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
  40         /** @var float|string */
  41         private $numericVersion = null;
  42         /** @var string Connect string to open a PostgreSQL connection */
  43         private $connectString;
  44         /** @var string */
  45         private $coreSchema;
  46         /** @var string */
  47         private $tempSchema;
  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                 foreach ( $this->getCoreSchemas() as $schema ) {
  79                         $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  80                                 "WHERE c.connamespace = n.oid AND conname = " .
  81                                 $this->addQuotes( $name ) . " AND n.nspname = " .
  82                                 $this->addQuotes( $schema );
  83                         $res = $this->doQuery( $sql );
  84                         if ( $res && $this->numRows( $res ) ) {
  85                                 return true;
  86                         }
  87                 }
  88                 return false;
  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->server = $server;
 103                 $this->user = $user;
 104                 $this->password = $password;
 105                 $this->dbName = $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->flags & 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->conn = 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->conn ) {
 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->opened = 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                 $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 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                 if ( pg_result_error( $this->lastResultHandle ) ) {
 223                         return false;
 224                 }
 225
 226                 return $this->lastResultHandle;
 227         }
 228
 229         protected function dumpError() {
 230                 $diags = [
 231                         PGSQL_DIAG_SEVERITY,
 232                         PGSQL_DIAG_SQLSTATE,
 233                         PGSQL_DIAG_MESSAGE_PRIMARY,
 234                         PGSQL_DIAG_MESSAGE_DETAIL,
 235                         PGSQL_DIAG_MESSAGE_HINT,
 236                         PGSQL_DIAG_STATEMENT_POSITION,
 237                         PGSQL_DIAG_INTERNAL_POSITION,
 238                         PGSQL_DIAG_INTERNAL_QUERY,
 239                         PGSQL_DIAG_CONTEXT,
 240                         PGSQL_DIAG_SOURCE_FILE,
 241                         PGSQL_DIAG_SOURCE_LINE,
 242                         PGSQL_DIAG_SOURCE_FUNCTION
 243                 ];
 244                 foreach ( $diags as $d ) {
 245                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 246                                 $d, pg_result_error_field( $this->lastResultHandle, $d ) ) );
 247                 }
 248         }
 249
 250         public function freeResult( $res ) {
 251                 if ( $res instanceof ResultWrapper ) {
 252                         $res = $res->result;
 253                 }
 254                 Wikimedia\suppressWarnings();
 255                 $ok = pg_free_result( $res );
 256                 Wikimedia\restoreWarnings();
 257                 if ( !$ok ) {
 258                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 259                 }
 260         }
 261
 262         public function fetchObject( $res ) {
 263                 if ( $res instanceof ResultWrapper ) {
 264                         $res = $res->result;
 265                 }
 266                 Wikimedia\suppressWarnings();
 267                 $row = pg_fetch_object( $res );
 268                 Wikimedia\restoreWarnings();
 269                 # @todo FIXME: HACK HACK HACK HACK debug
 270
 271                 # @todo hashar: not sure if the following test really trigger if the object
 272                 #          fetching failed.
 273                 $conn = $this->getBindingHandle();
 274                 if ( pg_last_error( $conn ) ) {
 275                         throw new DBUnexpectedError(
 276                                 $this,
 277                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 278                         );
 279                 }
 280
 281                 return $row;
 282         }
 283
 284         public function fetchRow( $res ) {
 285                 if ( $res instanceof ResultWrapper ) {
 286                         $res = $res->result;
 287                 }
 288                 Wikimedia\suppressWarnings();
 289                 $row = pg_fetch_array( $res );
 290                 Wikimedia\restoreWarnings();
 291
 292                 $conn = $this->getBindingHandle();
 293                 if ( pg_last_error( $conn ) ) {
 294                         throw new DBUnexpectedError(
 295                                 $this,
 296                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 297                         );
 298                 }
 299
 300                 return $row;
 301         }
 302
 303         public function numRows( $res ) {
 304                 if ( $res instanceof ResultWrapper ) {
 305                         $res = $res->result;
 306                 }
 307                 Wikimedia\suppressWarnings();
 308                 $n = pg_num_rows( $res );
 309                 Wikimedia\restoreWarnings();
 310
 311                 $conn = $this->getBindingHandle();
 312                 if ( pg_last_error( $conn ) ) {
 313                         throw new DBUnexpectedError(
 314                                 $this,
 315                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 316                         );
 317                 }
 318
 319                 return $n;
 320         }
 321
 322         public function numFields( $res ) {
 323                 if ( $res instanceof ResultWrapper ) {
 324                         $res = $res->result;
 325                 }
 326
 327                 return pg_num_fields( $res );
 328         }
 329
 330         public function fieldName( $res, $n ) {
 331                 if ( $res instanceof ResultWrapper ) {
 332                         $res = $res->result;
 333                 }
 334
 335                 return pg_field_name( $res, $n );
 336         }
 337
 338         public function insertId() {
 339                 $res = $this->query( "SELECT lastval()" );
 340                 $row = $this->fetchRow( $res );
 341                 return is_null( $row[0] ) ? null : (int)$row[0];
 342         }
 343
 344         public function dataSeek( $res, $row ) {
 345                 if ( $res instanceof ResultWrapper ) {
 346                         $res = $res->result;
 347                 }
 348
 349                 return pg_result_seek( $res, $row );
 350         }
 351
 352         public function lastError() {
 353                 if ( $this->conn ) {
 354                         if ( $this->lastResultHandle ) {
 355                                 return pg_result_error( $this->lastResultHandle );
 356                         } else {
 357                                 return pg_last_error();
 358                         }
 359                 }
 360
 361                 return $this->getLastPHPError() ?: 'No database connection';
 362         }
 363
 364         public function lastErrno() {
 365                 if ( $this->lastResultHandle ) {
 366                         return pg_result_error_field( $this->lastResultHandle, PGSQL_DIAG_SQLSTATE );
 367                 } else {
 368                         return false;
 369                 }
 370         }
 371
 372         protected function fetchAffectedRowCount() {
 373                 if ( !$this->lastResultHandle ) {
 374                         return 0;
 375                 }
 376
 377                 return pg_affected_rows( $this->lastResultHandle );
 378         }
 379
 380         /**
 381          * Estimate rows in dataset
 382          * Returns estimated count, based on EXPLAIN output
 383          * This is not necessarily an accurate estimate, so use sparingly
 384          * Returns -1 if count cannot be found
 385          * Takes same arguments as Database::select()
 386          *
 387          * @param string $table
 388          * @param string $var
 389          * @param string $conds
 390          * @param string $fname
 391          * @param array $options
 392          * @param array $join_conds
 393          * @return int
 394          */
 395         public function estimateRowCount( $table, $var = '*', $conds = '',
 396                 $fname = __METHOD__, $options = [], $join_conds = []
 397         ) {
 398                 $conds = $this->normalizeConditions( $conds, $fname );
 399                 $column = $this->extractSingleFieldFromList( $var );
 400                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 401                         $conds[] = "$column IS NOT NULL";
 402                 }
 403
 404                 $options['EXPLAIN'] = true;
 405                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 406                 $rows = -1;
 407                 if ( $res ) {
 408                         $row = $this->fetchRow( $res );
 409                         $count = [];
 410                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 411                                 $rows = (int)$count[1];
 412                         }
 413                 }
 414
 415                 return $rows;
 416         }
 417
 418         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 419                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 420                 $res = $this->query( $sql, $fname );
 421                 if ( !$res ) {
 422                         return null;
 423                 }
 424                 foreach ( $res as $row ) {
 425                         if ( $row->indexname == $this->indexName( $index ) ) {
 426                                 return $row;
 427                         }
 428                 }
 429
 430                 return false;
 431         }
 432
 433         public function indexAttributes( $index, $schema = false ) {
 434                 if ( $schema === false ) {
 435                         $schemas = $this->getCoreSchemas();
 436                 } else {
 437                         $schemas = [ $schema ];
 438                 }
 439
 440                 $eindex = $this->addQuotes( $index );
 441
 442                 foreach ( $schemas as $schema ) {
 443                         $eschema = $this->addQuotes( $schema );
 444                         /*
 445                          * A subquery would be not needed if we didn't care about the order
 446                          * of attributes, but we do
 447                          */
 448                         $sql = <<<__INDEXATTR__
 449
 450                                 SELECT opcname,
 451                                         attname,
 452                                         i.indoption[s.g] as option,
 453                                         pg_am.amname
 454                                 FROM
 455                                         (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 456                                                 FROM
 457                                                         pg_index isub
 458                                                 JOIN pg_class cis
 459                                                         ON cis.oid=isub.indexrelid
 460                                                 JOIN pg_namespace ns
 461                                                         ON cis.relnamespace = ns.oid
 462                                                 WHERE cis.relname=$eindex AND ns.nspname=$eschema) AS s,
 463                                         pg_attribute,
 464                                         pg_opclass opcls,
 465                                         pg_am,
 466                                         pg_class ci
 467                                         JOIN pg_index i
 468                                                 ON ci.oid=i.indexrelid
 469                                         JOIN pg_class ct
 470                                                 ON ct.oid = i.indrelid
 471                                         JOIN pg_namespace n
 472                                                 ON ci.relnamespace = n.oid
 473                                         WHERE
 474                                                 ci.relname=$eindex AND n.nspname=$eschema
 475                                                 AND     attrelid = ct.oid
 476                                                 AND     i.indkey[s.g] = attnum
 477                                                 AND     i.indclass[s.g] = opcls.oid
 478                                                 AND     pg_am.oid = opcls.opcmethod
 479 __INDEXATTR__;
 480                         $res = $this->query( $sql, __METHOD__ );
 481                         $a = [];
 482                         if ( $res ) {
 483                                 foreach ( $res as $row ) {
 484                                         $a[] = [
 485                                                 $row->attname,
 486                                                 $row->opcname,
 487                                                 $row->amname,
 488                                                 $row->option ];
 489                                 }
 490                                 return $a;
 491                         }
 492                 }
 493                 return null;
 494         }
 495
 496         public function indexUnique( $table, $index, $fname = __METHOD__ ) {
 497                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 498                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 499                         $this->strencode( $this->indexName( $index ) ) .
 500                         ")'";
 501                 $res = $this->query( $sql, $fname );
 502                 if ( !$res ) {
 503                         return null;
 504                 }
 505
 506                 return $res->numRows() > 0;
 507         }
 508
 509         public function selectSQLText(
 510                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 511         ) {
 512                 if ( is_string( $options ) ) {
 513                         $options = [ $options ];
 514                 }
 515
 516                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 517                 // to the parent function to get the actual SQL text.
 518                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 519                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 520                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 521                 // accordingly.
 522                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 523                 if ( is_array( $options ) ) {
 524                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 525                         if ( $forUpdateKey !== false && $join_conds ) {
 526                                 unset( $options[$forUpdateKey] );
 527                                 $options['FOR UPDATE'] = [];
 528
 529                                 $toCheck = $table;
 530                                 reset( $toCheck );
 531                                 while ( $toCheck ) {
 532                                         $alias = key( $toCheck );
 533                                         $name = $toCheck[$alias];
 534                                         unset( $toCheck[$alias] );
 535
 536                                         $hasAlias = !is_numeric( $alias );
 537                                         if ( !$hasAlias && is_string( $name ) ) {
 538                                                 $alias = $name;
 539                                         }
 540
 541                                         if ( !isset( $join_conds[$alias] ) ||
 542                                                 !preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_conds[$alias][0] )
 543                                         ) {
 544                                                 if ( is_array( $name ) ) {
 545                                                         // It's a parenthesized group, process all the tables inside the group.
 546                                                         $toCheck = array_merge( $toCheck, $name );
 547                                                 } else {
 548                                                         // Quote alias names so $this->tableName() won't mangle them
 549                                                         $options['FOR UPDATE'][] = $hasAlias ? $this->addIdentifierQuotes( $alias ) : $alias;
 550                                                 }
 551                                         }
 552                                 }
 553                         }
 554
 555                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 556                                 unset( $options['ORDER BY'] );
 557                         }
 558                 }
 559
 560                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 561         }
 562
 563         /** @inheritDoc */
 564         public function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 565                 if ( !count( $args ) ) {
 566                         return true;
 567                 }
 568
 569                 $table = $this->tableName( $table );
 570                 if ( !isset( $this->numericVersion ) ) {
 571                         $this->getServerVersion();
 572                 }
 573
 574                 if ( !is_array( $options ) ) {
 575                         $options = [ $options ];
 576                 }
 577
 578                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 579                         $rows = $args;
 580                         $keys = array_keys( $args[0] );
 581                 } else {
 582                         $rows = [ $args ];
 583                         $keys = array_keys( $args );
 584                 }
 585
 586                 $ignore = in_array( 'IGNORE', $options );
 587
 588                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 589
 590                 if ( $this->numericVersion >= 9.5 || !$ignore ) {
 591                         // No IGNORE or our PG has "ON CONFLICT DO NOTHING"
 592                         $first = true;
 593                         foreach ( $rows as $row ) {
 594                                 if ( $first ) {
 595                                         $first = false;
 596                                 } else {
 597                                         $sql .= ',';
 598                                 }
 599                                 $sql .= '(' . $this->makeList( $row ) . ')';
 600                         }
 601                         if ( $ignore ) {
 602                                 $sql .= ' ON CONFLICT DO NOTHING';
 603                         }
 604                         $this->query( $sql, $fname );
 605                 } else {
 606                         // Emulate IGNORE by doing each row individually, with savepoints
 607                         // to roll back as necessary.
 608                         $numrowsinserted = 0;
 609
 610                         $tok = $this->startAtomic( "$fname (outer)", self::ATOMIC_CANCELABLE );
 611                         try {
 612                                 foreach ( $rows as $row ) {
 613                                         $tempsql = $sql;
 614                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 615
 616                                         $this->startAtomic( "$fname (inner)", self::ATOMIC_CANCELABLE );
 617                                         try {
 618                                                 $this->query( $tempsql, $fname );
 619                                                 $this->endAtomic( "$fname (inner)" );
 620                                                 $numrowsinserted++;
 621                                         } catch ( DBQueryError $e ) {
 622                                                 $this->cancelAtomic( "$fname (inner)" );
 623                                                 // Our IGNORE is supposed to ignore duplicate key errors, but not others.
 624                                                 // (even though MySQL's version apparently ignores all errors)
 625                                                 if ( $e->errno !== '23505' ) {
 626                                                         throw $e;
 627                                                 }
 628                                         }
 629                                 }
 630                         } catch ( Exception $e ) {
 631                                 $this->cancelAtomic( "$fname (outer)", $tok );
 632                                 throw $e;
 633                         }
 634                         $this->endAtomic( "$fname (outer)" );
 635
 636                         // Set the affected row count for the whole operation
 637                         $this->affectedRowCount = $numrowsinserted;
 638                 }
 639
 640                 return true;
 641         }
 642
 643         /**
 644          * INSERT SELECT wrapper
 645          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 646          * Source items may be literals rather then field names, but strings should
 647          * be quoted with Database::addQuotes()
 648          * $conds may be "*" to copy the whole table
 649          * srcTable may be an array of tables.
 650          * @todo FIXME: Implement this a little better (seperate select/insert)?
 651          *
 652          * @param string $destTable
 653          * @param array|string $srcTable
 654          * @param array $varMap
 655          * @param array $conds
 656          * @param string $fname
 657          * @param array $insertOptions
 658          * @param array $selectOptions
 659          * @param array $selectJoinConds
 660          * @return bool
 661          */
 662         public function nativeInsertSelect(
 663                 $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 664                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 665         ) {
 666                 if ( !is_array( $insertOptions ) ) {
 667                         $insertOptions = [ $insertOptions ];
 668                 }
 669
 670                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 671                         if ( $this->getServerVersion() >= 9.5 ) {
 672                                 // Use ON CONFLICT DO NOTHING if we have it for IGNORE
 673                                 $destTable = $this->tableName( $destTable );
 674
 675                                 $selectSql = $this->selectSQLText(
 676                                         $srcTable,
 677                                         array_values( $varMap ),
 678                                         $conds,
 679                                         $fname,
 680                                         $selectOptions,
 681                                         $selectJoinConds
 682                                 );
 683
 684                                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ') ' .
 685                                         $selectSql . ' ON CONFLICT DO NOTHING';
 686
 687                                 return $this->query( $sql, $fname );
 688                         } else {
 689                                 // IGNORE and we don't have ON CONFLICT DO NOTHING, so just use the non-native version
 690                                 return $this->nonNativeInsertSelect(
 691                                         $destTable, $srcTable, $varMap, $conds, $fname,
 692                                         $insertOptions, $selectOptions, $selectJoinConds
 693                                 );
 694                         }
 695                 }
 696
 697                 return parent::nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname,
 698                         $insertOptions, $selectOptions, $selectJoinConds );
 699         }
 700
 701         public function tableName( $name, $format = 'quoted' ) {
 702                 // Replace reserved words with better ones
 703                 $name = $this->remappedTableName( $name );
 704
 705                 return parent::tableName( $name, $format );
 706         }
 707
 708         /**
 709          * @param string $name
 710          * @return string Value of $name or remapped name if $name is a reserved keyword
 711          */
 712         public function remappedTableName( $name ) {
 713                 return isset( $this->keywordTableMap[$name] ) ? $this->keywordTableMap[$name] : $name;
 714         }
 715
 716         /**
 717          * @param string $name
 718          * @param string $format
 719          * @return string Qualified and encoded (if requested) table name
 720          */
 721         public function realTableName( $name, $format = 'quoted' ) {
 722                 return parent::tableName( $name, $format );
 723         }
 724
 725         public function nextSequenceValue( $seqName ) {
 726                 return new NextSequenceValue;
 727         }
 728
 729         /**
 730          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 731          *
 732          * @param string $seqName
 733          * @return int
 734          */
 735         public function currentSequenceValue( $seqName ) {
 736                 $safeseq = str_replace( "'", "''", $seqName );
 737                 $res = $this->query( "SELECT currval('$safeseq')" );
 738                 $row = $this->fetchRow( $res );
 739                 $currval = $row[0];
 740
 741                 return $currval;
 742         }
 743
 744         public function textFieldSize( $table, $field ) {
 745                 $table = $this->tableName( $table );
 746                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 747                         FROM pg_class c, pg_attribute a, pg_type t
 748                         WHERE relname='$table' AND a.attrelid=c.oid AND
 749                                 a.atttypid=t.oid and a.attname='$field'";
 750                 $res = $this->query( $sql );
 751                 $row = $this->fetchObject( $res );
 752                 if ( $row->ftype == 'varchar' ) {
 753                         $size = $row->size - 4;
 754                 } else {
 755                         $size = $row->size;
 756                 }
 757
 758                 return $size;
 759         }
 760
 761         public function limitResult( $sql, $limit, $offset = false ) {
 762                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 763         }
 764
 765         public function wasDeadlock() {
 766                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 767                 return $this->lastErrno() === '40P01';
 768         }
 769
 770         public function wasLockTimeout() {
 771                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 772                 return $this->lastErrno() === '55P03';
 773         }
 774
 775         public function wasConnectionError( $errno ) {
 776                 // https://www.postgresql.org/docs/9.2/static/errcodes-appendix.html
 777                 static $codes = [ '08000', '08003', '08006', '08001', '08004', '57P01', '57P03', '53300' ];
 778
 779                 return in_array( $errno, $codes, true );
 780         }
 781
 782         protected function wasKnownStatementRollbackError() {
 783                 return false; // transaction has to be rolled-back from error state
 784         }
 785
 786         public function duplicateTableStructure(
 787                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 788         ) {
 789                 $newName = $this->addIdentifierQuotes( $newName );
 790                 $oldName = $this->addIdentifierQuotes( $oldName );
 791
 792                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 793                         "(LIKE $oldName INCLUDING DEFAULTS INCLUDING INDEXES)", $fname );
 794         }
 795
 796         public function listTables( $prefix = null, $fname = __METHOD__ ) {
 797                 $eschemas = implode( ',', array_map( [ $this, 'addQuotes' ], $this->getCoreSchemas() ) );
 798                 $result = $this->query(
 799                         "SELECT DISTINCT tablename FROM pg_tables WHERE schemaname IN ($eschemas)", $fname );
 800                 $endArray = [];
 801
 802                 foreach ( $result as $table ) {
 803                         $vars = get_object_vars( $table );
 804                         $table = array_pop( $vars );
 805                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 806                                 $endArray[] = $table;
 807                         }
 808                 }
 809
 810                 return $endArray;
 811         }
 812
 813         public function timestamp( $ts = 0 ) {
 814                 $ct = new ConvertibleTimestamp( $ts );
 815
 816                 return $ct->getTimestamp( TS_POSTGRES );
 817         }
 818
 819         /**
 820          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 821          * to https://secure.php.net/manual/en/ref.pgsql.php
 822          *
 823          * Parsing a postgres array can be a tricky problem, he's my
 824          * take on this, it handles multi-dimensional arrays plus
 825          * escaping using a nasty regexp to determine the limits of each
 826          * data-item.
 827          *
 828          * This should really be handled by PHP PostgreSQL module
 829          *
 830          * @since 1.19
 831          * @param string $text Postgreql array returned in a text form like {a,b}
 832          * @param string[] $output
 833          * @param int|bool $limit
 834          * @param int $offset
 835          * @return string[]
 836          */
 837         private function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 838                 if ( false === $limit ) {
 839                         $limit = strlen( $text ) - 1;
 840                         $output = [];
 841                 }
 842                 if ( '{}' == $text ) {
 843                         return $output;
 844                 }
 845                 do {
 846                         if ( '{' != $text[$offset] ) {
 847                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 848                                         $text, $match, 0, $offset );
 849                                 $offset += strlen( $match[0] );
 850                                 $output[] = ( '"' != $match[1][0]
 851                                         ? $match[1]
 852                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 853                                 if ( '},' == $match[3] ) {
 854                                         return $output;
 855                                 }
 856                         } else {
 857                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 858                         }
 859                 } while ( $limit > $offset );
 860
 861                 return $output;
 862         }
 863
 864         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 865                 return $valuedata;
 866         }
 867
 868         public function getSoftwareLink() {
 869                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 870         }
 871
 872         /**
 873          * Return current schema (executes SELECT current_schema())
 874          * Needs transaction
 875          *
 876          * @since 1.19
 877          * @return string Default schema for the current session
 878          */
 879         public function getCurrentSchema() {
 880                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 881                 $row = $this->fetchRow( $res );
 882
 883                 return $row[0];
 884         }
 885
 886         /**
 887          * Return list of schemas which are accessible without schema name
 888          * This is list does not contain magic keywords like "$user"
 889          * Needs transaction
 890          *
 891          * @see getSearchPath()
 892          * @see setSearchPath()
 893          * @since 1.19
 894          * @return array List of actual schemas for the current sesson
 895          */
 896         public function getSchemas() {
 897                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 898                 $row = $this->fetchRow( $res );
 899                 $schemas = [];
 900
 901                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 902
 903                 return $this->pg_array_parse( $row[0], $schemas );
 904         }
 905
 906         /**
 907          * Return search patch for schemas
 908          * This is different from getSchemas() since it contain magic keywords
 909          * (like "$user").
 910          * Needs transaction
 911          *
 912          * @since 1.19
 913          * @return array How to search for table names schemas for the current user
 914          */
 915         public function getSearchPath() {
 916                 $res = $this->query( "SHOW search_path", __METHOD__ );
 917                 $row = $this->fetchRow( $res );
 918
 919                 /* PostgreSQL returns SHOW values as strings */
 920
 921                 return explode( ",", $row[0] );
 922         }
 923
 924         /**
 925          * Update search_path, values should already be sanitized
 926          * Values may contain magic keywords like "$user"
 927          * @since 1.19
 928          *
 929          * @param array $search_path List of schemas to be searched by default
 930          */
 931         private function setSearchPath( $search_path ) {
 932                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 933         }
 934
 935         /**
 936          * Determine default schema for the current application
 937          * Adjust this session schema search path if desired schema exists
 938          * and is not alread there.
 939          *
 940          * We need to have name of the core schema stored to be able
 941          * to query database metadata.
 942          *
 943          * This will be also called by the installer after the schema is created
 944          *
 945          * @since 1.19
 946          *
 947          * @param string $desiredSchema
 948          */
 949         public function determineCoreSchema( $desiredSchema ) {
 950                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
 951                 if ( $this->schemaExists( $desiredSchema ) ) {
 952                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
 953                                 $this->coreSchema = $desiredSchema;
 954                                 $this->queryLogger->debug(
 955                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
 956                         } else {
 957                                 /**
 958                                  * Prepend our schema (e.g. 'mediawiki') in front
 959                                  * of the search path
 960                                  * Fixes T17816
 961                                  */
 962                                 $search_path = $this->getSearchPath();
 963                                 array_unshift( $search_path,
 964                                         $this->addIdentifierQuotes( $desiredSchema ) );
 965                                 $this->setSearchPath( $search_path );
 966                                 $this->coreSchema = $desiredSchema;
 967                                 $this->queryLogger->debug(
 968                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
 969                         }
 970                 } else {
 971                         $this->coreSchema = $this->getCurrentSchema();
 972                         $this->queryLogger->debug(
 973                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
 974                                 $this->coreSchema . "\"\n" );
 975                 }
 976                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
 977                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
 978         }
 979
 980         /**
 981          * Return schema name for core application tables
 982          *
 983          * @since 1.19
 984          * @return string Core schema name
 985          */
 986         public function getCoreSchema() {
 987                 return $this->coreSchema;
 988         }
 989
 990         /**
 991          * Return schema names for temporary tables and core application tables
 992          *
 993          * @since 1.31
 994          * @return string[] schema names
 995          */
 996         public function getCoreSchemas() {
 997                 if ( $this->tempSchema ) {
 998                         return [ $this->tempSchema, $this->getCoreSchema() ];
 999                 }
1000
1001                 $res = $this->query(
1002                         "SELECT nspname FROM pg_catalog.pg_namespace n WHERE n.oid = pg_my_temp_schema()", __METHOD__
1003                 );
1004                 $row = $this->fetchObject( $res );
1005                 if ( $row ) {
1006                         $this->tempSchema = $row->nspname;
1007                         return [ $this->tempSchema, $this->getCoreSchema() ];
1008                 }
1009
1010                 return [ $this->getCoreSchema() ];
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                         $schemas = $this->getCoreSchemas();
1046                 } else {
1047                         $schemas = [ $schema ];
1048                 }
1049                 $table = $this->realTableName( $table, 'raw' );
1050                 $etable = $this->addQuotes( $table );
1051                 foreach ( $schemas as $schema ) {
1052                         $eschema = $this->addQuotes( $schema );
1053                         $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1054                                 . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1055                                 . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1056                         $res = $this->query( $sql );
1057                         if ( $res && $res->numRows() ) {
1058                                 return true;
1059                         }
1060                 }
1061
1062                 return false;
1063         }
1064
1065         /**
1066          * For backward compatibility, this function checks both tables and views.
1067          * @param string $table
1068          * @param string $fname
1069          * @param bool|string $schema
1070          * @return bool
1071          */
1072         public function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1073                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1074         }
1075
1076         public function sequenceExists( $sequence, $schema = false ) {
1077                 return $this->relationExists( $sequence, 'S', $schema );
1078         }
1079
1080         public function triggerExists( $table, $trigger ) {
1081                 $q = <<<SQL
1082         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1083                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1084                         AND tgrelid=pg_class.oid
1085                         AND nspname=%s AND relname=%s AND tgname=%s
1086 SQL;
1087                 foreach ( $this->getCoreSchemas() as $schema ) {
1088                         $res = $this->query(
1089                                 sprintf(
1090                                         $q,
1091                                         $this->addQuotes( $schema ),
1092                                         $this->addQuotes( $table ),
1093                                         $this->addQuotes( $trigger )
1094                                 )
1095                         );
1096                         if ( $res && $res->numRows() ) {
1097                                 return true;
1098                         }
1099                 }
1100
1101                 return false;
1102         }
1103
1104         public function ruleExists( $table, $rule ) {
1105                 $exists = $this->selectField( 'pg_rules', 'rulename',
1106                         [
1107                                 'rulename' => $rule,
1108                                 'tablename' => $table,
1109                                 'schemaname' => $this->getCoreSchemas()
1110                         ]
1111                 );
1112
1113                 return $exists === $rule;
1114         }
1115
1116         public function constraintExists( $table, $constraint ) {
1117                 foreach ( $this->getCoreSchemas() as $schema ) {
1118                         $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1119                                 "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1120                                 $this->addQuotes( $schema ),
1121                                 $this->addQuotes( $table ),
1122                                 $this->addQuotes( $constraint )
1123                         );
1124                         $res = $this->query( $sql );
1125                         if ( $res && $res->numRows() ) {
1126                                 return true;
1127                         }
1128                 }
1129                 return false;
1130         }
1131
1132         /**
1133          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1134          * @param string $schema
1135          * @return bool
1136          */
1137         public function schemaExists( $schema ) {
1138                 if ( !strlen( $schema ) ) {
1139                         return false; // short-circuit
1140                 }
1141
1142                 $exists = $this->selectField(
1143                         '"pg_catalog"."pg_namespace"', 1, [ 'nspname' => $schema ], __METHOD__ );
1144
1145                 return (bool)$exists;
1146         }
1147
1148         /**
1149          * Returns true if a given role (i.e. user) exists, false otherwise.
1150          * @param string $roleName
1151          * @return bool
1152          */
1153         public function roleExists( $roleName ) {
1154                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1155                         [ 'rolname' => $roleName ], __METHOD__ );
1156
1157                 return (bool)$exists;
1158         }
1159
1160         /**
1161          * @param string $table
1162          * @param string $field
1163          * @return PostgresField|null
1164          */
1165         public function fieldInfo( $table, $field ) {
1166                 return PostgresField::fromText( $this, $table, $field );
1167         }
1168
1169         /**
1170          * pg_field_type() wrapper
1171          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1172          * @param int $index Field number, starting from 0
1173          * @return string
1174          */
1175         public function fieldType( $res, $index ) {
1176                 if ( $res instanceof ResultWrapper ) {
1177                         $res = $res->result;
1178                 }
1179
1180                 return pg_field_type( $res, $index );
1181         }
1182
1183         public function encodeBlob( $b ) {
1184                 return new PostgresBlob( pg_escape_bytea( $b ) );
1185         }
1186
1187         public function decodeBlob( $b ) {
1188                 if ( $b instanceof PostgresBlob ) {
1189                         $b = $b->fetch();
1190                 } elseif ( $b instanceof Blob ) {
1191                         return $b->fetch();
1192                 }
1193
1194                 return pg_unescape_bytea( $b );
1195         }
1196
1197         public function strencode( $s ) {
1198                 // Should not be called by us
1199                 return pg_escape_string( $this->getBindingHandle(), (string)$s );
1200         }
1201
1202         public function addQuotes( $s ) {
1203                 $conn = $this->getBindingHandle();
1204
1205                 if ( is_null( $s ) ) {
1206                         return 'NULL';
1207                 } elseif ( is_bool( $s ) ) {
1208                         return intval( $s );
1209                 } elseif ( $s instanceof Blob ) {
1210                         if ( $s instanceof PostgresBlob ) {
1211                                 $s = $s->fetch();
1212                         } else {
1213                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1214                         }
1215                         return "'$s'";
1216                 } elseif ( $s instanceof NextSequenceValue ) {
1217                         return 'DEFAULT';
1218                 }
1219
1220                 return "'" . pg_escape_string( $conn, (string)$s ) . "'";
1221         }
1222
1223         public function makeSelectOptions( $options ) {
1224                 $preLimitTail = $postLimitTail = '';
1225                 $startOpts = $useIndex = $ignoreIndex = '';
1226
1227                 $noKeyOptions = [];
1228                 foreach ( $options as $key => $option ) {
1229                         if ( is_numeric( $key ) ) {
1230                                 $noKeyOptions[$option] = true;
1231                         }
1232                 }
1233
1234                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1235
1236                 $preLimitTail .= $this->makeOrderBy( $options );
1237
1238                 if ( isset( $options['FOR UPDATE'] ) ) {
1239                         $postLimitTail .= ' FOR UPDATE OF ' .
1240                                 implode( ', ', array_map( [ $this, 'tableName' ], $options['FOR UPDATE'] ) );
1241                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1242                         $postLimitTail .= ' FOR UPDATE';
1243                 }
1244
1245                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1246                         $startOpts .= 'DISTINCT';
1247                 }
1248
1249                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1250         }
1251
1252         public function getDBname() {
1253                 return $this->dbName;
1254         }
1255
1256         public function getServer() {
1257                 return $this->server;
1258         }
1259
1260         public function buildConcat( $stringList ) {
1261                 return implode( ' || ', $stringList );
1262         }
1263
1264         public function buildGroupConcatField(
1265                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1266         ) {
1267                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1268
1269                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1270         }
1271
1272         public function buildStringCast( $field ) {
1273                 return $field . '::text';
1274         }
1275
1276         public function streamStatementEnd( &$sql, &$newLine ) {
1277                 # Allow dollar quoting for function declarations
1278                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1279                         if ( $this->delimiter ) {
1280                                 $this->delimiter = false;
1281                         } else {
1282                                 $this->delimiter = ';';
1283                         }
1284                 }
1285
1286                 return parent::streamStatementEnd( $sql, $newLine );
1287         }
1288
1289         public function doLockTables( array $read, array $write, $method ) {
1290                 $tablesWrite = [];
1291                 foreach ( $write as $table ) {
1292                         $tablesWrite[] = $this->tableName( $table );
1293                 }
1294                 $tablesRead = [];
1295                 foreach ( $read as $table ) {
1296                         $tablesRead[] = $this->tableName( $table );
1297                 }
1298
1299                 // Acquire locks for the duration of the current transaction...
1300                 if ( $tablesWrite ) {
1301                         $this->query(
1302                                 'LOCK TABLE ONLY ' . implode( ',', $tablesWrite ) . ' IN EXCLUSIVE MODE',
1303                                 $method
1304                         );
1305                 }
1306                 if ( $tablesRead ) {
1307                         $this->query(
1308                                 'LOCK TABLE ONLY ' . implode( ',', $tablesRead ) . ' IN SHARE MODE',
1309                                 $method
1310                         );
1311                 }
1312
1313                 return true;
1314         }
1315
1316         public function lockIsFree( $lockName, $method ) {
1317                 if ( !parent::lockIsFree( $lockName, $method ) ) {
1318                         return false; // already held
1319                 }
1320                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1321                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1322                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1323                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1324                 $row = $this->fetchObject( $result );
1325
1326                 return ( $row->lockstatus === 't' );
1327         }
1328
1329         public function lock( $lockName, $method, $timeout = 5 ) {
1330                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1331                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1332                 $loop = new WaitConditionLoop(
1333                         function () use ( $lockName, $key, $timeout, $method ) {
1334                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1335                                 $row = $this->fetchObject( $res );
1336                                 if ( $row->lockstatus === 't' ) {
1337                                         parent::lock( $lockName, $method, $timeout ); // record
1338                                         return true;
1339                                 }
1340
1341                                 return WaitConditionLoop::CONDITION_CONTINUE;
1342                         },
1343                         $timeout
1344                 );
1345
1346                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1347         }
1348
1349         public function unlock( $lockName, $method ) {
1350                 // http://www.postgresql.org/docs/9.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1351                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1352                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1353                 $row = $this->fetchObject( $result );
1354
1355                 if ( $row->lockstatus === 't' ) {
1356                         parent::unlock( $lockName, $method ); // record
1357                         return true;
1358                 }
1359
1360                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1361
1362                 return false;
1363         }
1364
1365         public function serverIsReadOnly() {
1366                 $res = $this->query( "SHOW default_transaction_read_only", __METHOD__ );
1367                 $row = $this->fetchObject( $res );
1368
1369                 return $row ? ( strtolower( $row->default_transaction_read_only ) === 'on' ) : false;
1370         }
1371
1372         /**
1373          * @param string $lockName
1374          * @return string Integer
1375          */
1376         private function bigintFromLockName( $lockName ) {
1377                 return \Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1378         }
1379 }
1380
1381 class_alias( DatabasePostgres::class, 'DatabasePostgres' );