public function constraintExists( $table, $constraint ) {
1114                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1115                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1116                         $this->addQuotes( $this->getCoreSchema() ),
1117                         $this->addQuotes( $table ),
1118                         $this->addQuotes( $constraint )
1119                 );
1120                 $res = $this->query( $sql );
1121                 if ( !$res ) {
1122                         return null;
1123                 }
1124                 $rows = $res->numRows();
1125
1126                 return $rows;
1127         }
1128
1129         /**
1130          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1131          * @param string $schema
1132          * @return bool
1133          */
1134         public function schemaExists( $schema ) {
1135                 if ( !strlen( $schema ) ) {
1136                         return false; // short-circuit
1137                 }
1138
1139                 $exists = $this->selectField(
1140                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1141
1142                 return (bool)$exists;
1143         }
1144
1145         /**
1146          * Returns true if a given role (i.e. user) exists, false otherwise.
1147          * @param string $roleName
1148          * @return bool
1149          */
1150         public function roleExists( $roleName ) {
1151                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1152                         [ 'rolname' => $roleName ], __METHOD__ );
1153
1154                 return (bool)$exists;
1155         }
1156
1157         /**
1158          * @var string $table
1159          * @var string $field
1160          * @return PostgresField|null
1161          */
1162         public function fieldInfo( $table, $field ) {
1163                 return PostgresField::fromText( $this, $table, $field );
1164         }
1165
1166         /**
1167          * pg_field_type() wrapper
1168          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1169          * @param int $index Field number, starting from 0
1170          * @return string
1171          */
1172         public function fieldType( $res, $index ) {
1173                 if ( $res instanceof ResultWrapper ) {
1174                         $res = $res->result;
1175                 }
1176
1177                 return pg_field_type( $res, $index );
1178         }
1179
1180         public function encodeBlob( $b ) {
1181                 return new PostgresBlob( pg_escape_bytea( $b ) );
1182         }
1183
1184         public function decodeBlob( $b ) {
1185                 if ( $b instanceof PostgresBlob ) {
1186                         $b = $b->fetch();
1187                 } elseif ( $b instanceof Blob ) {
1188                         return $b->fetch();
1189                 }
1190
1191                 return pg_unescape_bytea( $b );
1192         }
1193
1194         public function strencode( $s ) {
1195                 // Should not be called by us
1196                 return pg_escape_string( $this->getBindingHandle(), $s );
1197         }
1198
1199         public function addQuotes( $s ) {
1200                 $conn = $this->getBindingHandle();
1201
1202                 if ( is_null( $s ) ) {
1203                         return 'NULL';
1204                 } elseif ( is_bool( $s ) ) {
1205                         return intval( $s );
1206                 } elseif ( $s instanceof Blob ) {
1207                         if ( $s instanceof PostgresBlob ) {
1208                                 $s = $s->fetch();
1209                         } else {
1210                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1211                         }
1212                         return "'$s'";
1213                 }
1214
1215                 return "'" . pg_escape_string( $conn, $s ) . "'";
1216         }
1217
1218         /**
1219          * Postgres specific version of replaceVars.
1220          * Calls the parent version in Database.php
1221          *
1222          * @param string $ins SQL string, read from a stream (usually tables.sql)
1223          * @return string SQL string
1224          */
1225         protected function replaceVars( $ins ) {
1226                 $ins = parent::replaceVars( $ins );
1227
1228                 if ( $this->numericVersion >= 8.3 ) {
1229                         // Thanks for not providing backwards-compatibility, 8.3
1230                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1231                 }
1232
1233                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1234                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1235                 }
1236
1237                 return $ins;
1238         }
1239
1240         public function makeSelectOptions( $options ) {
1241                 $preLimitTail = $postLimitTail = '';
1242                 $startOpts = $useIndex = $ignoreIndex = '';
1243
1244                 $noKeyOptions = [];
1245                 foreach ( $options as $key => $option ) {
1246                         if ( is_numeric( $key ) ) {
1247                                 $noKeyOptions[$option] = true;
1248                         }
1249                 }
1250
1251                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1252
1253                 $preLimitTail .= $this->makeOrderBy( $options );
1254
1255                 if ( isset( $options['FOR UPDATE'] ) ) {
1256                         $postLimitTail .= ' FOR UPDATE OF ' .
1257                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1258                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1259                         $postLimitTail .= ' FOR UPDATE';
1260                 }
1261
1262                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1263                         $startOpts .= 'DISTINCT';
1264                 }
1265
1266                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1267         }
1268
1269         public function getDBname() {
1270                 return $this->mDBname;
1271         }
1272
1273         public function getServer() {
1274                 return $this->mServer;
1275         }
1276
1277         public function buildConcat( $stringList ) {
1278                 return implode( ' || ', $stringList );
1279         }
1280
1281         public function buildGroupConcatField(
1282                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1283         ) {
1284                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1285
1286                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1287         }
1288
1289         public function buildStringCast( $field ) {
1290                 return $field . '::text';
1291         }
1292
1293         public function streamStatementEnd( &$sql, &$newLine ) {
1294                 # Allow dollar quoting for function declarations
1295                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1296                         if ( $this->delimiter ) {
1297                                 $this->delimiter = false;
1298                         } else {
1299                                 $this->delimiter = ';';
1300                         }
1301                 }
1302
1303                 return parent::streamStatementEnd( $sql, $newLine );
1304         }
1305
1306         public function lockIsFree( $lockName, $method ) {
1307                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1308                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1309                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1310                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1311                 $row = $this->fetchObject( $result );
1312
1313                 return ( $row->lockstatus === 't' );
1314         }
1315
1316         public function lock( $lockName, $method, $timeout = 5 ) {
1317                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1318                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1319                 $loop = new WaitConditionLoop(
1320                         function () use ( $lockName, $key, $timeout, $method ) {
1321                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1322                                 $row = $this->fetchObject( $res );
1323                                 if ( $row->lockstatus === 't' ) {
1324                                         parent::lock( $lockName, $method, $timeout ); // record
1325                                         return true;
1326                                 }
1327
1328                                 return WaitConditionLoop::CONDITION_CONTINUE;
1329                         },
1330                         $timeout
1331                 );
1332
1333                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1334         }
1335
1336         public function unlock( $lockName, $method ) {
1337                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1338                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1339                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1340                 $row = $this->fetchObject( $result );
1341
1342                 if ( $row->lockstatus === 't' ) {
1343                         parent::unlock( $lockName, $method ); // record
1344                         return true;
1345                 }
1346
1347                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1348
1349                 return false;
1350         }
1351
1352         /**
1353          * @param string $lockName
1354          * @return string Integer
1355          */
1356         private function bigintFromLockName( $lockName ) {
1357                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1358         }
1359 }