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 namespace Wikimedia\Rdbms;
  24
  25 use Wikimedia\Timestamp\ConvertibleTimestamp;
  26 use Wikimedia\WaitConditionLoop;
  27 use MediaWiki;
  28 use Exception;
  29
  30 /**
  31  * @ingroup Database
  32  */
  33 class DatabasePostgres extends Database {
  34         /** @var int|bool */
  35         protected $port;
  36
  37         /** @var resource */
  38         protected $mLastResult = null;
  39         /** @var int The number of rows affected as an integer */
  40         protected $mAffectedRows = null;
  41
  42         /** @var int */
  43         private $mInsertId = null;
  44         /** @var float|string */
  45         private $numericVersion = null;
  46         /** @var string Connect string to open a PostgreSQL connection */
  47         private $connectString;
  48         /** @var string */
  49         private $mCoreSchema;
  50         /** @var string[] Map of (reserved table name => alternate table name) */
  51         private $keywordTableMap = [];
  52
  53         /**
  54          * @see Database::__construct()
  55          * @param array $params Additional parameters include:
  56          *   - keywordTableMap : Map of reserved table names to alternative table names to use
  57          */
  58         public function __construct( array $params ) {
  59                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  60                 $this->keywordTableMap = isset( $params['keywordTableMap'] )
  61                         ? $params['keywordTableMap']
  62                         : [];
  63
  64                 parent::__construct( $params );
  65         }
  66
  67         public function getType() {
  68                 return 'postgres';
  69         }
  70
  71         public function implicitGroupby() {
  72                 return false;
  73         }
  74
  75         public function implicitOrderby() {
  76                 return false;
  77         }
  78
  79         public function hasConstraint( $name ) {
  80                 $conn = $this->getBindingHandle();
  81
  82                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  83                         "WHERE c.connamespace = n.oid AND conname = '" .
  84                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  85                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  86                 $res = $this->doQuery( $sql );
  87
  88                 return $this->numRows( $res );
  89         }
  90
  91         public function open( $server, $user, $password, $dbName ) {
  92                 # Test for Postgres support, to avoid suppressed fatal error
  93                 if ( !function_exists( 'pg_connect' ) ) {
  94                         throw new DBConnectionError(
  95                                 $this,
  96                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  97                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  98                                 "webserver and database)\n"
  99                         );
 100                 }
 101
 102                 $this->mServer = $server;
 103                 $this->mUser = $user;
 104                 $this->mPassword = $password;
 105                 $this->mDBname = $dbName;
 106
 107                 $connectVars = [
 108                         'dbname' => $dbName,
 109                         'user' => $user,
 110                         'password' => $password
 111                 ];
 112                 if ( $server != false && $server != '' ) {
 113                         $connectVars['host'] = $server;
 114                 }
 115                 if ( (int)$this->port > 0 ) {
 116                         $connectVars['port'] = (int)$this->port;
 117                 }
 118                 if ( $this->mFlags & self::DBO_SSL ) {
 119                         $connectVars['sslmode'] = 1;
 120                 }
 121
 122                 $this->connectString = $this->makeConnectionString( $connectVars );
 123                 $this->close();
 124                 $this->installErrorHandler();
 125
 126                 try {
 127                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 128                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 129                 } catch ( Exception $ex ) {
 130                         $this->restoreErrorHandler();
 131                         throw $ex;
 132                 }
 133
 134                 $phpError = $this->restoreErrorHandler();
 135
 136                 if ( !$this->mConn ) {
 137                         $this->queryLogger->debug(
 138                                 "DB connection error\n" .
 139                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 140                                 substr( $password, 0, 3 ) . "...\n"
 141                         );
 142                         $this->queryLogger->debug( $this->lastError() . "\n" );
 143                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 144                 }
 145
 146                 $this->mOpened = true;
 147
 148                 # If called from the command-line (e.g. importDump), only show errors
 149                 if ( $this->cliMode ) {
 150                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 151                 }
 152
 153                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 154                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 155                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 156                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 157                 if ( $this->getServerVersion() >= 9.0 ) {
 158                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 159                 }
 160
 161                 $this->determineCoreSchema( $this->mSchema );
 162                 // The schema to be used is now in the search path; no need for explicit qualification
 163                 $this->mSchema = '';
 164
 165                 return $this->mConn;
 166         }
 167
 168         /**
 169          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 170          * DB name doesn't match the open connection, open a new one
 171          * @param string $db
 172          * @return bool
 173          */
 174         public function selectDB( $db ) {
 175                 if ( $this->mDBname !== $db ) {
 176                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 177                 } else {
 178                         return true;
 179                 }
 180         }
 181
 182         /**
 183          * @param string[] $vars
 184          * @return string
 185          */
 186         private function makeConnectionString( $vars ) {
 187                 $s = '';
 188                 foreach ( $vars as $name => $value ) {
 189                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 190                 }
 191
 192                 return $s;
 193         }
 194
 195         protected function closeConnection() {
 196                 return $this->mConn ? pg_close( $this->mConn ) : true;
 197         }
 198
 199         public function doQuery( $sql ) {
 200                 $conn = $this->getBindingHandle();
 201
 202                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 203                 // Clear previously left over PQresult
 204                 while ( $res = pg_get_result( $conn ) ) {
 205                         pg_free_result( $res );
 206                 }
 207                 if ( pg_send_query( $conn, $sql ) === false ) {
 208                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 209                 }
 210                 $this->mLastResult = pg_get_result( $conn );
 211                 $this->mAffectedRows = null;
 212                 if ( pg_result_error( $this->mLastResult ) ) {
 213                         return false;
 214                 }
 215
 216                 return $this->mLastResult;
 217         }
 218
 219         protected function dumpError() {
 220                 $diags = [
 221                         PGSQL_DIAG_SEVERITY,
 222                         PGSQL_DIAG_SQLSTATE,
 223                         PGSQL_DIAG_MESSAGE_PRIMARY,
 224                         PGSQL_DIAG_MESSAGE_DETAIL,
 225                         PGSQL_DIAG_MESSAGE_HINT,
 226                         PGSQL_DIAG_STATEMENT_POSITION,
 227                         PGSQL_DIAG_INTERNAL_POSITION,
 228                         PGSQL_DIAG_INTERNAL_QUERY,
 229                         PGSQL_DIAG_CONTEXT,
 230                         PGSQL_DIAG_SOURCE_FILE,
 231                         PGSQL_DIAG_SOURCE_LINE,
 232                         PGSQL_DIAG_SOURCE_FUNCTION
 233                 ];
 234                 foreach ( $diags as $d ) {
 235                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 236                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 237                 }
 238         }
 239
 240         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 241                 if ( $tempIgnore ) {
 242                         /* Check for constraint violation */
 243                         if ( $errno === '23505' ) {
 244                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 245
 246                                 return;
 247                         }
 248                 }
 249                 /* Transaction stays in the ERROR state until rolled back */
 250                 if ( $this->mTrxLevel ) {
 251                         $this->rollback( __METHOD__ );
 252                 }
 253                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 254         }
 255
 256         public function freeResult( $res ) {
 257                 if ( $res instanceof ResultWrapper ) {
 258                         $res = $res->result;
 259                 }
 260                 MediaWiki\suppressWarnings();
 261                 $ok = pg_free_result( $res );
 262                 MediaWiki\restoreWarnings();
 263                 if ( !$ok ) {
 264                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 265                 }
 266         }
 267
 268         public function fetchObject( $res ) {
 269                 if ( $res instanceof ResultWrapper ) {
 270                         $res = $res->result;
 271                 }
 272                 MediaWiki\suppressWarnings();
 273                 $row = pg_fetch_object( $res );
 274                 MediaWiki\restoreWarnings();
 275                 # @todo FIXME: HACK HACK HACK HACK debug
 276
 277                 # @todo hashar: not sure if the following test really trigger if the object
 278                 #          fetching failed.
 279                 $conn = $this->getBindingHandle();
 280                 if ( pg_last_error( $conn ) ) {
 281                         throw new DBUnexpectedError(
 282                                 $this,
 283                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 284                         );
 285                 }
 286
 287                 return $row;
 288         }
 289
 290         public function fetchRow( $res ) {
 291                 if ( $res instanceof ResultWrapper ) {
 292                         $res = $res->result;
 293                 }
 294                 MediaWiki\suppressWarnings();
 295                 $row = pg_fetch_array( $res );
 296                 MediaWiki\restoreWarnings();
 297
 298                 $conn = $this->getBindingHandle();
 299                 if ( pg_last_error( $conn ) ) {
 300                         throw new DBUnexpectedError(
 301                                 $this,
 302                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 303                         );
 304                 }
 305
 306                 return $row;
 307         }
 308
 309         public function numRows( $res ) {
 310                 if ( $res instanceof ResultWrapper ) {
 311                         $res = $res->result;
 312                 }
 313                 MediaWiki\suppressWarnings();
 314                 $n = pg_num_rows( $res );
 315                 MediaWiki\restoreWarnings();
 316
 317                 $conn = $this->getBindingHandle();
 318                 if ( pg_last_error( $conn ) ) {
 319                         throw new DBUnexpectedError(
 320                                 $this,
 321                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 322                         );
 323                 }
 324
 325                 return $n;
 326         }
 327
 328         public function numFields( $res ) {
 329                 if ( $res instanceof ResultWrapper ) {
 330                         $res = $res->result;
 331                 }
 332
 333                 return pg_num_fields( $res );
 334         }
 335
 336         public function fieldName( $res, $n ) {
 337                 if ( $res instanceof ResultWrapper ) {
 338                         $res = $res->result;
 339                 }
 340
 341                 return pg_field_name( $res, $n );
 342         }
 343
 344         /**
 345          * Return the result of the last call to nextSequenceValue();
 346          * This must be called after nextSequenceValue().
 347          *
 348          * @return int|null
 349          */
 350         public function insertId() {
 351                 return $this->mInsertId;
 352         }
 353
 354         public function dataSeek( $res, $row ) {
 355                 if ( $res instanceof ResultWrapper ) {
 356                         $res = $res->result;
 357                 }
 358
 359                 return pg_result_seek( $res, $row );
 360         }
 361
 362         public function lastError() {
 363                 if ( $this->mConn ) {
 364                         if ( $this->mLastResult ) {
 365                                 return pg_result_error( $this->mLastResult );
 366                         } else {
 367                                 return pg_last_error();
 368                         }
 369                 }
 370
 371                 return $this->getLastPHPError() ?: 'No database connection';
 372         }
 373
 374         public function lastErrno() {
 375                 if ( $this->mLastResult ) {
 376                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 377                 } else {
 378                         return false;
 379                 }
 380         }
 381
 382         public function affectedRows() {
 383                 if ( !is_null( $this->mAffectedRows ) ) {
 384                         // Forced result for simulated queries
 385                         return $this->mAffectedRows;
 386                 }
 387                 if ( empty( $this->mLastResult ) ) {
 388                         return 0;
 389                 }
 390
 391                 return pg_affected_rows( $this->mLastResult );
 392         }
 393
 394         /**
 395          * Estimate rows in dataset
 396          * Returns estimated count, based on EXPLAIN output
 397          * This is not necessarily an accurate estimate, so use sparingly
 398          * Returns -1 if count cannot be found
 399          * Takes same arguments as Database::select()
 400          *
 401          * @param string $table
 402          * @param string $vars
 403          * @param string $conds
 404          * @param string $fname
 405          * @param array $options
 406          * @return int
 407          */
 408         public function estimateRowCount( $table, $vars = '*', $conds = '',
 409                 $fname = __METHOD__, $options = []
 410         ) {
 411                 $options['EXPLAIN'] = true;
 412                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 413                 $rows = -1;
 414                 if ( $res ) {
 415                         $row = $this->fetchRow( $res );
 416                         $count = [];
 417                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 418                                 $rows = (int)$count[1];
 419                         }
 420                 }
 421
 422                 return $rows;
 423         }
 424
 425         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 426                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 427                 $res = $this->query( $sql, $fname );
 428                 if ( !$res ) {
 429                         return null;
 430                 }
 431                 foreach ( $res as $row ) {
 432                         if ( $row->indexname == $this->indexName( $index ) ) {
 433                                 return $row;
 434                         }
 435                 }
 436
 437                 return false;
 438         }
 439
 440         public function indexAttributes( $index, $schema = false ) {
 441                 if ( $schema === false ) {
 442                         $schema = $this->getCoreSchema();
 443                 }
 444                 /*
 445                  * A subquery would be not needed if we didn't care about the order
 446                  * of attributes, but we do
 447                  */
 448                 $sql = <<<__INDEXATTR__
 449
 450                         SELECT opcname,
 451                                 attname,
 452                                 i.indoption[s.g] as option,
 453                                 pg_am.amname
 454                         FROM
 455                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 456                                         FROM
 457                                                 pg_index isub
 458                                         JOIN pg_class cis
 459                                                 ON cis.oid=isub.indexrelid
 460                                         JOIN pg_namespace ns
 461                                                 ON cis.relnamespace = ns.oid
 462                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 463                                 pg_attribute,
 464                                 pg_opclass opcls,
 465                                 pg_am,
 466                                 pg_class ci
 467                                 JOIN pg_index i
 468                                         ON ci.oid=i.indexrelid
 469                                 JOIN pg_class ct
 470                                         ON ct.oid = i.indrelid
 471                                 JOIN pg_namespace n
 472                                         ON ci.relnamespace = n.oid
 473                                 WHERE
 474                                         ci.relname='$index' AND n.nspname='$schema'
 475                                         AND     attrelid = ct.oid
 476                                         AND     i.indkey[s.g] = attnum
 477                                         AND     i.indclass[s.g] = opcls.oid
 478                                         AND     pg_am.oid = opcls.opcmethod
 479 __INDEXATTR__;
 480                 $res = $this->query( $sql, __METHOD__ );
 481                 $a = [];
 482                 if ( $res ) {
 483                         foreach ( $res as $row ) {
 484                                 $a[] = [
 485                                         $row->attname,
 486                                         $row->opcname,
 487                                         $row->amname,
 488                                         $row->option ];
 489                         }
 490                 } else {
 491                         return null;
 492                 }
 493
 494                 return $a;
 495         }
 496
 497         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 498                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 499                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 500                         $this->strencode( $this->indexName( $index ) ) .
 501                         ")'";
 502                 $res = $this->query( $sql, $fname );
 503                 if ( !$res ) {
 504                         return null;
 505                 }
 506
 507                 return $res->numRows() > 0;
 508         }
 509
 510         public function selectSQLText(
 511                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 512         ) {
 513                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 514                 // to the parent function to get the actual SQL text.
 515                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 516                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 517                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 518                 // accordingly.
 519                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 520                 if ( is_array( $options ) ) {
 521                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 522                         if ( $forUpdateKey !== false && $join_conds ) {
 523                                 unset( $options[$forUpdateKey] );
 524
 525                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 526                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 527                                                 $options['FOR UPDATE'][] = $table_cond;
 528                                         }
 529                                 }
 530                         }
 531
 532                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 533                                 unset( $options['ORDER BY'] );
 534                         }
 535                 }
 536
 537                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 538         }
 539
 540         /**
 541          * INSERT wrapper, inserts an array into a table
 542          *
 543          * $args may be a single associative array, or an array of these with numeric keys,
 544          * for multi-row insert (Postgres version 8.2 and above only).
 545          *
 546          * @param string $table Name of the table to insert to.
 547          * @param array $args Items to insert into the table.
 548          * @param string $fname Name of the function, for profiling
 549          * @param array|string $options String or array. Valid options: IGNORE
 550          * @return bool Success of insert operation. IGNORE always returns true.
 551          */
 552         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 553                 if ( !count( $args ) ) {
 554                         return true;
 555                 }
 556
 557                 $table = $this->tableName( $table );
 558                 if ( !isset( $this->numericVersion ) ) {
 559                         $this->getServerVersion();
 560                 }
 561
 562                 if ( !is_array( $options ) ) {
 563                         $options = [ $options ];
 564                 }
 565
 566                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 567                         $multi = true;
 568                         $keys = array_keys( $args[0] );
 569                 } else {
 570                         $multi = false;
 571                         $keys = array_keys( $args );
 572                 }
 573
 574                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 575                 $savepoint = $olde = null;
 576                 $numrowsinserted = 0;
 577                 if ( in_array( 'IGNORE', $options ) ) {
 578                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 579                         $olde = error_reporting( 0 );
 580                         // For future use, we may want to track the number of actual inserts
 581                         // Right now, insert (all writes) simply return true/false
 582                 }
 583
 584                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 585
 586                 if ( $multi ) {
 587                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 588                                 $first = true;
 589                                 foreach ( $args as $row ) {
 590                                         if ( $first ) {
 591                                                 $first = false;
 592                                         } else {
 593                                                 $sql .= ',';
 594                                         }
 595                                         $sql .= '(' . $this->makeList( $row ) . ')';
 596                                 }
 597                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 598                         } else {
 599                                 $res = true;
 600                                 $origsql = $sql;
 601                                 foreach ( $args as $row ) {
 602                                         $tempsql = $origsql;
 603                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 604
 605                                         if ( $savepoint ) {
 606                                                 $savepoint->savepoint();
 607                                         }
 608
 609                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 610
 611                                         if ( $savepoint ) {
 612                                                 $bar = pg_result_error( $this->mLastResult );
 613                                                 if ( $bar != false ) {
 614                                                         $savepoint->rollback();
 615                                                 } else {
 616                                                         $savepoint->release();
 617                                                         $numrowsinserted++;
 618                                                 }
 619                                         }
 620
 621                                         // If any of them fail, we fail overall for this function call
 622                                         // Note that this will be ignored if IGNORE is set
 623                                         if ( !$tempres ) {
 624                                                 $res = false;
 625                                         }
 626                                 }
 627                         }
 628                 } else {
 629                         // Not multi, just a lone insert
 630                         if ( $savepoint ) {
 631                                 $savepoint->savepoint();
 632                         }
 633
 634                         $sql .= '(' . $this->makeList( $args ) . ')';
 635                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 636                         if ( $savepoint ) {
 637                                 $bar = pg_result_error( $this->mLastResult );
 638                                 if ( $bar != false ) {
 639                                         $savepoint->rollback();
 640                                 } else {
 641                                         $savepoint->release();
 642                                         $numrowsinserted++;
 643                                 }
 644                         }
 645                 }
 646                 if ( $savepoint ) {
 647                         error_reporting( $olde );
 648                         $savepoint->commit();
 649
 650                         // Set the affected row count for the whole operation
 651                         $this->mAffectedRows = $numrowsinserted;
 652
 653                         // IGNORE always returns true
 654                         return true;
 655                 }
 656
 657                 return $res;
 658         }
 659
 660         /**
 661          * INSERT SELECT wrapper
 662          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 663          * Source items may be literals rather then field names, but strings should
 664          * be quoted with Database::addQuotes()
 665          * $conds may be "*" to copy the whole table
 666          * srcTable may be an array of tables.
 667          * @todo FIXME: Implement this a little better (seperate select/insert)?
 668          *
 669          * @param string $destTable
 670          * @param array|string $srcTable
 671          * @param array $varMap
 672          * @param array $conds
 673          * @param string $fname
 674          * @param array $insertOptions
 675          * @param array $selectOptions
 676          * @return bool
 677          */
 678         public function nativeInsertSelect(
 679                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 680                 $insertOptions = [], $selectOptions = []
 681         ) {
 682                 $destTable = $this->tableName( $destTable );
 683
 684                 if ( !is_array( $insertOptions ) ) {
 685                         $insertOptions = [ $insertOptions ];
 686                 }
 687
 688                 /*
 689                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 690                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 691                  */
 692                 $savepoint = $olde = null;
 693                 $numrowsinserted = 0;
 694                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 695                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 696                         $olde = error_reporting( 0 );
 697                         $savepoint->savepoint();
 698                 }
 699
 700                 if ( !is_array( $selectOptions ) ) {
 701                         $selectOptions = [ $selectOptions ];
 702                 }
 703                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 704                         $this->makeSelectOptions( $selectOptions );
 705                 if ( is_array( $srcTable ) ) {
 706                         $srcTable = implode( ',', array_map( [ $this, 'tableName' ], $srcTable ) );
 707                 } else {
 708                         $srcTable = $this->tableName( $srcTable );
 709                 }
 710
 711                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 712                         " SELECT $startOpts " . implode( ',', $varMap ) .
 713                         " FROM $srcTable $useIndex $ignoreIndex ";
 714
 715                 if ( $conds != '*' ) {
 716                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 717                 }
 718
 719                 $sql .= " $tailOpts";
 720
 721                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 722                 if ( $savepoint ) {
 723                         $bar = pg_result_error( $this->mLastResult );
 724                         if ( $bar != false ) {
 725                                 $savepoint->rollback();
 726                         } else {
 727                                 $savepoint->release();
 728                                 $numrowsinserted++;
 729                         }
 730                         error_reporting( $olde );
 731                         $savepoint->commit();
 732
 733                         // Set the affected row count for the whole operation
 734                         $this->mAffectedRows = $numrowsinserted;
 735
 736                         // IGNORE always returns true
 737                         return true;
 738                 }
 739
 740                 return $res;
 741         }
 742
 743         public function tableName( $name, $format = 'quoted' ) {
 744                 // Replace reserved words with better ones
 745                 $name = $this->remappedTableName( $name );
 746
 747                 return parent::tableName( $name, $format );
 748         }
 749
 750         /**
 751          * @param string $name
 752          * @return string Value of $name or remapped name if $name is a reserved keyword
 753          */
 754         public function remappedTableName( $name ) {
 755                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 756         }
 757
 758         /**
 759          * @param string $name
 760          * @param string $format
 761          * @return string Qualified and encoded (if requested) table name
 762          */
 763         public function realTableName( $name, $format = 'quoted' ) {
 764                 return parent::tableName( $name, $format );
 765         }
 766
 767         public function nextSequenceValue( $seqName ) {
 768                 $safeseq = str_replace( "'", "''", $seqName );
 769                 $res = $this->query( "SELECT nextval('$safeseq')" );
 770                 $row = $this->fetchRow( $res );
 771                 $this->mInsertId = $row[0];
 772
 773                 return $this->mInsertId;
 774         }
 775
 776         /**
 777          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 778          *
 779          * @param string $seqName
 780          * @return int
 781          */
 782         public function currentSequenceValue( $seqName ) {
 783                 $safeseq = str_replace( "'", "''", $seqName );
 784                 $res = $this->query( "SELECT currval('$safeseq')" );
 785                 $row = $this->fetchRow( $res );
 786                 $currval = $row[0];
 787
 788                 return $currval;
 789         }
 790
 791         public function textFieldSize( $table, $field ) {
 792                 $table = $this->tableName( $table );
 793                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 794                         FROM pg_class c, pg_attribute a, pg_type t
 795                         WHERE relname='$table' AND a.attrelid=c.oid AND
 796                                 a.atttypid=t.oid and a.attname='$field'";
 797                 $res = $this->query( $sql );
 798                 $row = $this->fetchObject( $res );
 799                 if ( $row->ftype == 'varchar' ) {
 800                         $size = $row->size - 4;
 801                 } else {
 802                         $size = $row->size;
 803                 }
 804
 805                 return $size;
 806         }
 807
 808         public function limitResult( $sql, $limit, $offset = false ) {
 809                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 810         }
 811
 812         public function wasDeadlock() {
 813                 return $this->lastErrno() == '40P01';
 814         }
 815
 816         public function duplicateTableStructure(
 817                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 818         ) {
 819                 $newName = $this->addIdentifierQuotes( $newName );
 820                 $oldName = $this->addIdentifierQuotes( $oldName );
 821
 822                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 823                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 824         }
 825
 826         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 827                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 828                 $result = $this->query(
 829                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 830                 $endArray = [];
 831
 832                 foreach ( $result as $table ) {
 833                         $vars = get_object_vars( $table );
 834                         $table = array_pop( $vars );
 835                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 836                                 $endArray[] = $table;
 837                         }
 838                 }
 839
 840                 return $endArray;
 841         }
 842
 843         public function timestamp( $ts = 0 ) {
 844                 $ct = new ConvertibleTimestamp( $ts );
 845
 846                 return $ct->getTimestamp( TS_POSTGRES );
 847         }
 848
 849         /**
 850          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 851          * to https://secure.php.net/manual/en/ref.pgsql.php
 852          *
 853          * Parsing a postgres array can be a tricky problem, he's my
 854          * take on this, it handles multi-dimensional arrays plus
 855          * escaping using a nasty regexp to determine the limits of each
 856          * data-item.
 857          *
 858          * This should really be handled by PHP PostgreSQL module
 859          *
 860          * @since 1.19
 861          * @param string $text Postgreql array returned in a text form like {a,b}
 862          * @param string[] $output
 863          * @param int|bool $limit
 864          * @param int $offset
 865          * @return string[]
 866          */
 867         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 868                 if ( false === $limit ) {
 869                         $limit = strlen( $text ) - 1;
 870                         $output = [];
 871                 }
 872                 if ( '{}' == $text ) {
 873                         return $output;
 874                 }
 875                 do {
 876                         if ( '{' != $text[$offset] ) {
 877                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 878                                         $text, $match, 0, $offset );
 879                                 $offset += strlen( $match[0] );
 880                                 $output[] = ( '"' != $match[1][0]
 881                                         ? $match[1]
 882                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 883                                 if ( '},' == $match[3] ) {
 884                                         return $output;
 885                                 }
 886                         } else {
 887                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 888                         }
 889                 } while ( $limit > $offset );
 890
 891                 return $output;
 892         }
 893
 894         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 895                 return $valuedata;
 896         }
 897
 898         public function getSoftwareLink() {
 899                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 900         }
 901
 902         /**
 903          * Return current schema (executes SELECT current_schema())
 904          * Needs transaction
 905          *
 906          * @since 1.19
 907          * @return string Default schema for the current session
 908          */
 909         public function getCurrentSchema() {
 910                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 911                 $row = $this->fetchRow( $res );
 912
 913                 return $row[0];
 914         }
 915
 916         /**
 917          * Return list of schemas which are accessible without schema name
 918          * This is list does not contain magic keywords like "$user"
 919          * Needs transaction
 920          *
 921          * @see getSearchPath()
 922          * @see setSearchPath()
 923          * @since 1.19
 924          * @return array List of actual schemas for the current sesson
 925          */
 926         public function getSchemas() {
 927                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 928                 $row = $this->fetchRow( $res );
 929                 $schemas = [];
 930
 931                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 932
 933                 return $this->pg_array_parse( $row[0], $schemas );
 934         }
 935
 936         /**
 937          * Return search patch for schemas
 938          * This is different from getSchemas() since it contain magic keywords
 939          * (like "$user").
 940          * Needs transaction
 941          *
 942          * @since 1.19
 943          * @return array How to search for table names schemas for the current user
 944          */
 945         public function getSearchPath() {
 946                 $res = $this->query( "SHOW search_path", __METHOD__ );
 947                 $row = $this->fetchRow( $res );
 948
 949                 /* PostgreSQL returns SHOW values as strings */
 950
 951                 return explode( ",", $row[0] );
 952         }
 953
 954         /**
 955          * Update search_path, values should already be sanitized
 956          * Values may contain magic keywords like "$user"
 957          * @since 1.19
 958          *
 959          * @param array $search_path List of schemas to be searched by default
 960          */
 961         private function setSearchPath( $search_path ) {
 962                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 963         }
 964
 965         /**
 966          * Determine default schema for the current application
 967          * Adjust this session schema search path if desired schema exists
 968          * and is not alread there.
 969          *
 970          * We need to have name of the core schema stored to be able
 971          * to query database metadata.
 972          *
 973          * This will be also called by the installer after the schema is created
 974          *
 975          * @since 1.19
 976          *
 977          * @param string $desiredSchema
 978          */
 979         public function determineCoreSchema( $desiredSchema ) {
 980                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 981                 if ( $this->schemaExists( $desiredSchema ) ) {
 982                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 983                                 $this->mCoreSchema = $desiredSchema;
 984                                 $this->queryLogger->debug(
 985                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 986                         } else {
 987                                 /**
 988                                  * Prepend our schema (e.g. 'mediawiki') in front
 989                                  * of the search path
 990                                  * Fixes T17816
 991                                  */
 992                                 $search_path = $this->getSearchPath();
 993                                 array_unshift( $search_path,
 994                                         $this->addIdentifierQuotes( $desiredSchema ) );
 995                                 $this->setSearchPath( $search_path );
 996                                 $this->mCoreSchema = $desiredSchema;
 997                                 $this->queryLogger->debug(
 998                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 999                         }
1000                 } else {
1001                         $this->mCoreSchema = $this->getCurrentSchema();
1002                         $this->queryLogger->debug(
1003                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1004                                 $this->mCoreSchema . "\"\n" );
1005                 }
1006                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1007                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1008         }
1009
1010         /**
1011          * Return schema name for core application tables
1012          *
1013          * @since 1.19
1014          * @return string Core schema name
1015          */
1016         public function getCoreSchema() {
1017                 return $this->mCoreSchema;
1018         }
1019
1020         public function getServerVersion() {
1021                 if ( !isset( $this->numericVersion ) ) {
1022                         $conn = $this->getBindingHandle();
1023                         $versionInfo = pg_version( $conn );
1024                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1025                                 // Old client, abort install
1026                                 $this->numericVersion = '7.3 or earlier';
1027                         } elseif ( isset( $versionInfo['server'] ) ) {
1028                                 // Normal client
1029                                 $this->numericVersion = $versionInfo['server'];
1030                         } else {
1031                                 // T18937: broken pgsql extension from PHP<5.3
1032                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1033                         }
1034                 }
1035
1036                 return $this->numericVersion;
1037         }
1038
1039         /**
1040          * Query whether a given relation exists (in the given schema, or the
1041          * default mw one if not given)
1042          * @param string $table
1043          * @param array|string $types
1044          * @param bool|string $schema
1045          * @return bool
1046          */
1047         private function relationExists( $table, $types, $schema = false ) {
1048                 if ( !is_array( $types ) ) {
1049                         $types = [ $types ];
1050                 }
1051                 if ( $schema === false ) {
1052                         $schema = $this->getCoreSchema();
1053                 }
1054                 $etable = $this->addQuotes( $table );
1055                 $eschema = $this->addQuotes( $schema );
1056                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1057                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1058                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1059                 $res = $this->query( $sql );
1060                 $count = $res ? $res->numRows() : 0;
1061
1062                 return (bool)$count;
1063         }
1064
1065         /**
1066          * For backward compatibility, this function checks both tables and views.
1067          * @param string $table
1068          * @param string $fname
1069          * @param bool|string $schema
1070          * @return bool
1071          */
1072         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1073                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1074         }
1075
1076         public function sequenceExists( $sequence, $schema = false ) {
1077                 return $this->relationExists( $sequence, 'S', $schema );
1078         }
1079
1080         public function triggerExists( $table, $trigger ) {
1081                 $q = <<<SQL
1082         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1083                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1084                         AND tgrelid=pg_class.oid
1085                         AND nspname=%s AND relname=%s AND tgname=%s
1086 SQL;
1087                 $res = $this->query(
1088                         sprintf(
1089                                 $q,
1090                                 $this->addQuotes( $this->getCoreSchema() ),
1091                                 $this->addQuotes( $table ),
1092                                 $this->addQuotes( $trigger )
1093                         )
1094                 );
1095                 if ( !$res ) {
1096                         return null;
1097                 }
1098                 $rows = $res->numRows();
1099
1100                 return $rows;
1101         }
1102
1103         public function ruleExists( $table, $rule ) {
1104                 $exists = $this->selectField( 'pg_rules', 'rulename',
1105                         [
1106                                 'rulename' => $rule,
1107                                 'tablename' => $table,
1108                                 'schemaname' => $this->getCoreSchema()
1109                         ]
1110                 );
1111
1112                 return $exists === $rule;
1113         }
1114
1115         public function constraintExists( $table, $constraint ) {
1116                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1117                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1118                         $this->addQuotes( $this->getCoreSchema() ),
1119                         $this->addQuotes( $table ),
1120                         $this->addQuotes( $constraint )
1121                 );
1122                 $res = $this->query( $sql );
1123                 if ( !$res ) {
1124                         return null;
1125                 }
1126                 $rows = $res->numRows();
1127
1128                 return $rows;
1129         }
1130
1131         /**
1132          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1133          * @param string $schema
1134          * @return bool
1135          */
1136         public function schemaExists( $schema ) {
1137                 if ( !strlen( $schema ) ) {
1138                         return false; // short-circuit
1139                 }
1140
1141                 $exists = $this->selectField(
1142                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1143
1144                 return (bool)$exists;
1145         }
1146
1147         /**
1148          * Returns true if a given role (i.e. user) exists, false otherwise.
1149          * @param string $roleName
1150          * @return bool
1151          */
1152         public function roleExists( $roleName ) {
1153                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1154                         [ 'rolname' => $roleName ], __METHOD__ );
1155
1156                 return (bool)$exists;
1157         }
1158
1159         /**
1160          * @var string $table
1161          * @var string $field
1162          * @return PostgresField|null
1163          */
1164         public function fieldInfo( $table, $field ) {
1165                 return PostgresField::fromText( $this, $table, $field );
1166         }
1167
1168         /**
1169          * pg_field_type() wrapper
1170          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1171          * @param int $index Field number, starting from 0
1172          * @return string
1173          */
1174         public function fieldType( $res, $index ) {
1175                 if ( $res instanceof ResultWrapper ) {
1176                         $res = $res->result;
1177                 }
1178
1179                 return pg_field_type( $res, $index );
1180         }
1181
1182         public function encodeBlob( $b ) {
1183                 return new PostgresBlob( pg_escape_bytea( $b ) );
1184         }
1185
1186         public function decodeBlob( $b ) {
1187                 if ( $b instanceof PostgresBlob ) {
1188                         $b = $b->fetch();
1189                 } elseif ( $b instanceof Blob ) {
1190                         return $b->fetch();
1191                 }
1192
1193                 return pg_unescape_bytea( $b );
1194         }
1195
1196         public function strencode( $s ) {
1197                 // Should not be called by us
1198                 return pg_escape_string( $this->getBindingHandle(), $s );
1199         }
1200
1201         public function addQuotes( $s ) {
1202                 $conn = $this->getBindingHandle();
1203
1204                 if ( is_null( $s ) ) {
1205                         return 'NULL';
1206                 } elseif ( is_bool( $s ) ) {
1207                         return intval( $s );
1208                 } elseif ( $s instanceof Blob ) {
1209                         if ( $s instanceof PostgresBlob ) {
1210                                 $s = $s->fetch();
1211                         } else {
1212                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1213                         }
1214                         return "'$s'";
1215                 }
1216
1217                 return "'" . pg_escape_string( $conn, $s ) . "'";
1218         }
1219
1220         /**
1221          * Postgres specific version of replaceVars.
1222          * Calls the parent version in Database.php
1223          *
1224          * @param string $ins SQL string, read from a stream (usually tables.sql)
1225          * @return string SQL string
1226          */
1227         protected function replaceVars( $ins ) {
1228                 $ins = parent::replaceVars( $ins );
1229
1230                 if ( $this->numericVersion >= 8.3 ) {
1231                         // Thanks for not providing backwards-compatibility, 8.3
1232                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1233                 }
1234
1235                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1236                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1237                 }
1238
1239                 return $ins;
1240         }
1241
1242         public function makeSelectOptions( $options ) {
1243                 $preLimitTail = $postLimitTail = '';
1244                 $startOpts = $useIndex = $ignoreIndex = '';
1245
1246                 $noKeyOptions = [];
1247                 foreach ( $options as $key => $option ) {
1248                         if ( is_numeric( $key ) ) {
1249                                 $noKeyOptions[$option] = true;
1250                         }
1251                 }
1252
1253                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1254
1255                 $preLimitTail .= $this->makeOrderBy( $options );
1256
1257                 if ( isset( $options['FOR UPDATE'] ) ) {
1258                         $postLimitTail .= ' FOR UPDATE OF ' .
1259                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1260                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1261                         $postLimitTail .= ' FOR UPDATE';
1262                 }
1263
1264                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1265                         $startOpts .= 'DISTINCT';
1266                 }
1267
1268                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1269         }
1270
1271         public function getDBname() {
1272                 return $this->mDBname;
1273         }
1274
1275         public function getServer() {
1276                 return $this->mServer;
1277         }
1278
1279         public function buildConcat( $stringList ) {
1280                 return implode( ' || ', $stringList );
1281         }
1282
1283         public function buildGroupConcatField(
1284                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1285         ) {
1286                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1287
1288                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1289         }
1290
1291         public function buildStringCast( $field ) {
1292                 return $field . '::text';
1293         }
1294
1295         public function streamStatementEnd( &$sql, &$newLine ) {
1296                 # Allow dollar quoting for function declarations
1297                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1298                         if ( $this->delimiter ) {
1299                                 $this->delimiter = false;
1300                         } else {
1301                                 $this->delimiter = ';';
1302                         }
1303                 }
1304
1305                 return parent::streamStatementEnd( $sql, $newLine );
1306         }
1307
1308         public function doLockTables( array $read, array $write, $method ) {
1309                 $tablesWrite = [];
1310                 foreach ( $write as $table ) {
1311                         $tablesWrite[] = $this->tableName( $table );
1312                 }
1313                 $tablesRead = [];
1314                 foreach ( $read as $table ) {
1315                         $tablesRead[] = $this->tableName( $table );
1316                 }
1317
1318                 // Acquire locks for the duration of the current transaction...
1319                 if ( $tablesWrite ) {
1320                         $this->query(
1321                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1322                                 $method
1323                         );
1324                 }
1325                 if ( $tablesRead ) {
1326                         $this->query(
1327                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1328                                 $method
1329                         );
1330                 }
1331
1332                 return true;
1333         }
1334
1335         public function lockIsFree( $lockName, $method ) {
1336                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1337                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1338                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1339                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1340                 $row = $this->fetchObject( $result );
1341
1342                 return ( $row->lockstatus === 't' );
1343         }
1344
1345         public function lock( $lockName, $method, $timeout = 5 ) {
1346                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1347                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1348                 $loop = new WaitConditionLoop(
1349                         function () use ( $lockName, $key, $timeout, $method ) {
1350                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1351                                 $row = $this->fetchObject( $res );
1352                                 if ( $row->lockstatus === 't' ) {
1353                                         parent::lock( $lockName, $method, $timeout ); // record
1354                                         return true;
1355                                 }
1356
1357                                 return WaitConditionLoop::CONDITION_CONTINUE;
1358                         },
1359                         $timeout
1360                 );
1361
1362                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1363         }
1364
1365         public function unlock( $lockName, $method ) {
1366                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1367                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1368                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1369                 $row = $this->fetchObject( $result );
1370
1371                 if ( $row->lockstatus === 't' ) {
1372                         parent::unlock( $lockName, $method ); // record
1373                         return true;
1374                 }
1375
1376                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1377
1378                 return false;
1379         }
1380
1381         /**
1382          * @param string $lockName
1383          * @return string Integer
1384          */
1385         private function bigintFromLockName( $lockName ) {
1386                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1387         }
1388 }
1389
1390 class_alias( DatabasePostgres::class, 'DatabasePostgres' );