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 Wikimedia;
  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 $lastResultHandle = null;
  39         /** @var int The number of rows affected as an integer */
  40         protected $lastAffectedRowCount = null;
  41
  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 $coreSchema;
  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->server = $server;
 101                 $this->user = $user;
 102                 $this->password = $password;
 103                 $this->dbName = $dbName;
 104
 105                 $connectVars = [
 106                         // pg_connect() user $user as the default database. Since a database is *required*,
 107                         // at least pick a "don't care" database that is more likely to exist. This case
 108                         // arrises when LoadBalancer::getConnection( $i, [], '' ) is used.
 109                         'dbname' => strlen( $dbName ) ? $dbName : 'postgres',
 110                         'user' => $user,
 111                         'password' => $password
 112                 ];
 113                 if ( $server != false && $server != '' ) {
 114                         $connectVars['host'] = $server;
 115                 }
 116                 if ( (int)$this->port > 0 ) {
 117                         $connectVars['port'] = (int)$this->port;
 118                 }
 119                 if ( $this->flags & self::DBO_SSL ) {
 120                         $connectVars['sslmode'] = 1;
 121                 }
 122
 123                 $this->connectString = $this->makeConnectionString( $connectVars );
 124                 $this->close();
 125                 $this->installErrorHandler();
 126
 127                 try {
 128                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 129                         $this->conn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 130                 } catch ( Exception $ex ) {
 131                         $this->restoreErrorHandler();
 132                         throw $ex;
 133                 }
 134
 135                 $phpError = $this->restoreErrorHandler();
 136
 137                 if ( !$this->conn ) {
 138                         $this->queryLogger->debug(
 139                                 "DB connection error\n" .
 140                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 141                                 substr( $password, 0, 3 ) . "...\n"
 142                         );
 143                         $this->queryLogger->debug( $this->lastError() . "\n" );
 144                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 145                 }
 146
 147                 $this->opened = true;
 148
 149                 # If called from the command-line (e.g. importDump), only show errors
 150                 if ( $this->cliMode ) {
 151                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 152                 }
 153
 154                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 155                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 156                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 157                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 158                 if ( $this->getServerVersion() >= 9.0 ) {
 159                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 160                 }
 161
 162                 $this->determineCoreSchema( $this->schema );
 163                 // The schema to be used is now in the search path; no need for explicit qualification
 164                 $this->schema = '';
 165
 166                 return $this->conn;
 167         }
 168
 169         public function databasesAreIndependent() {
 170                 return true;
 171         }
 172
 173         /**
 174          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 175          * DB name doesn't match the open connection, open a new one
 176          * @param string $db
 177          * @return bool
 178          * @throws DBUnexpectedError
 179          */
 180         public function selectDB( $db ) {
 181                 if ( $this->dbName !== $db ) {
 182                         return (bool)$this->open( $this->server, $this->user, $this->password, $db );
 183                 } else {
 184                         return true;
 185                 }
 186         }
 187
 188         /**
 189          * @param string[] $vars
 190          * @return string
 191          */
 192         private function makeConnectionString( $vars ) {
 193                 $s = '';
 194                 foreach ( $vars as $name => $value ) {
 195                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 196                 }
 197
 198                 return $s;
 199         }
 200
 201         protected function closeConnection() {
 202                 return $this->conn ? pg_close( $this->conn ) : true;
 203         }
 204
 205         protected function isTransactableQuery( $sql ) {
 206                 return parent::isTransactableQuery( $sql ) &&
 207                         !preg_match( '/^SELECT\s+pg_(try_|)advisory_\w+\(/', $sql );
 208         }
 209
 210         public function doQuery( $sql ) {
 211                 $conn = $this->getBindingHandle();
 212
 213                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 214                 // Clear previously left over PQresult
 215                 while ( $res = pg_get_result( $conn ) ) {
 216                         pg_free_result( $res );
 217                 }
 218                 if ( pg_send_query( $conn, $sql ) === false ) {
 219                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 220                 }
 221                 $this->lastResultHandle = pg_get_result( $conn );
 222                 $this->lastAffectedRowCount = null;
 223                 if ( pg_result_error( $this->lastResultHandle ) ) {
 224                         return false;
 225                 }
 226
 227                 return $this->lastResultHandle;
 228         }
 229
 230         protected function dumpError() {
 231                 $diags = [
 232                         PGSQL_DIAG_SEVERITY,
 233                         PGSQL_DIAG_SQLSTATE,
 234                         PGSQL_DIAG_MESSAGE_PRIMARY,
 235                         PGSQL_DIAG_MESSAGE_DETAIL,
 236                         PGSQL_DIAG_MESSAGE_HINT,
 237                         PGSQL_DIAG_STATEMENT_POSITION,
 238                         PGSQL_DIAG_INTERNAL_POSITION,
 239                         PGSQL_DIAG_INTERNAL_QUERY,
 240                         PGSQL_DIAG_CONTEXT,
 241                         PGSQL_DIAG_SOURCE_FILE,
 242                         PGSQL_DIAG_SOURCE_LINE,
 243                         PGSQL_DIAG_SOURCE_FUNCTION
 244                 ];
 245                 foreach ( $diags as $d ) {
 246                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 247                                 $d, pg_result_error_field( $this->lastResultHandle, $d ) ) );
 248                 }
 249         }
 250
 251         public function freeResult( $res ) {
 252                 if ( $res instanceof ResultWrapper ) {
 253                         $res = $res->result;
 254                 }
 255                 Wikimedia\suppressWarnings();
 256                 $ok = pg_free_result( $res );
 257                 Wikimedia\restoreWarnings();
 258                 if ( !$ok ) {
 259                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 260                 }
 261         }
 262
 263         public function fetchObject( $res ) {
 264                 if ( $res instanceof ResultWrapper ) {
 265                         $res = $res->result;
 266                 }
 267                 Wikimedia\suppressWarnings();
 268                 $row = pg_fetch_object( $res );
 269                 Wikimedia\restoreWarnings();
 270                 # @todo FIXME: HACK HACK HACK HACK debug
 271
 272                 # @todo hashar: not sure if the following test really trigger if the object
 273                 #          fetching failed.
 274                 $conn = $this->getBindingHandle();
 275                 if ( pg_last_error( $conn ) ) {
 276                         throw new DBUnexpectedError(
 277                                 $this,
 278                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 279                         );
 280                 }
 281
 282                 return $row;
 283         }
 284
 285         public function fetchRow( $res ) {
 286                 if ( $res instanceof ResultWrapper ) {
 287                         $res = $res->result;
 288                 }
 289                 Wikimedia\suppressWarnings();
 290                 $row = pg_fetch_array( $res );
 291                 Wikimedia\restoreWarnings();
 292
 293                 $conn = $this->getBindingHandle();
 294                 if ( pg_last_error( $conn ) ) {
 295                         throw new DBUnexpectedError(
 296                                 $this,
 297                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 298                         );
 299                 }
 300
 301                 return $row;
 302         }
 303
 304         public function numRows( $res ) {
 305                 if ( $res instanceof ResultWrapper ) {
 306                         $res = $res->result;
 307                 }
 308                 Wikimedia\suppressWarnings();
 309                 $n = pg_num_rows( $res );
 310                 Wikimedia\restoreWarnings();
 311
 312                 $conn = $this->getBindingHandle();
 313                 if ( pg_last_error( $conn ) ) {
 314                         throw new DBUnexpectedError(
 315                                 $this,
 316                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 317                         );
 318                 }
 319
 320                 return $n;
 321         }
 322
 323         public function numFields( $res ) {
 324                 if ( $res instanceof ResultWrapper ) {
 325                         $res = $res->result;
 326                 }
 327
 328                 return pg_num_fields( $res );
 329         }
 330
 331         public function fieldName( $res, $n ) {
 332                 if ( $res instanceof ResultWrapper ) {
 333                         $res = $res->result;
 334                 }
 335
 336                 return pg_field_name( $res, $n );
 337         }
 338
 339         public function insertId() {
 340                 $res = $this->query( "SELECT lastval()" );
 341                 $row = $this->fetchRow( $res );
 342                 return is_null( $row[0] ) ? null : (int)$row[0];
 343         }
 344
 345         public function dataSeek( $res, $row ) {
 346                 if ( $res instanceof ResultWrapper ) {
 347                         $res = $res->result;
 348                 }
 349
 350                 return pg_result_seek( $res, $row );
 351         }
 352
 353         public function lastError() {
 354                 if ( $this->conn ) {
 355                         if ( $this->lastResultHandle ) {
 356                                 return pg_result_error( $this->lastResultHandle );
 357                         } else {
 358                                 return pg_last_error();
 359                         }
 360                 }
 361
 362                 return $this->getLastPHPError() ?: 'No database connection';
 363         }
 364
 365         public function lastErrno() {
 366                 if ( $this->lastResultHandle ) {
 367                         return pg_result_error_field( $this->lastResultHandle, PGSQL_DIAG_SQLSTATE );
 368                 } else {
 369                         return false;
 370                 }
 371         }
 372
 373         protected function fetchAffectedRowCount() {
 374                 if ( !is_null( $this->lastAffectedRowCount ) ) {
 375                         // Forced result for simulated queries
 376                         return $this->lastAffectedRowCount;
 377                 }
 378                 if ( !$this->lastResultHandle ) {
 379                         return 0;
 380                 }
 381
 382                 return pg_affected_rows( $this->lastResultHandle );
 383         }
 384
 385         /**
 386          * Estimate rows in dataset
 387          * Returns estimated count, based on EXPLAIN output
 388          * This is not necessarily an accurate estimate, so use sparingly
 389          * Returns -1 if count cannot be found
 390          * Takes same arguments as Database::select()
 391          *
 392          * @param string $table
 393          * @param string $var
 394          * @param string $conds
 395          * @param string $fname
 396          * @param array $options
 397          * @param array $join_conds
 398          * @return int
 399          */
 400         public function estimateRowCount( $table, $var = '*', $conds = '',
 401                 $fname = __METHOD__, $options = [], $join_conds = []
 402         ) {
 403                 $conds = $this->normalizeConditions( $conds, $fname );
 404                 $column = $this->extractSingleFieldFromList( $var );
 405                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 406                         $conds[] = "$column IS NOT NULL";
 407                 }
 408
 409                 $options['EXPLAIN'] = true;
 410                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 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                 if ( is_string( $options ) ) {
 512                         $options = [ $options ];
 513                 }
 514
 515                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 516                 // to the parent function to get the actual SQL text.
 517                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 518                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 519                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 520                 // accordingly.
 521                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 522                 if ( is_array( $options ) ) {
 523                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 524                         if ( $forUpdateKey !== false && $join_conds ) {
 525                                 unset( $options[$forUpdateKey] );
 526                                 $options['FOR UPDATE'] = [];
 527
 528                                 $toCheck = $table;
 529                                 reset( $toCheck );
 530                                 while ( $toCheck ) {
 531                                         $alias = key( $toCheck );
 532                                         $name = $toCheck[$alias];
 533                                         unset( $toCheck[$alias] );
 534
 535                                         $hasAlias = !is_numeric( $alias );
 536                                         if ( !$hasAlias && is_string( $name ) ) {
 537                                                 $alias = $name;
 538                                         }
 539
 540                                         if ( !isset( $join_conds[$alias] ) ||
 541                                                 !preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_conds[$alias][0] )
 542                                         ) {
 543                                                 if ( is_array( $name ) ) {
 544                                                         // It's a parenthesized group, process all the tables inside the group.
 545                                                         $toCheck = array_merge( $toCheck, $name );
 546                                                 } else {
 547                                                         // Quote alias names so $this->tableName() won't mangle them
 548                                                         $options['FOR UPDATE'][] = $hasAlias ? $this->addIdentifierQuotes( $alias ) : $alias;
 549                                                 }
 550                                         }
 551                                 }
 552                         }
 553
 554                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 555                                 unset( $options['ORDER BY'] );
 556                         }
 557                 }
 558
 559                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 560         }
 561
 562         /**
 563          * INSERT wrapper, inserts an array into a table
 564          *
 565          * $args may be a single associative array, or an array of these with numeric keys,
 566          * for multi-row insert (Postgres version 8.2 and above only).
 567          *
 568          * @param string $table Name of the table to insert to.
 569          * @param array $args Items to insert into the table.
 570          * @param string $fname Name of the function, for profiling
 571          * @param array|string $options String or array. Valid options: IGNORE
 572          * @return bool Success of insert operation. IGNORE always returns true.
 573          */
 574         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 575                 if ( !count( $args ) ) {
 576                         return true;
 577                 }
 578
 579                 $table = $this->tableName( $table );
 580                 if ( !isset( $this->numericVersion ) ) {
 581                         $this->getServerVersion();
 582                 }
 583
 584                 if ( !is_array( $options ) ) {
 585                         $options = [ $options ];
 586                 }
 587
 588                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 589                         $multi = true;
 590                         $keys = array_keys( $args[0] );
 591                 } else {
 592                         $multi = false;
 593                         $keys = array_keys( $args );
 594                 }
 595
 596                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 597                 // @todo If PostgreSQL 9.5+, we could use ON CONFLICT DO NOTHING instead
 598                 $savepoint = $olde = null;
 599                 $numrowsinserted = 0;
 600                 if ( in_array( 'IGNORE', $options ) ) {
 601                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 602                         $olde = error_reporting( 0 );
 603                         // For future use, we may want to track the number of actual inserts
 604                         // Right now, insert (all writes) simply return true/false
 605                 }
 606
 607                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 608
 609                 if ( $multi ) {
 610                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 611                                 $first = true;
 612                                 foreach ( $args as $row ) {
 613                                         if ( $first ) {
 614                                                 $first = false;
 615                                         } else {
 616                                                 $sql .= ',';
 617                                         }
 618                                         $sql .= '(' . $this->makeList( $row ) . ')';
 619                                 }
 620                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 621                         } else {
 622                                 $res = true;
 623                                 $origsql = $sql;
 624                                 foreach ( $args as $row ) {
 625                                         $tempsql = $origsql;
 626                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 627
 628                                         if ( $savepoint ) {
 629                                                 $savepoint->savepoint();
 630                                         }
 631
 632                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 633
 634                                         if ( $savepoint ) {
 635                                                 $bar = pg_result_error( $this->lastResultHandle );
 636                                                 if ( $bar != false ) {
 637                                                         $savepoint->rollback();
 638                                                 } else {
 639                                                         $savepoint->release();
 640                                                         $numrowsinserted++;
 641                                                 }
 642                                         }
 643
 644                                         // If any of them fail, we fail overall for this function call
 645                                         // Note that this will be ignored if IGNORE is set
 646                                         if ( !$tempres ) {
 647                                                 $res = false;
 648                                         }
 649                                 }
 650                         }
 651                 } else {
 652                         // Not multi, just a lone insert
 653                         if ( $savepoint ) {
 654                                 $savepoint->savepoint();
 655                         }
 656
 657                         $sql .= '(' . $this->makeList( $args ) . ')';
 658                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 659                         if ( $savepoint ) {
 660                                 $bar = pg_result_error( $this->lastResultHandle );
 661                                 if ( $bar != false ) {
 662                                         $savepoint->rollback();
 663                                 } else {
 664                                         $savepoint->release();
 665                                         $numrowsinserted++;
 666                                 }
 667                         }
 668                 }
 669                 if ( $savepoint ) {
 670                         error_reporting( $olde );
 671                         $savepoint->commit();
 672
 673                         // Set the affected row count for the whole operation
 674                         $this->lastAffectedRowCount = $numrowsinserted;
 675
 676                         // IGNORE always returns true
 677                         return true;
 678                 }
 679
 680                 return $res;
 681         }
 682
 683         /**
 684          * INSERT SELECT wrapper
 685          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 686          * Source items may be literals rather then field names, but strings should
 687          * be quoted with Database::addQuotes()
 688          * $conds may be "*" to copy the whole table
 689          * srcTable may be an array of tables.
 690          * @todo FIXME: Implement this a little better (seperate select/insert)?
 691          *
 692          * @param string $destTable
 693          * @param array|string $srcTable
 694          * @param array $varMap
 695          * @param array $conds
 696          * @param string $fname
 697          * @param array $insertOptions
 698          * @param array $selectOptions
 699          * @param array $selectJoinConds
 700          * @return bool
 701          */
 702         public function nativeInsertSelect(
 703                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 704                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 705         ) {
 706                 if ( !is_array( $insertOptions ) ) {
 707                         $insertOptions = [ $insertOptions ];
 708                 }
 709
 710                 /*
 711                  * If IGNORE is set, use the non-native version.
 712                  * @todo If PostgreSQL 9.5+, we could use ON CONFLICT DO NOTHING
 713                  */
 714                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 715                         return $this->nonNativeInsertSelect(
 716                                 $destTable, $srcTable, $varMap, $conds, $fname, $insertOptions, $selectOptions, $selectJoinConds
 717                         );
 718                 }
 719
 720                 return parent::nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname,
 721                         $insertOptions, $selectOptions, $selectJoinConds );
 722         }
 723
 724         public function tableName( $name, $format = 'quoted' ) {
 725                 // Replace reserved words with better ones
 726                 $name = $this->remappedTableName( $name );
 727
 728                 return parent::tableName( $name, $format );
 729         }
 730
 731         /**
 732          * @param string $name
 733          * @return string Value of $name or remapped name if $name is a reserved keyword
 734          */
 735         public function remappedTableName( $name ) {
 736                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 737         }
 738
 739         /**
 740          * @param string $name
 741          * @param string $format
 742          * @return string Qualified and encoded (if requested) table name
 743          */
 744         public function realTableName( $name, $format = 'quoted' ) {
 745                 return parent::tableName( $name, $format );
 746         }
 747
 748         public function nextSequenceValue( $seqName ) {
 749                 return new NextSequenceValue;
 750         }
 751
 752         /**
 753          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 754          *
 755          * @param string $seqName
 756          * @return int
 757          */
 758         public function currentSequenceValue( $seqName ) {
 759                 $safeseq = str_replace( "'", "''", $seqName );
 760                 $res = $this->query( "SELECT currval('$safeseq')" );
 761                 $row = $this->fetchRow( $res );
 762                 $currval = $row[0];
 763
 764                 return $currval;
 765         }
 766
 767         public function textFieldSize( $table, $field ) {
 768                 $table = $this->tableName( $table );
 769                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 770                         FROM pg_class c, pg_attribute a, pg_type t
 771                         WHERE relname='$table' AND a.attrelid=c.oid AND
 772                                 a.atttypid=t.oid and a.attname='$field'";
 773                 $res = $this->query( $sql );
 774                 $row = $this->fetchObject( $res );
 775                 if ( $row->ftype == 'varchar' ) {
 776                         $size = $row->size - 4;
 777                 } else {
 778                         $size = $row->size;
 779                 }
 780
 781                 return $size;
 782         }
 783
 784         public function limitResult( $sql, $limit, $offset = false ) {
 785                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 786         }
 787
 788         public function wasDeadlock() {
 789                 // https://www.postgresql.org/docs/8.2/static/errcodes-appendix.html
 790                 return $this->lastErrno() === '40P01';
 791         }
 792
 793         public function wasLockTimeout() {
 794                 // https://www.postgresql.org/docs/8.2/static/errcodes-appendix.html
 795                 return $this->lastErrno() === '55P03';
 796         }
 797
 798         public function wasConnectionError( $errno ) {
 799                 // https://www.postgresql.org/docs/8.2/static/errcodes-appendix.html
 800                 static $codes = [ '08000', '08003', '08006', '08001', '08004', '57P01', '57P03', '53300' ];
 801
 802                 return in_array( $errno, $codes, true );
 803         }
 804
 805         protected function wasKnownStatementRollbackError() {
 806                 return false; // transaction has to be rolled-back from error state
 807         }
 808
 809         public function duplicateTableStructure(
 810                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 811         ) {
 812                 $newName = $this->addIdentifierQuotes( $newName );
 813                 $oldName = $this->addIdentifierQuotes( $oldName );
 814
 815                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 816                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 817         }
 818
 819         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 820                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 821                 $result = $this->query(
 822                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 823                 $endArray = [];
 824
 825                 foreach ( $result as $table ) {
 826                         $vars = get_object_vars( $table );
 827                         $table = array_pop( $vars );
 828                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 829                                 $endArray[] = $table;
 830                         }
 831                 }
 832
 833                 return $endArray;
 834         }
 835
 836         public function timestamp( $ts = 0 ) {
 837                 $ct = new ConvertibleTimestamp( $ts );
 838
 839                 return $ct->getTimestamp( TS_POSTGRES );
 840         }
 841
 842         /**
 843          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 844          * to https://secure.php.net/manual/en/ref.pgsql.php
 845          *
 846          * Parsing a postgres array can be a tricky problem, he's my
 847          * take on this, it handles multi-dimensional arrays plus
 848          * escaping using a nasty regexp to determine the limits of each
 849          * data-item.
 850          *
 851          * This should really be handled by PHP PostgreSQL module
 852          *
 853          * @since 1.19
 854          * @param string $text Postgreql array returned in a text form like {a,b}
 855          * @param string[] $output
 856          * @param int|bool $limit
 857          * @param int $offset
 858          * @return string[]
 859          */
 860         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 861                 if ( false === $limit ) {
 862                         $limit = strlen( $text ) - 1;
 863                         $output = [];
 864                 }
 865                 if ( '{}' == $text ) {
 866                         return $output;
 867                 }
 868                 do {
 869                         if ( '{' != $text[$offset] ) {
 870                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 871                                         $text, $match, 0, $offset );
 872                                 $offset += strlen( $match[0] );
 873                                 $output[] = ( '"' != $match[1][0]
 874                                         ? $match[1]
 875                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 876                                 if ( '},' == $match[3] ) {
 877                                         return $output;
 878                                 }
 879                         } else {
 880                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 881                         }
 882                 } while ( $limit > $offset );
 883
 884                 return $output;
 885         }
 886
 887         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 888                 return $valuedata;
 889         }
 890
 891         public function getSoftwareLink() {
 892                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 893         }
 894
 895         /**
 896          * Return current schema (executes SELECT current_schema())
 897          * Needs transaction
 898          *
 899          * @since 1.19
 900          * @return string Default schema for the current session
 901          */
 902         public function getCurrentSchema() {
 903                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 904                 $row = $this->fetchRow( $res );
 905
 906                 return $row[0];
 907         }
 908
 909         /**
 910          * Return list of schemas which are accessible without schema name
 911          * This is list does not contain magic keywords like "$user"
 912          * Needs transaction
 913          *
 914          * @see getSearchPath()
 915          * @see setSearchPath()
 916          * @since 1.19
 917          * @return array List of actual schemas for the current sesson
 918          */
 919         public function getSchemas() {
 920                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 921                 $row = $this->fetchRow( $res );
 922                 $schemas = [];
 923
 924                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 925
 926                 return $this->pg_array_parse( $row[0], $schemas );
 927         }
 928
 929         /**
 930          * Return search patch for schemas
 931          * This is different from getSchemas() since it contain magic keywords
 932          * (like "$user").
 933          * Needs transaction
 934          *
 935          * @since 1.19
 936          * @return array How to search for table names schemas for the current user
 937          */
 938         public function getSearchPath() {
 939                 $res = $this->query( "SHOW search_path", __METHOD__ );
 940                 $row = $this->fetchRow( $res );
 941
 942                 /* PostgreSQL returns SHOW values as strings */
 943
 944                 return explode( ",", $row[0] );
 945         }
 946
 947         /**
 948          * Update search_path, values should already be sanitized
 949          * Values may contain magic keywords like "$user"
 950          * @since 1.19
 951          *
 952          * @param array $search_path List of schemas to be searched by default
 953          */
 954         private function setSearchPath( $search_path ) {
 955                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 956         }
 957
 958         /**
 959          * Determine default schema for the current application
 960          * Adjust this session schema search path if desired schema exists
 961          * and is not alread there.
 962          *
 963          * We need to have name of the core schema stored to be able
 964          * to query database metadata.
 965          *
 966          * This will be also called by the installer after the schema is created
 967          *
 968          * @since 1.19
 969          *
 970          * @param string $desiredSchema
 971          */
 972         public function determineCoreSchema( $desiredSchema ) {
 973                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 974                 if ( $this->schemaExists( $desiredSchema ) ) {
 975                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 976                                 $this->coreSchema = $desiredSchema;
 977                                 $this->queryLogger->debug(
 978                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 979                         } else {
 980                                 /**
 981                                  * Prepend our schema (e.g. 'mediawiki') in front
 982                                  * of the search path
 983                                  * Fixes T17816
 984                                  */
 985                                 $search_path = $this->getSearchPath();
 986                                 array_unshift( $search_path,
 987                                         $this->addIdentifierQuotes( $desiredSchema ) );
 988                                 $this->setSearchPath( $search_path );
 989                                 $this->coreSchema = $desiredSchema;
 990                                 $this->queryLogger->debug(
 991                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 992                         }
 993                 } else {
 994                         $this->coreSchema = $this->getCurrentSchema();
 995                         $this->queryLogger->debug(
 996                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
 997                                 $this->coreSchema . "\"\n" );
 998                 }
 999                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1000                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1001         }
1002
1003         /**
1004          * Return schema name for core application tables
1005          *
1006          * @since 1.19
1007          * @return string Core schema name
1008          */
1009         public function getCoreSchema() {
1010                 return $this->coreSchema;
1011         }
1012
1013         public function getServerVersion() {
1014                 if ( !isset( $this->numericVersion ) ) {
1015                         $conn = $this->getBindingHandle();
1016                         $versionInfo = pg_version( $conn );
1017                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1018                                 // Old client, abort install
1019                                 $this->numericVersion = '7.3 or earlier';
1020                         } elseif ( isset( $versionInfo['server'] ) ) {
1021                                 // Normal client
1022                                 $this->numericVersion = $versionInfo['server'];
1023                         } else {
1024                                 // T18937: broken pgsql extension from PHP<5.3
1025                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1026                         }
1027                 }
1028
1029                 return $this->numericVersion;
1030         }
1031
1032         /**
1033          * Query whether a given relation exists (in the given schema, or the
1034          * default mw one if not given)
1035          * @param string $table
1036          * @param array|string $types
1037          * @param bool|string $schema
1038          * @return bool
1039          */
1040         private function relationExists( $table, $types, $schema = false ) {
1041                 if ( !is_array( $types ) ) {
1042                         $types = [ $types ];
1043                 }
1044                 if ( $schema === false ) {
1045                         $schema = $this->getCoreSchema();
1046                 }
1047                 $table = $this->realTableName( $table, 'raw' );
1048                 $etable = $this->addQuotes( $table );
1049                 $eschema = $this->addQuotes( $schema );
1050                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1051                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1052                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1053                 $res = $this->query( $sql );
1054                 $count = $res ? $res->numRows() : 0;
1055
1056                 return (bool)$count;
1057         }
1058
1059         /**
1060          * For backward compatibility, this function checks both tables and views.
1061          * @param string $table
1062          * @param string $fname
1063          * @param bool|string $schema
1064          * @return bool
1065          */
1066         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1067                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1068         }
1069
1070         public function sequenceExists( $sequence, $schema = false ) {
1071                 return $this->relationExists( $sequence, 'S', $schema );
1072         }
1073
1074         public function triggerExists( $table, $trigger ) {
1075                 $q = <<<SQL
1076         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1077                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1078                         AND tgrelid=pg_class.oid
1079                         AND nspname=%s AND relname=%s AND tgname=%s
1080 SQL;
1081                 $res = $this->query(
1082                         sprintf(
1083                                 $q,
1084                                 $this->addQuotes( $this->getCoreSchema() ),
1085                                 $this->addQuotes( $table ),
1086                                 $this->addQuotes( $trigger )
1087                         )
1088                 );
1089                 if ( !$res ) {
1090                         return null;
1091                 }
1092                 $rows = $res->numRows();
1093
1094                 return $rows;
1095         }
1096
1097         public function ruleExists( $table, $rule ) {
1098                 $exists = $this->selectField( 'pg_rules', 'rulename',
1099                         [
1100                                 'rulename' => $rule,
1101                                 'tablename' => $table,
1102                                 'schemaname' => $this->getCoreSchema()
1103                         ]
1104                 );
1105
1106                 return $exists === $rule;
1107         }
1108
1109         public function constraintExists( $table, $constraint ) {
1110                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1111                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1112                         $this->addQuotes( $this->getCoreSchema() ),
1113                         $this->addQuotes( $table ),
1114                         $this->addQuotes( $constraint )
1115                 );
1116                 $res = $this->query( $sql );
1117                 if ( !$res ) {
1118                         return null;
1119                 }
1120                 $rows = $res->numRows();
1121
1122                 return $rows;
1123         }
1124
1125         /**
1126          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1127          * @param string $schema
1128          * @return bool
1129          */
1130         public function schemaExists( $schema ) {
1131                 if ( !strlen( $schema ) ) {
1132                         return false; // short-circuit
1133                 }
1134
1135                 $exists = $this->selectField(
1136                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1137
1138                 return (bool)$exists;
1139         }
1140
1141         /**
1142          * Returns true if a given role (i.e. user) exists, false otherwise.
1143          * @param string $roleName
1144          * @return bool
1145          */
1146         public function roleExists( $roleName ) {
1147                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1148                         [ 'rolname' => $roleName ], __METHOD__ );
1149
1150                 return (bool)$exists;
1151         }
1152
1153         /**
1154          * @param string $table
1155          * @param string $field
1156          * @return PostgresField|null
1157          */
1158         public function fieldInfo( $table, $field ) {
1159                 return PostgresField::fromText( $this, $table, $field );
1160         }
1161
1162         /**
1163          * pg_field_type() wrapper
1164          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1165          * @param int $index Field number, starting from 0
1166          * @return string
1167          */
1168         public function fieldType( $res, $index ) {
1169                 if ( $res instanceof ResultWrapper ) {
1170                         $res = $res->result;
1171                 }
1172
1173                 return pg_field_type( $res, $index );
1174         }
1175
1176         public function encodeBlob( $b ) {
1177                 return new PostgresBlob( pg_escape_bytea( $b ) );
1178         }
1179
1180         public function decodeBlob( $b ) {
1181                 if ( $b instanceof PostgresBlob ) {
1182                         $b = $b->fetch();
1183                 } elseif ( $b instanceof Blob ) {
1184                         return $b->fetch();
1185                 }
1186
1187                 return pg_unescape_bytea( $b );
1188         }
1189
1190         public function strencode( $s ) {
1191                 // Should not be called by us
1192                 return pg_escape_string( $this->getBindingHandle(), (string)$s );
1193         }
1194
1195         public function addQuotes( $s ) {
1196                 $conn = $this->getBindingHandle();
1197
1198                 if ( is_null( $s ) ) {
1199                         return 'NULL';
1200                 } elseif ( is_bool( $s ) ) {
1201                         return intval( $s );
1202                 } elseif ( $s instanceof Blob ) {
1203                         if ( $s instanceof PostgresBlob ) {
1204                                 $s = $s->fetch();
1205                         } else {
1206                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1207                         }
1208                         return "'$s'";
1209                 } elseif ( $s instanceof NextSequenceValue ) {
1210                         return 'DEFAULT';
1211                 }
1212
1213                 return "'" . pg_escape_string( $conn, (string)$s ) . "'";
1214         }
1215
1216         /**
1217          * Postgres specific version of replaceVars.
1218          * Calls the parent version in Database.php
1219          *
1220          * @param string $ins SQL string, read from a stream (usually tables.sql)
1221          * @return string SQL string
1222          */
1223         protected function replaceVars( $ins ) {
1224                 $ins = parent::replaceVars( $ins );
1225
1226                 if ( $this->numericVersion >= 8.3 ) {
1227                         // Thanks for not providing backwards-compatibility, 8.3
1228                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1229                 }
1230
1231                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1232                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1233                 }
1234
1235                 return $ins;
1236         }
1237
1238         public function makeSelectOptions( $options ) {
1239                 $preLimitTail = $postLimitTail = '';
1240                 $startOpts = $useIndex = $ignoreIndex = '';
1241
1242                 $noKeyOptions = [];
1243                 foreach ( $options as $key => $option ) {
1244                         if ( is_numeric( $key ) ) {
1245                                 $noKeyOptions[$option] = true;
1246                         }
1247                 }
1248
1249                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1250
1251                 $preLimitTail .= $this->makeOrderBy( $options );
1252
1253                 if ( isset( $options['FOR UPDATE'] ) ) {
1254                         $postLimitTail .= ' FOR UPDATE OF ' .
1255                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1256                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1257                         $postLimitTail .= ' FOR UPDATE';
1258                 }
1259
1260                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1261                         $startOpts .= 'DISTINCT';
1262                 }
1263
1264                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1265         }
1266
1267         public function getDBname() {
1268                 return $this->dbName;
1269         }
1270
1271         public function getServer() {
1272                 return $this->server;
1273         }
1274
1275         public function buildConcat( $stringList ) {
1276                 return implode( ' || ', $stringList );
1277         }
1278
1279         public function buildGroupConcatField(
1280                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1281         ) {
1282                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1283
1284                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1285         }
1286
1287         public function buildStringCast( $field ) {
1288                 return $field . '::text';
1289         }
1290
1291         public function streamStatementEnd( &$sql, &$newLine ) {
1292                 # Allow dollar quoting for function declarations
1293                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1294                         if ( $this->delimiter ) {
1295                                 $this->delimiter = false;
1296                         } else {
1297                                 $this->delimiter = ';';
1298                         }
1299                 }
1300
1301                 return parent::streamStatementEnd( $sql, $newLine );
1302         }
1303
1304         public function doLockTables( array $read, array $write, $method ) {
1305                 $tablesWrite = [];
1306                 foreach ( $write as $table ) {
1307                         $tablesWrite[] = $this->tableName( $table );
1308                 }
1309                 $tablesRead = [];
1310                 foreach ( $read as $table ) {
1311                         $tablesRead[] = $this->tableName( $table );
1312                 }
1313
1314                 // Acquire locks for the duration of the current transaction...
1315                 if ( $tablesWrite ) {
1316                         $this->query(
1317                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1318                                 $method
1319                         );
1320                 }
1321                 if ( $tablesRead ) {
1322                         $this->query(
1323                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1324                                 $method
1325                         );
1326                 }
1327
1328                 return true;
1329         }
1330
1331         public function lockIsFree( $lockName, $method ) {
1332                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1333                         return false; // already held
1334                 }
1335                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1336                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1337                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1338                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1339                 $row = $this->fetchObject( $result );
1340
1341                 return ( $row->lockstatus === 't' );
1342         }
1343
1344         public function lock( $lockName, $method, $timeout = 5 ) {
1345                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1346                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1347                 $loop = new WaitConditionLoop(
1348                         function () use ( $lockName, $key, $timeout, $method ) {
1349                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1350                                 $row = $this->fetchObject( $res );
1351                                 if ( $row->lockstatus === 't' ) {
1352                                         parent::lock( $lockName, $method, $timeout ); // record
1353                                         return true;
1354                                 }
1355
1356                                 return WaitConditionLoop::CONDITION_CONTINUE;
1357                         },
1358                         $timeout
1359                 );
1360
1361                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1362         }
1363
1364         public function unlock( $lockName, $method ) {
1365                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1366                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1367                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1368                 $row = $this->fetchObject( $result );
1369
1370                 if ( $row->lockstatus === 't' ) {
1371                         parent::unlock( $lockName, $method ); // record
1372                         return true;
1373                 }
1374
1375                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1376
1377                 return false;
1378         }
1379
1380         public function serverIsReadOnly() {
1381                 $res = $this->query( "SHOW default_transaction_read_only", __METHOD__ );
1382                 $row = $this->fetchObject( $res );
1383
1384                 return $row ? ( strtolower( $row->default_transaction_read_only ) === 'on' ) : false;
1385         }
1386
1387         /**
1388          * @param string $lockName
1389          * @return string Integer
1390          */
1391         private function bigintFromLockName( $lockName ) {
1392                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1393         }
1394 }
1395
1396 class_alias( DatabasePostgres::class, 'DatabasePostgres' );