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                         // pg_connect() user $user as the default database. Since a database is *required*,
 109                         // at least pick a "don't care" database that is more likely to exist. This case
 110                         // arrises when LoadBalancer::getConnection( $i, [], '' ) is used.
 111                         'dbname' => strlen( $dbName ) ? $dbName : 'postgres',
 112                         'user' => $user,
 113                         'password' => $password
 114                 ];
 115                 if ( $server != false && $server != '' ) {
 116                         $connectVars['host'] = $server;
 117                 }
 118                 if ( (int)$this->port > 0 ) {
 119                         $connectVars['port'] = (int)$this->port;
 120                 }
 121                 if ( $this->mFlags & self::DBO_SSL ) {
 122                         $connectVars['sslmode'] = 1;
 123                 }
 124
 125                 $this->connectString = $this->makeConnectionString( $connectVars );
 126                 $this->close();
 127                 $this->installErrorHandler();
 128
 129                 try {
 130                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 131                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 132                 } catch ( Exception $ex ) {
 133                         $this->restoreErrorHandler();
 134                         throw $ex;
 135                 }
 136
 137                 $phpError = $this->restoreErrorHandler();
 138
 139                 if ( !$this->mConn ) {
 140                         $this->queryLogger->debug(
 141                                 "DB connection error\n" .
 142                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 143                                 substr( $password, 0, 3 ) . "...\n"
 144                         );
 145                         $this->queryLogger->debug( $this->lastError() . "\n" );
 146                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 147                 }
 148
 149                 $this->mOpened = true;
 150
 151                 # If called from the command-line (e.g. importDump), only show errors
 152                 if ( $this->cliMode ) {
 153                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 154                 }
 155
 156                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 157                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 158                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 159                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 160                 if ( $this->getServerVersion() >= 9.0 ) {
 161                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 162                 }
 163
 164                 $this->determineCoreSchema( $this->mSchema );
 165                 // The schema to be used is now in the search path; no need for explicit qualification
 166                 $this->mSchema = '';
 167
 168                 return $this->mConn;
 169         }
 170
 171         public function databasesAreIndependent() {
 172                 return true;
 173         }
 174
 175         /**
 176          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 177          * DB name doesn't match the open connection, open a new one
 178          * @param string $db
 179          * @return bool
 180          * @throws DBUnexpectedError
 181          */
 182         public function selectDB( $db ) {
 183                 if ( $this->mDBname !== $db ) {
 184                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 185                 } else {
 186                         return true;
 187                 }
 188         }
 189
 190         /**
 191          * @param string[] $vars
 192          * @return string
 193          */
 194         private function makeConnectionString( $vars ) {
 195                 $s = '';
 196                 foreach ( $vars as $name => $value ) {
 197                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 198                 }
 199
 200                 return $s;
 201         }
 202
 203         protected function closeConnection() {
 204                 return $this->mConn ? pg_close( $this->mConn ) : true;
 205         }
 206
 207         public function doQuery( $sql ) {
 208                 $conn = $this->getBindingHandle();
 209
 210                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 211                 // Clear previously left over PQresult
 212                 while ( $res = pg_get_result( $conn ) ) {
 213                         pg_free_result( $res );
 214                 }
 215                 if ( pg_send_query( $conn, $sql ) === false ) {
 216                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 217                 }
 218                 $this->mLastResult = pg_get_result( $conn );
 219                 $this->mAffectedRows = null;
 220                 if ( pg_result_error( $this->mLastResult ) ) {
 221                         return false;
 222                 }
 223
 224                 return $this->mLastResult;
 225         }
 226
 227         protected function dumpError() {
 228                 $diags = [
 229                         PGSQL_DIAG_SEVERITY,
 230                         PGSQL_DIAG_SQLSTATE,
 231                         PGSQL_DIAG_MESSAGE_PRIMARY,
 232                         PGSQL_DIAG_MESSAGE_DETAIL,
 233                         PGSQL_DIAG_MESSAGE_HINT,
 234                         PGSQL_DIAG_STATEMENT_POSITION,
 235                         PGSQL_DIAG_INTERNAL_POSITION,
 236                         PGSQL_DIAG_INTERNAL_QUERY,
 237                         PGSQL_DIAG_CONTEXT,
 238                         PGSQL_DIAG_SOURCE_FILE,
 239                         PGSQL_DIAG_SOURCE_LINE,
 240                         PGSQL_DIAG_SOURCE_FUNCTION
 241                 ];
 242                 foreach ( $diags as $d ) {
 243                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 244                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 245                 }
 246         }
 247
 248         public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 249                 if ( $tempIgnore ) {
 250                         /* Check for constraint violation */
 251                         if ( $errno === '23505' ) {
 252                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 253
 254                                 return;
 255                         }
 256                 }
 257                 /* Transaction stays in the ERROR state until rolled back */
 258                 if ( $this->mTrxLevel ) {
 259                         // Throw away the transaction state, then raise the error as normal.
 260                         // Note that if this connection is managed by LBFactory, it's already expected
 261                         // that the other transactions LBFactory manages will be rolled back.
 262                         $this->rollback( __METHOD__, self::FLUSHING_INTERNAL );
 263                 }
 264                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 265         }
 266
 267         public function freeResult( $res ) {
 268                 if ( $res instanceof ResultWrapper ) {
 269                         $res = $res->result;
 270                 }
 271                 MediaWiki\suppressWarnings();
 272                 $ok = pg_free_result( $res );
 273                 MediaWiki\restoreWarnings();
 274                 if ( !$ok ) {
 275                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 276                 }
 277         }
 278
 279         public function fetchObject( $res ) {
 280                 if ( $res instanceof ResultWrapper ) {
 281                         $res = $res->result;
 282                 }
 283                 MediaWiki\suppressWarnings();
 284                 $row = pg_fetch_object( $res );
 285                 MediaWiki\restoreWarnings();
 286                 # @todo FIXME: HACK HACK HACK HACK debug
 287
 288                 # @todo hashar: not sure if the following test really trigger if the object
 289                 #          fetching failed.
 290                 $conn = $this->getBindingHandle();
 291                 if ( pg_last_error( $conn ) ) {
 292                         throw new DBUnexpectedError(
 293                                 $this,
 294                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 295                         );
 296                 }
 297
 298                 return $row;
 299         }
 300
 301         public function fetchRow( $res ) {
 302                 if ( $res instanceof ResultWrapper ) {
 303                         $res = $res->result;
 304                 }
 305                 MediaWiki\suppressWarnings();
 306                 $row = pg_fetch_array( $res );
 307                 MediaWiki\restoreWarnings();
 308
 309                 $conn = $this->getBindingHandle();
 310                 if ( pg_last_error( $conn ) ) {
 311                         throw new DBUnexpectedError(
 312                                 $this,
 313                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 314                         );
 315                 }
 316
 317                 return $row;
 318         }
 319
 320         public function numRows( $res ) {
 321                 if ( $res instanceof ResultWrapper ) {
 322                         $res = $res->result;
 323                 }
 324                 MediaWiki\suppressWarnings();
 325                 $n = pg_num_rows( $res );
 326                 MediaWiki\restoreWarnings();
 327
 328                 $conn = $this->getBindingHandle();
 329                 if ( pg_last_error( $conn ) ) {
 330                         throw new DBUnexpectedError(
 331                                 $this,
 332                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 333                         );
 334                 }
 335
 336                 return $n;
 337         }
 338
 339         public function numFields( $res ) {
 340                 if ( $res instanceof ResultWrapper ) {
 341                         $res = $res->result;
 342                 }
 343
 344                 return pg_num_fields( $res );
 345         }
 346
 347         public function fieldName( $res, $n ) {
 348                 if ( $res instanceof ResultWrapper ) {
 349                         $res = $res->result;
 350                 }
 351
 352                 return pg_field_name( $res, $n );
 353         }
 354
 355         /**
 356          * Return the result of the last call to nextSequenceValue();
 357          * This must be called after nextSequenceValue().
 358          *
 359          * @return int|null
 360          */
 361         public function insertId() {
 362                 return $this->mInsertId;
 363         }
 364
 365         public function dataSeek( $res, $row ) {
 366                 if ( $res instanceof ResultWrapper ) {
 367                         $res = $res->result;
 368                 }
 369
 370                 return pg_result_seek( $res, $row );
 371         }
 372
 373         public function lastError() {
 374                 if ( $this->mConn ) {
 375                         if ( $this->mLastResult ) {
 376                                 return pg_result_error( $this->mLastResult );
 377                         } else {
 378                                 return pg_last_error();
 379                         }
 380                 }
 381
 382                 return $this->getLastPHPError() ?: 'No database connection';
 383         }
 384
 385         public function lastErrno() {
 386                 if ( $this->mLastResult ) {
 387                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 388                 } else {
 389                         return false;
 390                 }
 391         }
 392
 393         public function affectedRows() {
 394                 if ( !is_null( $this->mAffectedRows ) ) {
 395                         // Forced result for simulated queries
 396                         return $this->mAffectedRows;
 397                 }
 398                 if ( empty( $this->mLastResult ) ) {
 399                         return 0;
 400                 }
 401
 402                 return pg_affected_rows( $this->mLastResult );
 403         }
 404
 405         /**
 406          * Estimate rows in dataset
 407          * Returns estimated count, based on EXPLAIN output
 408          * This is not necessarily an accurate estimate, so use sparingly
 409          * Returns -1 if count cannot be found
 410          * Takes same arguments as Database::select()
 411          *
 412          * @param string $table
 413          * @param string $vars
 414          * @param string $conds
 415          * @param string $fname
 416          * @param array $options
 417          * @return int
 418          */
 419         public function estimateRowCount( $table, $vars = '*', $conds = '',
 420                 $fname = __METHOD__, $options = []
 421         ) {
 422                 $options['EXPLAIN'] = true;
 423                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 424                 $rows = -1;
 425                 if ( $res ) {
 426                         $row = $this->fetchRow( $res );
 427                         $count = [];
 428                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 429                                 $rows = (int)$count[1];
 430                         }
 431                 }
 432
 433                 return $rows;
 434         }
 435
 436         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 437                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 438                 $res = $this->query( $sql, $fname );
 439                 if ( !$res ) {
 440                         return null;
 441                 }
 442                 foreach ( $res as $row ) {
 443                         if ( $row->indexname == $this->indexName( $index ) ) {
 444                                 return $row;
 445                         }
 446                 }
 447
 448                 return false;
 449         }
 450
 451         public function indexAttributes( $index, $schema = false ) {
 452                 if ( $schema === false ) {
 453                         $schema = $this->getCoreSchema();
 454                 }
 455                 /*
 456                  * A subquery would be not needed if we didn't care about the order
 457                  * of attributes, but we do
 458                  */
 459                 $sql = <<<__INDEXATTR__
 460
 461                         SELECT opcname,
 462                                 attname,
 463                                 i.indoption[s.g] as option,
 464                                 pg_am.amname
 465                         FROM
 466                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 467                                         FROM
 468                                                 pg_index isub
 469                                         JOIN pg_class cis
 470                                                 ON cis.oid=isub.indexrelid
 471                                         JOIN pg_namespace ns
 472                                                 ON cis.relnamespace = ns.oid
 473                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 474                                 pg_attribute,
 475                                 pg_opclass opcls,
 476                                 pg_am,
 477                                 pg_class ci
 478                                 JOIN pg_index i
 479                                         ON ci.oid=i.indexrelid
 480                                 JOIN pg_class ct
 481                                         ON ct.oid = i.indrelid
 482                                 JOIN pg_namespace n
 483                                         ON ci.relnamespace = n.oid
 484                                 WHERE
 485                                         ci.relname='$index' AND n.nspname='$schema'
 486                                         AND     attrelid = ct.oid
 487                                         AND     i.indkey[s.g] = attnum
 488                                         AND     i.indclass[s.g] = opcls.oid
 489                                         AND     pg_am.oid = opcls.opcmethod
 490 __INDEXATTR__;
 491                 $res = $this->query( $sql, __METHOD__ );
 492                 $a = [];
 493                 if ( $res ) {
 494                         foreach ( $res as $row ) {
 495                                 $a[] = [
 496                                         $row->attname,
 497                                         $row->opcname,
 498                                         $row->amname,
 499                                         $row->option ];
 500                         }
 501                 } else {
 502                         return null;
 503                 }
 504
 505                 return $a;
 506         }
 507
 508         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 509                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 510                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 511                         $this->strencode( $this->indexName( $index ) ) .
 512                         ")'";
 513                 $res = $this->query( $sql, $fname );
 514                 if ( !$res ) {
 515                         return null;
 516                 }
 517
 518                 return $res->numRows() > 0;
 519         }
 520
 521         public function selectSQLText(
 522                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 523         ) {
 524                 if ( is_string( $options ) ) {
 525                         $options = [ $options ];
 526                 }
 527
 528                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 529                 // to the parent function to get the actual SQL text.
 530                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 531                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 532                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 533                 // accordingly.
 534                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 535                 if ( is_array( $options ) ) {
 536                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 537                         if ( $forUpdateKey !== false && $join_conds ) {
 538                                 unset( $options[$forUpdateKey] );
 539                                 $options['FOR UPDATE'] = [];
 540
 541                                 // All tables not in $join_conds are good
 542                                 foreach ( $table as $alias => $name ) {
 543                                         if ( is_numeric( $alias ) ) {
 544                                                 $alias = $name;
 545                                         }
 546                                         if ( !isset( $join_conds[$alias] ) ) {
 547                                                 $options['FOR UPDATE'][] = $alias;
 548                                         }
 549                                 }
 550
 551                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 552                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 553                                                 $options['FOR UPDATE'][] = $table_cond;
 554                                         }
 555                                 }
 556
 557                                 // Quote alias names so $this->tableName() won't mangle them
 558                                 $options['FOR UPDATE'] = array_map( function ( $name ) use ( $table ) {
 559                                         return isset( $table[$name] ) ? $this->addIdentifierQuotes( $name ) : $name;
 560                                 }, $options['FOR UPDATE'] );
 561                         }
 562
 563                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 564                                 unset( $options['ORDER BY'] );
 565                         }
 566                 }
 567
 568                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 569         }
 570
 571         /**
 572          * INSERT wrapper, inserts an array into a table
 573          *
 574          * $args may be a single associative array, or an array of these with numeric keys,
 575          * for multi-row insert (Postgres version 8.2 and above only).
 576          *
 577          * @param string $table Name of the table to insert to.
 578          * @param array $args Items to insert into the table.
 579          * @param string $fname Name of the function, for profiling
 580          * @param array|string $options String or array. Valid options: IGNORE
 581          * @return bool Success of insert operation. IGNORE always returns true.
 582          */
 583         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 584                 if ( !count( $args ) ) {
 585                         return true;
 586                 }
 587
 588                 $table = $this->tableName( $table );
 589                 if ( !isset( $this->numericVersion ) ) {
 590                         $this->getServerVersion();
 591                 }
 592
 593                 if ( !is_array( $options ) ) {
 594                         $options = [ $options ];
 595                 }
 596
 597                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 598                         $multi = true;
 599                         $keys = array_keys( $args[0] );
 600                 } else {
 601                         $multi = false;
 602                         $keys = array_keys( $args );
 603                 }
 604
 605                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 606                 $savepoint = $olde = null;
 607                 $numrowsinserted = 0;
 608                 if ( in_array( 'IGNORE', $options ) ) {
 609                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 610                         $olde = error_reporting( 0 );
 611                         // For future use, we may want to track the number of actual inserts
 612                         // Right now, insert (all writes) simply return true/false
 613                 }
 614
 615                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 616
 617                 if ( $multi ) {
 618                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 619                                 $first = true;
 620                                 foreach ( $args as $row ) {
 621                                         if ( $first ) {
 622                                                 $first = false;
 623                                         } else {
 624                                                 $sql .= ',';
 625                                         }
 626                                         $sql .= '(' . $this->makeList( $row ) . ')';
 627                                 }
 628                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 629                         } else {
 630                                 $res = true;
 631                                 $origsql = $sql;
 632                                 foreach ( $args as $row ) {
 633                                         $tempsql = $origsql;
 634                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 635
 636                                         if ( $savepoint ) {
 637                                                 $savepoint->savepoint();
 638                                         }
 639
 640                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 641
 642                                         if ( $savepoint ) {
 643                                                 $bar = pg_result_error( $this->mLastResult );
 644                                                 if ( $bar != false ) {
 645                                                         $savepoint->rollback();
 646                                                 } else {
 647                                                         $savepoint->release();
 648                                                         $numrowsinserted++;
 649                                                 }
 650                                         }
 651
 652                                         // If any of them fail, we fail overall for this function call
 653                                         // Note that this will be ignored if IGNORE is set
 654                                         if ( !$tempres ) {
 655                                                 $res = false;
 656                                         }
 657                                 }
 658                         }
 659                 } else {
 660                         // Not multi, just a lone insert
 661                         if ( $savepoint ) {
 662                                 $savepoint->savepoint();
 663                         }
 664
 665                         $sql .= '(' . $this->makeList( $args ) . ')';
 666                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 667                         if ( $savepoint ) {
 668                                 $bar = pg_result_error( $this->mLastResult );
 669                                 if ( $bar != false ) {
 670                                         $savepoint->rollback();
 671                                 } else {
 672                                         $savepoint->release();
 673                                         $numrowsinserted++;
 674                                 }
 675                         }
 676                 }
 677                 if ( $savepoint ) {
 678                         error_reporting( $olde );
 679                         $savepoint->commit();
 680
 681                         // Set the affected row count for the whole operation
 682                         $this->mAffectedRows = $numrowsinserted;
 683
 684                         // IGNORE always returns true
 685                         return true;
 686                 }
 687
 688                 return $res;
 689         }
 690
 691         /**
 692          * INSERT SELECT wrapper
 693          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 694          * Source items may be literals rather then field names, but strings should
 695          * be quoted with Database::addQuotes()
 696          * $conds may be "*" to copy the whole table
 697          * srcTable may be an array of tables.
 698          * @todo FIXME: Implement this a little better (seperate select/insert)?
 699          *
 700          * @param string $destTable
 701          * @param array|string $srcTable
 702          * @param array $varMap
 703          * @param array $conds
 704          * @param string $fname
 705          * @param array $insertOptions
 706          * @param array $selectOptions
 707          * @param array $selectJoinConds
 708          * @return bool
 709          */
 710         public function nativeInsertSelect(
 711                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 712                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 713         ) {
 714                 if ( !is_array( $insertOptions ) ) {
 715                         $insertOptions = [ $insertOptions ];
 716                 }
 717
 718                 /*
 719                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 720                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 721                  */
 722                 $savepoint = $olde = null;
 723                 $numrowsinserted = 0;
 724                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 725                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 726                         $olde = error_reporting( 0 );
 727                         $savepoint->savepoint();
 728                 }
 729
 730                 $res = parent::nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname,
 731                         $insertOptions, $selectOptions, $selectJoinConds );
 732
 733                 if ( $savepoint ) {
 734                         $bar = pg_result_error( $this->mLastResult );
 735                         if ( $bar != false ) {
 736                                 $savepoint->rollback();
 737                         } else {
 738                                 $savepoint->release();
 739                                 $numrowsinserted++;
 740                         }
 741                         error_reporting( $olde );
 742                         $savepoint->commit();
 743
 744                         // Set the affected row count for the whole operation
 745                         $this->mAffectedRows = $numrowsinserted;
 746
 747                         // IGNORE always returns true
 748                         return true;
 749                 }
 750
 751                 return $res;
 752         }
 753
 754         public function tableName( $name, $format = 'quoted' ) {
 755                 // Replace reserved words with better ones
 756                 $name = $this->remappedTableName( $name );
 757
 758                 return parent::tableName( $name, $format );
 759         }
 760
 761         /**
 762          * @param string $name
 763          * @return string Value of $name or remapped name if $name is a reserved keyword
 764          */
 765         public function remappedTableName( $name ) {
 766                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 767         }
 768
 769         /**
 770          * @param string $name
 771          * @param string $format
 772          * @return string Qualified and encoded (if requested) table name
 773          */
 774         public function realTableName( $name, $format = 'quoted' ) {
 775                 return parent::tableName( $name, $format );
 776         }
 777
 778         public function nextSequenceValue( $seqName ) {
 779                 $safeseq = str_replace( "'", "''", $seqName );
 780                 $res = $this->query( "SELECT nextval('$safeseq')" );
 781                 $row = $this->fetchRow( $res );
 782                 $this->mInsertId = is_null( $row[0] ) ? null : (int)$row[0];
 783
 784                 return $this->mInsertId;
 785         }
 786
 787         /**
 788          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 789          *
 790          * @param string $seqName
 791          * @return int
 792          */
 793         public function currentSequenceValue( $seqName ) {
 794                 $safeseq = str_replace( "'", "''", $seqName );
 795                 $res = $this->query( "SELECT currval('$safeseq')" );
 796                 $row = $this->fetchRow( $res );
 797                 $currval = $row[0];
 798
 799                 return $currval;
 800         }
 801
 802         public function textFieldSize( $table, $field ) {
 803                 $table = $this->tableName( $table );
 804                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 805                         FROM pg_class c, pg_attribute a, pg_type t
 806                         WHERE relname='$table' AND a.attrelid=c.oid AND
 807                                 a.atttypid=t.oid and a.attname='$field'";
 808                 $res = $this->query( $sql );
 809                 $row = $this->fetchObject( $res );
 810                 if ( $row->ftype == 'varchar' ) {
 811                         $size = $row->size - 4;
 812                 } else {
 813                         $size = $row->size;
 814                 }
 815
 816                 return $size;
 817         }
 818
 819         public function limitResult( $sql, $limit, $offset = false ) {
 820                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 821         }
 822
 823         public function wasDeadlock() {
 824                 return $this->lastErrno() == '40P01';
 825         }
 826
 827         public function duplicateTableStructure(
 828                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 829         ) {
 830                 $newName = $this->addIdentifierQuotes( $newName );
 831                 $oldName = $this->addIdentifierQuotes( $oldName );
 832
 833                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 834                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 835         }
 836
 837         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 838                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 839                 $result = $this->query(
 840                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 841                 $endArray = [];
 842
 843                 foreach ( $result as $table ) {
 844                         $vars = get_object_vars( $table );
 845                         $table = array_pop( $vars );
 846                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 847                                 $endArray[] = $table;
 848                         }
 849                 }
 850
 851                 return $endArray;
 852         }
 853
 854         public function timestamp( $ts = 0 ) {
 855                 $ct = new ConvertibleTimestamp( $ts );
 856
 857                 return $ct->getTimestamp( TS_POSTGRES );
 858         }
 859
 860         /**
 861          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 862          * to https://secure.php.net/manual/en/ref.pgsql.php
 863          *
 864          * Parsing a postgres array can be a tricky problem, he's my
 865          * take on this, it handles multi-dimensional arrays plus
 866          * escaping using a nasty regexp to determine the limits of each
 867          * data-item.
 868          *
 869          * This should really be handled by PHP PostgreSQL module
 870          *
 871          * @since 1.19
 872          * @param string $text Postgreql array returned in a text form like {a,b}
 873          * @param string[] $output
 874          * @param int|bool $limit
 875          * @param int $offset
 876          * @return string[]
 877          */
 878         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 879                 if ( false === $limit ) {
 880                         $limit = strlen( $text ) - 1;
 881                         $output = [];
 882                 }
 883                 if ( '{}' == $text ) {
 884                         return $output;
 885                 }
 886                 do {
 887                         if ( '{' != $text[$offset] ) {
 888                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 889                                         $text, $match, 0, $offset );
 890                                 $offset += strlen( $match[0] );
 891                                 $output[] = ( '"' != $match[1][0]
 892                                         ? $match[1]
 893                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 894                                 if ( '},' == $match[3] ) {
 895                                         return $output;
 896                                 }
 897                         } else {
 898                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 899                         }
 900                 } while ( $limit > $offset );
 901
 902                 return $output;
 903         }
 904
 905         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 906                 return $valuedata;
 907         }
 908
 909         public function getSoftwareLink() {
 910                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 911         }
 912
 913         /**
 914          * Return current schema (executes SELECT current_schema())
 915          * Needs transaction
 916          *
 917          * @since 1.19
 918          * @return string Default schema for the current session
 919          */
 920         public function getCurrentSchema() {
 921                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 922                 $row = $this->fetchRow( $res );
 923
 924                 return $row[0];
 925         }
 926
 927         /**
 928          * Return list of schemas which are accessible without schema name
 929          * This is list does not contain magic keywords like "$user"
 930          * Needs transaction
 931          *
 932          * @see getSearchPath()
 933          * @see setSearchPath()
 934          * @since 1.19
 935          * @return array List of actual schemas for the current sesson
 936          */
 937         public function getSchemas() {
 938                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 939                 $row = $this->fetchRow( $res );
 940                 $schemas = [];
 941
 942                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 943
 944                 return $this->pg_array_parse( $row[0], $schemas );
 945         }
 946
 947         /**
 948          * Return search patch for schemas
 949          * This is different from getSchemas() since it contain magic keywords
 950          * (like "$user").
 951          * Needs transaction
 952          *
 953          * @since 1.19
 954          * @return array How to search for table names schemas for the current user
 955          */
 956         public function getSearchPath() {
 957                 $res = $this->query( "SHOW search_path", __METHOD__ );
 958                 $row = $this->fetchRow( $res );
 959
 960                 /* PostgreSQL returns SHOW values as strings */
 961
 962                 return explode( ",", $row[0] );
 963         }
 964
 965         /**
 966          * Update search_path, values should already be sanitized
 967          * Values may contain magic keywords like "$user"
 968          * @since 1.19
 969          *
 970          * @param array $search_path List of schemas to be searched by default
 971          */
 972         private function setSearchPath( $search_path ) {
 973                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 974         }
 975
 976         /**
 977          * Determine default schema for the current application
 978          * Adjust this session schema search path if desired schema exists
 979          * and is not alread there.
 980          *
 981          * We need to have name of the core schema stored to be able
 982          * to query database metadata.
 983          *
 984          * This will be also called by the installer after the schema is created
 985          *
 986          * @since 1.19
 987          *
 988          * @param string $desiredSchema
 989          */
 990         public function determineCoreSchema( $desiredSchema ) {
 991                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 992                 if ( $this->schemaExists( $desiredSchema ) ) {
 993                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 994                                 $this->mCoreSchema = $desiredSchema;
 995                                 $this->queryLogger->debug(
 996                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 997                         } else {
 998                                 /**
 999                                  * Prepend our schema (e.g. 'mediawiki') in front
1000                                  * of the search path
1001                                  * Fixes T17816
1002                                  */
1003                                 $search_path = $this->getSearchPath();
1004                                 array_unshift( $search_path,
1005                                         $this->addIdentifierQuotes( $desiredSchema ) );
1006                                 $this->setSearchPath( $search_path );
1007                                 $this->mCoreSchema = $desiredSchema;
1008                                 $this->queryLogger->debug(
1009                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1010                         }
1011                 } else {
1012                         $this->mCoreSchema = $this->getCurrentSchema();
1013                         $this->queryLogger->debug(
1014                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1015                                 $this->mCoreSchema . "\"\n" );
1016                 }
1017                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1018                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1019         }
1020
1021         /**
1022          * Return schema name for core application tables
1023          *
1024          * @since 1.19
1025          * @return string Core schema name
1026          */
1027         public function getCoreSchema() {
1028                 return $this->mCoreSchema;
1029         }
1030
1031         public function getServerVersion() {
1032                 if ( !isset( $this->numericVersion ) ) {
1033                         $conn = $this->getBindingHandle();
1034                         $versionInfo = pg_version( $conn );
1035                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1036                                 // Old client, abort install
1037                                 $this->numericVersion = '7.3 or earlier';
1038                         } elseif ( isset( $versionInfo['server'] ) ) {
1039                                 // Normal client
1040                                 $this->numericVersion = $versionInfo['server'];
1041                         } else {
1042                                 // T18937: broken pgsql extension from PHP<5.3
1043                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1044                         }
1045                 }
1046
1047                 return $this->numericVersion;
1048         }
1049
1050         /**
1051          * Query whether a given relation exists (in the given schema, or the
1052          * default mw one if not given)
1053          * @param string $table
1054          * @param array|string $types
1055          * @param bool|string $schema
1056          * @return bool
1057          */
1058         private function relationExists( $table, $types, $schema = false ) {
1059                 if ( !is_array( $types ) ) {
1060                         $types = [ $types ];
1061                 }
1062                 if ( $schema === false ) {
1063                         $schema = $this->getCoreSchema();
1064                 }
1065                 $table = $this->realTableName( $table, 'raw' );
1066                 $etable = $this->addQuotes( $table );
1067                 $eschema = $this->addQuotes( $schema );
1068                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1069                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1070                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1071                 $res = $this->query( $sql );
1072                 $count = $res ? $res->numRows() : 0;
1073
1074                 return (bool)$count;
1075         }
1076
1077         /**
1078          * For backward compatibility, this function checks both tables and views.
1079          * @param string $table
1080          * @param string $fname
1081          * @param bool|string $schema
1082          * @return bool
1083          */
1084         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1085                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1086         }
1087
1088         public function sequenceExists( $sequence, $schema = false ) {
1089                 return $this->relationExists( $sequence, 'S', $schema );
1090         }
1091
1092         public function triggerExists( $table, $trigger ) {
1093                 $q = <<<SQL
1094         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1095                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1096                         AND tgrelid=pg_class.oid
1097                         AND nspname=%s AND relname=%s AND tgname=%s
1098 SQL;
1099                 $res = $this->query(
1100                         sprintf(
1101                                 $q,
1102                                 $this->addQuotes( $this->getCoreSchema() ),
1103                                 $this->addQuotes( $table ),
1104                                 $this->addQuotes( $trigger )
1105                         )
1106                 );
1107                 if ( !$res ) {
1108                         return null;
1109                 }
1110                 $rows = $res->numRows();
1111
1112                 return $rows;
1113         }
1114
1115         public function ruleExists( $table, $rule ) {
1116                 $exists = $this->selectField( 'pg_rules', 'rulename',
1117                         [
1118                                 'rulename' => $rule,
1119                                 'tablename' => $table,
1120                                 'schemaname' => $this->getCoreSchema()
1121                         ]
1122                 );
1123
1124                 return $exists === $rule;
1125         }
1126
1127         public function constraintExists( $table, $constraint ) {
1128                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1129                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1130                         $this->addQuotes( $this->getCoreSchema() ),
1131                         $this->addQuotes( $table ),
1132                         $this->addQuotes( $constraint )
1133                 );
1134                 $res = $this->query( $sql );
1135                 if ( !$res ) {
1136                         return null;
1137                 }
1138                 $rows = $res->numRows();
1139
1140                 return $rows;
1141         }
1142
1143         /**
1144          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1145          * @param string $schema
1146          * @return bool
1147          */
1148         public function schemaExists( $schema ) {
1149                 if ( !strlen( $schema ) ) {
1150                         return false; // short-circuit
1151                 }
1152
1153                 $exists = $this->selectField(
1154                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1155
1156                 return (bool)$exists;
1157         }
1158
1159         /**
1160          * Returns true if a given role (i.e. user) exists, false otherwise.
1161          * @param string $roleName
1162          * @return bool
1163          */
1164         public function roleExists( $roleName ) {
1165                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1166                         [ 'rolname' => $roleName ], __METHOD__ );
1167
1168                 return (bool)$exists;
1169         }
1170
1171         /**
1172          * @var string $table
1173          * @var string $field
1174          * @return PostgresField|null
1175          */
1176         public function fieldInfo( $table, $field ) {
1177                 return PostgresField::fromText( $this, $table, $field );
1178         }
1179
1180         /**
1181          * pg_field_type() wrapper
1182          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1183          * @param int $index Field number, starting from 0
1184          * @return string
1185          */
1186         public function fieldType( $res, $index ) {
1187                 if ( $res instanceof ResultWrapper ) {
1188                         $res = $res->result;
1189                 }
1190
1191                 return pg_field_type( $res, $index );
1192         }
1193
1194         public function encodeBlob( $b ) {
1195                 return new PostgresBlob( pg_escape_bytea( $b ) );
1196         }
1197
1198         public function decodeBlob( $b ) {
1199                 if ( $b instanceof PostgresBlob ) {
1200                         $b = $b->fetch();
1201                 } elseif ( $b instanceof Blob ) {
1202                         return $b->fetch();
1203                 }
1204
1205                 return pg_unescape_bytea( $b );
1206         }
1207
1208         public function strencode( $s ) {
1209                 // Should not be called by us
1210                 return pg_escape_string( $this->getBindingHandle(), $s );
1211         }
1212
1213         public function addQuotes( $s ) {
1214                 $conn = $this->getBindingHandle();
1215
1216                 if ( is_null( $s ) ) {
1217                         return 'NULL';
1218                 } elseif ( is_bool( $s ) ) {
1219                         return intval( $s );
1220                 } elseif ( $s instanceof Blob ) {
1221                         if ( $s instanceof PostgresBlob ) {
1222                                 $s = $s->fetch();
1223                         } else {
1224                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1225                         }
1226                         return "'$s'";
1227                 }
1228
1229                 return "'" . pg_escape_string( $conn, $s ) . "'";
1230         }
1231
1232         /**
1233          * Postgres specific version of replaceVars.
1234          * Calls the parent version in Database.php
1235          *
1236          * @param string $ins SQL string, read from a stream (usually tables.sql)
1237          * @return string SQL string
1238          */
1239         protected function replaceVars( $ins ) {
1240                 $ins = parent::replaceVars( $ins );
1241
1242                 if ( $this->numericVersion >= 8.3 ) {
1243                         // Thanks for not providing backwards-compatibility, 8.3
1244                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1245                 }
1246
1247                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1248                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1249                 }
1250
1251                 return $ins;
1252         }
1253
1254         public function makeSelectOptions( $options ) {
1255                 $preLimitTail = $postLimitTail = '';
1256                 $startOpts = $useIndex = $ignoreIndex = '';
1257
1258                 $noKeyOptions = [];
1259                 foreach ( $options as $key => $option ) {
1260                         if ( is_numeric( $key ) ) {
1261                                 $noKeyOptions[$option] = true;
1262                         }
1263                 }
1264
1265                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1266
1267                 $preLimitTail .= $this->makeOrderBy( $options );
1268
1269                 if ( isset( $options['FOR UPDATE'] ) ) {
1270                         $postLimitTail .= ' FOR UPDATE OF ' .
1271                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1272                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1273                         $postLimitTail .= ' FOR UPDATE';
1274                 }
1275
1276                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1277                         $startOpts .= 'DISTINCT';
1278                 }
1279
1280                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1281         }
1282
1283         public function getDBname() {
1284                 return $this->mDBname;
1285         }
1286
1287         public function getServer() {
1288                 return $this->mServer;
1289         }
1290
1291         public function buildConcat( $stringList ) {
1292                 return implode( ' || ', $stringList );
1293         }
1294
1295         public function buildGroupConcatField(
1296                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1297         ) {
1298                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1299
1300                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1301         }
1302
1303         public function buildStringCast( $field ) {
1304                 return $field . '::text';
1305         }
1306
1307         public function streamStatementEnd( &$sql, &$newLine ) {
1308                 # Allow dollar quoting for function declarations
1309                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1310                         if ( $this->delimiter ) {
1311                                 $this->delimiter = false;
1312                         } else {
1313                                 $this->delimiter = ';';
1314                         }
1315                 }
1316
1317                 return parent::streamStatementEnd( $sql, $newLine );
1318         }
1319
1320         public function doLockTables( array $read, array $write, $method ) {
1321                 $tablesWrite = [];
1322                 foreach ( $write as $table ) {
1323                         $tablesWrite[] = $this->tableName( $table );
1324                 }
1325                 $tablesRead = [];
1326                 foreach ( $read as $table ) {
1327                         $tablesRead[] = $this->tableName( $table );
1328                 }
1329
1330                 // Acquire locks for the duration of the current transaction...
1331                 if ( $tablesWrite ) {
1332                         $this->query(
1333                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1334                                 $method
1335                         );
1336                 }
1337                 if ( $tablesRead ) {
1338                         $this->query(
1339                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1340                                 $method
1341                         );
1342                 }
1343
1344                 return true;
1345         }
1346
1347         public function lockIsFree( $lockName, $method ) {
1348                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1349                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1350                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1351                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1352                 $row = $this->fetchObject( $result );
1353
1354                 return ( $row->lockstatus === 't' );
1355         }
1356
1357         public function lock( $lockName, $method, $timeout = 5 ) {
1358                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1359                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1360                 $loop = new WaitConditionLoop(
1361                         function () use ( $lockName, $key, $timeout, $method ) {
1362                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1363                                 $row = $this->fetchObject( $res );
1364                                 if ( $row->lockstatus === 't' ) {
1365                                         parent::lock( $lockName, $method, $timeout ); // record
1366                                         return true;
1367                                 }
1368
1369                                 return WaitConditionLoop::CONDITION_CONTINUE;
1370                         },
1371                         $timeout
1372                 );
1373
1374                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1375         }
1376
1377         public function unlock( $lockName, $method ) {
1378                 // http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1379                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1380                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1381                 $row = $this->fetchObject( $result );
1382
1383                 if ( $row->lockstatus === 't' ) {
1384                         parent::unlock( $lockName, $method ); // record
1385                         return true;
1386                 }
1387
1388                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1389
1390                 return false;
1391         }
1392
1393         public function serverIsReadOnly() {
1394                 $res = $this->query( "SHOW default_transaction_read_only", __METHOD__ );
1395                 $row = $this->fetchObject( $res );
1396
1397                 return $row ? ( strtolower( $row->default_transaction_read_only ) === 'on' ) : false;
1398         }
1399
1400         /**
1401          * @param string $lockName
1402          * @return string Integer
1403          */
1404         private function bigintFromLockName( $lockName ) {
1405                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1406         }
1407 }
1408
1409 class_alias( DatabasePostgres::class, 'DatabasePostgres' );