includes/libs/rdbms/database/DatabasePostgres.php

   1 <?php
   2 /**
   3  * This is the Postgres database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  */
  23 use Wikimedia\WaitConditionLoop;
  24
  25 /**
  26  * @ingroup Database
  27  */
  28 class DatabasePostgres extends Database {
  29         /** @var int|bool */
  30         protected $port;
  31
  32         /** @var resource */
  33         protected $mLastResult = null;
  34         /** @var int The number of rows affected as an integer */
  35         protected $mAffectedRows = null;
  36
  37         /** @var int */
  38         private $mInsertId = null;
  39         /** @var float|string */
  40         private $numericVersion = null;
  41         /** @var string Connect string to open a PostgreSQL connection */
  42         private $connectString;
  43         /** @var string */
  44         private $mCoreSchema;
  45
  46         public function __construct( array $params ) {
  47                 $this->port = isset( $params['port'] ) ? $params['port'] : false;
  48                 parent::__construct( $params );
  49         }
  50
  51         function getType() {
  52                 return 'postgres';
  53         }
  54
  55         function implicitGroupby() {
  56                 return false;
  57         }
  58
  59         function implicitOrderby() {
  60                 return false;
  61         }
  62
  63         function hasConstraint( $name ) {
  64                 $conn = $this->getBindingHandle();
  65
  66                 $sql = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
  67                         "WHERE c.connamespace = n.oid AND conname = '" .
  68                         pg_escape_string( $conn, $name ) . "' AND n.nspname = '" .
  69                         pg_escape_string( $conn, $this->getCoreSchema() ) . "'";
  70                 $res = $this->doQuery( $sql );
  71
  72                 return $this->numRows( $res );
  73         }
  74
  75         /**
  76          * Usually aborts on failure
  77          * @param string $server
  78          * @param string $user
  79          * @param string $password
  80          * @param string $dbName
  81          * @throws DBConnectionError|Exception
  82          * @return resource|bool|null
  83          */
  84         function open( $server, $user, $password, $dbName ) {
  85                 # Test for Postgres support, to avoid suppressed fatal error
  86                 if ( !function_exists( 'pg_connect' ) ) {
  87                         throw new DBConnectionError(
  88                                 $this,
  89                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
  90                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
  91                                 "webserver and database)\n"
  92                         );
  93                 }
  94
  95                 $this->mServer = $server;
  96                 $this->mUser = $user;
  97                 $this->mPassword = $password;
  98                 $this->mDBname = $dbName;
  99
 100                 $connectVars = [
 101                         'dbname' => $dbName,
 102                         'user' => $user,
 103                         'password' => $password
 104                 ];
 105                 if ( $server != false && $server != '' ) {
 106                         $connectVars['host'] = $server;
 107                 }
 108                 if ( (int)$this->port > 0 ) {
 109                         $connectVars['port'] = (int)$this->port;
 110                 }
 111                 if ( $this->mFlags & self::DBO_SSL ) {
 112                         $connectVars['sslmode'] = 1;
 113                 }
 114
 115                 $this->connectString = $this->makeConnectionString( $connectVars );
 116                 $this->close();
 117                 $this->installErrorHandler();
 118
 119                 try {
 120                         // Use new connections to let LoadBalancer/LBFactory handle reuse
 121                         $this->mConn = pg_connect( $this->connectString, PGSQL_CONNECT_FORCE_NEW );
 122                 } catch ( Exception $ex ) {
 123                         $this->restoreErrorHandler();
 124                         throw $ex;
 125                 }
 126
 127                 $phpError = $this->restoreErrorHandler();
 128
 129                 if ( !$this->mConn ) {
 130                         $this->queryLogger->debug(
 131                                 "DB connection error\n" .
 132                                 "Server: $server, Database: $dbName, User: $user, Password: " .
 133                                 substr( $password, 0, 3 ) . "...\n"
 134                         );
 135                         $this->queryLogger->debug( $this->lastError() . "\n" );
 136                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 137                 }
 138
 139                 $this->mOpened = true;
 140
 141                 # If called from the command-line (e.g. importDump), only show errors
 142                 if ( $this->cliMode ) {
 143                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 144                 }
 145
 146                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 147                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 148                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 149                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 150                 if ( $this->getServerVersion() >= 9.0 ) {
 151                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 152                 }
 153
 154                 $this->determineCoreSchema( $this->mSchema );
 155
 156                 return $this->mConn;
 157         }
 158
 159         /**
 160          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 161          * DB name doesn't match the open connection, open a new one
 162          * @param string $db
 163          * @return bool
 164          */
 165         function selectDB( $db ) {
 166                 if ( $this->mDBname !== $db ) {
 167                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 168                 } else {
 169                         return true;
 170                 }
 171         }
 172
 173         function makeConnectionString( $vars ) {
 174                 $s = '';
 175                 foreach ( $vars as $name => $value ) {
 176                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 177                 }
 178
 179                 return $s;
 180         }
 181
 182         /**
 183          * Closes a database connection, if it is open
 184          * Returns success, true if already closed
 185          * @return bool
 186          */
 187         protected function closeConnection() {
 188                 return $this->mConn ? pg_close( $this->mConn ) : true;
 189         }
 190
 191         public function doQuery( $sql ) {
 192                 $conn = $this->getBindingHandle();
 193
 194                 $sql = mb_convert_encoding( $sql, 'UTF-8' );
 195                 // Clear previously left over PQresult
 196                 while ( $res = pg_get_result( $conn ) ) {
 197                         pg_free_result( $res );
 198                 }
 199                 if ( pg_send_query( $conn, $sql ) === false ) {
 200                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 201                 }
 202                 $this->mLastResult = pg_get_result( $conn );
 203                 $this->mAffectedRows = null;
 204                 if ( pg_result_error( $this->mLastResult ) ) {
 205                         return false;
 206                 }
 207
 208                 return $this->mLastResult;
 209         }
 210
 211         protected function dumpError() {
 212                 $diags = [
 213                         PGSQL_DIAG_SEVERITY,
 214                         PGSQL_DIAG_SQLSTATE,
 215                         PGSQL_DIAG_MESSAGE_PRIMARY,
 216                         PGSQL_DIAG_MESSAGE_DETAIL,
 217                         PGSQL_DIAG_MESSAGE_HINT,
 218                         PGSQL_DIAG_STATEMENT_POSITION,
 219                         PGSQL_DIAG_INTERNAL_POSITION,
 220                         PGSQL_DIAG_INTERNAL_QUERY,
 221                         PGSQL_DIAG_CONTEXT,
 222                         PGSQL_DIAG_SOURCE_FILE,
 223                         PGSQL_DIAG_SOURCE_LINE,
 224                         PGSQL_DIAG_SOURCE_FUNCTION
 225                 ];
 226                 foreach ( $diags as $d ) {
 227                         $this->queryLogger->debug( sprintf( "PgSQL ERROR(%d): %s\n",
 228                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 229                 }
 230         }
 231
 232         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 233                 if ( $tempIgnore ) {
 234                         /* Check for constraint violation */
 235                         if ( $errno === '23505' ) {
 236                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 237
 238                                 return;
 239                         }
 240                 }
 241                 /* Transaction stays in the ERROR state until rolled back */
 242                 if ( $this->mTrxLevel ) {
 243                         $ignore = $this->ignoreErrors( true );
 244                         $this->rollback( __METHOD__ );
 245                         $this->ignoreErrors( $ignore );
 246                 }
 247                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 248         }
 249
 250         function queryIgnore( $sql, $fname = __METHOD__ ) {
 251                 return $this->query( $sql, $fname, true );
 252         }
 253
 254         /**
 255          * @param stdClass|ResultWrapper $res
 256          * @throws DBUnexpectedError
 257          */
 258         function freeResult( $res ) {
 259                 if ( $res instanceof ResultWrapper ) {
 260                         $res = $res->result;
 261                 }
 262                 MediaWiki\suppressWarnings();
 263                 $ok = pg_free_result( $res );
 264                 MediaWiki\restoreWarnings();
 265                 if ( !$ok ) {
 266                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 267                 }
 268         }
 269
 270         /**
 271          * @param ResultWrapper|stdClass $res
 272          * @return stdClass
 273          * @throws DBUnexpectedError
 274          */
 275         function fetchObject( $res ) {
 276                 if ( $res instanceof ResultWrapper ) {
 277                         $res = $res->result;
 278                 }
 279                 MediaWiki\suppressWarnings();
 280                 $row = pg_fetch_object( $res );
 281                 MediaWiki\restoreWarnings();
 282                 # @todo FIXME: HACK HACK HACK HACK debug
 283
 284                 # @todo hashar: not sure if the following test really trigger if the object
 285                 #          fetching failed.
 286                 $conn = $this->getBindingHandle();
 287                 if ( pg_last_error( $conn ) ) {
 288                         throw new DBUnexpectedError(
 289                                 $this,
 290                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 291                         );
 292                 }
 293
 294                 return $row;
 295         }
 296
 297         function fetchRow( $res ) {
 298                 if ( $res instanceof ResultWrapper ) {
 299                         $res = $res->result;
 300                 }
 301                 MediaWiki\suppressWarnings();
 302                 $row = pg_fetch_array( $res );
 303                 MediaWiki\restoreWarnings();
 304
 305                 $conn = $this->getBindingHandle();
 306                 if ( pg_last_error( $conn ) ) {
 307                         throw new DBUnexpectedError(
 308                                 $this,
 309                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 310                         );
 311                 }
 312
 313                 return $row;
 314         }
 315
 316         function numRows( $res ) {
 317                 if ( $res instanceof ResultWrapper ) {
 318                         $res = $res->result;
 319                 }
 320                 MediaWiki\suppressWarnings();
 321                 $n = pg_num_rows( $res );
 322                 MediaWiki\restoreWarnings();
 323
 324                 $conn = $this->getBindingHandle();
 325                 if ( pg_last_error( $conn ) ) {
 326                         throw new DBUnexpectedError(
 327                                 $this,
 328                                 'SQL error: ' . htmlspecialchars( pg_last_error( $conn ) )
 329                         );
 330                 }
 331
 332                 return $n;
 333         }
 334
 335         function numFields( $res ) {
 336                 if ( $res instanceof ResultWrapper ) {
 337                         $res = $res->result;
 338                 }
 339
 340                 return pg_num_fields( $res );
 341         }
 342
 343         function fieldName( $res, $n ) {
 344                 if ( $res instanceof ResultWrapper ) {
 345                         $res = $res->result;
 346                 }
 347
 348                 return pg_field_name( $res, $n );
 349         }
 350
 351         /**
 352          * Return the result of the last call to nextSequenceValue();
 353          * This must be called after nextSequenceValue().
 354          *
 355          * @return int|null
 356          */
 357         function insertId() {
 358                 return $this->mInsertId;
 359         }
 360
 361         /**
 362          * @param mixed $res
 363          * @param int $row
 364          * @return bool
 365          */
 366         function dataSeek( $res, $row ) {
 367                 if ( $res instanceof ResultWrapper ) {
 368                         $res = $res->result;
 369                 }
 370
 371                 return pg_result_seek( $res, $row );
 372         }
 373
 374         function lastError() {
 375                 if ( $this->mConn ) {
 376                         if ( $this->mLastResult ) {
 377                                 return pg_result_error( $this->mLastResult );
 378                         } else {
 379                                 return pg_last_error();
 380                         }
 381                 }
 382
 383                 return $this->getLastPHPError() ?: 'No database connection';
 384         }
 385
 386         function lastErrno() {
 387                 if ( $this->mLastResult ) {
 388                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 389                 } else {
 390                         return false;
 391                 }
 392         }
 393
 394         function affectedRows() {
 395                 if ( !is_null( $this->mAffectedRows ) ) {
 396                         // Forced result for simulated queries
 397                         return $this->mAffectedRows;
 398                 }
 399                 if ( empty( $this->mLastResult ) ) {
 400                         return 0;
 401                 }
 402
 403                 return pg_affected_rows( $this->mLastResult );
 404         }
 405
 406         /**
 407          * Estimate rows in dataset
 408          * Returns estimated count, based on EXPLAIN output
 409          * This is not necessarily an accurate estimate, so use sparingly
 410          * Returns -1 if count cannot be found
 411          * Takes same arguments as Database::select()
 412          *
 413          * @param string $table
 414          * @param string $vars
 415          * @param string $conds
 416          * @param string $fname
 417          * @param array $options
 418          * @return int
 419          */
 420         function estimateRowCount( $table, $vars = '*', $conds = '',
 421                 $fname = __METHOD__, $options = []
 422         ) {
 423                 $options['EXPLAIN'] = true;
 424                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 425                 $rows = -1;
 426                 if ( $res ) {
 427                         $row = $this->fetchRow( $res );
 428                         $count = [];
 429                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 430                                 $rows = (int)$count[1];
 431                         }
 432                 }
 433
 434                 return $rows;
 435         }
 436
 437         /**
 438          * Returns information about an index
 439          * If errors are explicitly ignored, returns NULL on failure
 440          *
 441          * @param string $table
 442          * @param string $index
 443          * @param string $fname
 444          * @return bool|null
 445          */
 446         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 447                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 448                 $res = $this->query( $sql, $fname );
 449                 if ( !$res ) {
 450                         return null;
 451                 }
 452                 foreach ( $res as $row ) {
 453                         if ( $row->indexname == $this->indexName( $index ) ) {
 454                                 return $row;
 455                         }
 456                 }
 457
 458                 return false;
 459         }
 460
 461         /**
 462          * Returns is of attributes used in index
 463          *
 464          * @since 1.19
 465          * @param string $index
 466          * @param bool|string $schema
 467          * @return array
 468          */
 469         function indexAttributes( $index, $schema = false ) {
 470                 if ( $schema === false ) {
 471                         $schema = $this->getCoreSchema();
 472                 }
 473                 /*
 474                  * A subquery would be not needed if we didn't care about the order
 475                  * of attributes, but we do
 476                  */
 477                 $sql = <<<__INDEXATTR__
 478
 479                         SELECT opcname,
 480                                 attname,
 481                                 i.indoption[s.g] as option,
 482                                 pg_am.amname
 483                         FROM
 484                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 485                                         FROM
 486                                                 pg_index isub
 487                                         JOIN pg_class cis
 488                                                 ON cis.oid=isub.indexrelid
 489                                         JOIN pg_namespace ns
 490                                                 ON cis.relnamespace = ns.oid
 491                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 492                                 pg_attribute,
 493                                 pg_opclass opcls,
 494                                 pg_am,
 495                                 pg_class ci
 496                                 JOIN pg_index i
 497                                         ON ci.oid=i.indexrelid
 498                                 JOIN pg_class ct
 499                                         ON ct.oid = i.indrelid
 500                                 JOIN pg_namespace n
 501                                         ON ci.relnamespace = n.oid
 502                                 WHERE
 503                                         ci.relname='$index' AND n.nspname='$schema'
 504                                         AND     attrelid = ct.oid
 505                                         AND     i.indkey[s.g] = attnum
 506                                         AND     i.indclass[s.g] = opcls.oid
 507                                         AND     pg_am.oid = opcls.opcmethod
 508 __INDEXATTR__;
 509                 $res = $this->query( $sql, __METHOD__ );
 510                 $a = [];
 511                 if ( $res ) {
 512                         foreach ( $res as $row ) {
 513                                 $a[] = [
 514                                         $row->attname,
 515                                         $row->opcname,
 516                                         $row->amname,
 517                                         $row->option ];
 518                         }
 519                 } else {
 520                         return null;
 521                 }
 522
 523                 return $a;
 524         }
 525
 526         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 527                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 528                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 529                         $this->strencode( $this->indexName( $index ) ) .
 530                         ")'";
 531                 $res = $this->query( $sql, $fname );
 532                 if ( !$res ) {
 533                         return null;
 534                 }
 535
 536                 return $res->numRows() > 0;
 537         }
 538
 539         function selectSQLText(
 540                 $table, $vars, $conds = '', $fname = __METHOD__, $options = [], $join_conds = []
 541         ) {
 542                 // Change the FOR UPDATE option as necessary based on the join conditions. Then pass
 543                 // to the parent function to get the actual SQL text.
 544                 // In Postgres when using FOR UPDATE, only the main table and tables that are inner joined
 545                 // can be locked. That means tables in an outer join cannot be FOR UPDATE locked. Trying to
 546                 // do so causes a DB error. This wrapper checks which tables can be locked and adjusts it
 547                 // accordingly.
 548                 // MySQL uses "ORDER BY NULL" as an optimization hint, but that is illegal in PostgreSQL.
 549                 if ( is_array( $options ) ) {
 550                         $forUpdateKey = array_search( 'FOR UPDATE', $options, true );
 551                         if ( $forUpdateKey !== false && $join_conds ) {
 552                                 unset( $options[$forUpdateKey] );
 553
 554                                 foreach ( $join_conds as $table_cond => $join_cond ) {
 555                                         if ( 0 === preg_match( '/^(?:LEFT|RIGHT|FULL)(?: OUTER)? JOIN$/i', $join_cond[0] ) ) {
 556                                                 $options['FOR UPDATE'][] = $table_cond;
 557                                         }
 558                                 }
 559                         }
 560
 561                         if ( isset( $options['ORDER BY'] ) && $options['ORDER BY'] == 'NULL' ) {
 562                                 unset( $options['ORDER BY'] );
 563                         }
 564                 }
 565
 566                 return parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 567         }
 568
 569         /**
 570          * INSERT wrapper, inserts an array into a table
 571          *
 572          * $args may be a single associative array, or an array of these with numeric keys,
 573          * for multi-row insert (Postgres version 8.2 and above only).
 574          *
 575          * @param string $table Name of the table to insert to.
 576          * @param array $args Items to insert into the table.
 577          * @param string $fname Name of the function, for profiling
 578          * @param array|string $options String or array. Valid options: IGNORE
 579          * @return bool Success of insert operation. IGNORE always returns true.
 580          */
 581         function insert( $table, $args, $fname = __METHOD__, $options = [] ) {
 582                 if ( !count( $args ) ) {
 583                         return true;
 584                 }
 585
 586                 $table = $this->tableName( $table );
 587                 if ( !isset( $this->numericVersion ) ) {
 588                         $this->getServerVersion();
 589                 }
 590
 591                 if ( !is_array( $options ) ) {
 592                         $options = [ $options ];
 593                 }
 594
 595                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 596                         $multi = true;
 597                         $keys = array_keys( $args[0] );
 598                 } else {
 599                         $multi = false;
 600                         $keys = array_keys( $args );
 601                 }
 602
 603                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 604                 $savepoint = $olde = null;
 605                 $numrowsinserted = 0;
 606                 if ( in_array( 'IGNORE', $options ) ) {
 607                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 608                         $olde = error_reporting( 0 );
 609                         // For future use, we may want to track the number of actual inserts
 610                         // Right now, insert (all writes) simply return true/false
 611                 }
 612
 613                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 614
 615                 if ( $multi ) {
 616                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 617                                 $first = true;
 618                                 foreach ( $args as $row ) {
 619                                         if ( $first ) {
 620                                                 $first = false;
 621                                         } else {
 622                                                 $sql .= ',';
 623                                         }
 624                                         $sql .= '(' . $this->makeList( $row ) . ')';
 625                                 }
 626                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 627                         } else {
 628                                 $res = true;
 629                                 $origsql = $sql;
 630                                 foreach ( $args as $row ) {
 631                                         $tempsql = $origsql;
 632                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 633
 634                                         if ( $savepoint ) {
 635                                                 $savepoint->savepoint();
 636                                         }
 637
 638                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 639
 640                                         if ( $savepoint ) {
 641                                                 $bar = pg_result_error( $this->mLastResult );
 642                                                 if ( $bar != false ) {
 643                                                         $savepoint->rollback();
 644                                                 } else {
 645                                                         $savepoint->release();
 646                                                         $numrowsinserted++;
 647                                                 }
 648                                         }
 649
 650                                         // If any of them fail, we fail overall for this function call
 651                                         // Note that this will be ignored if IGNORE is set
 652                                         if ( !$tempres ) {
 653                                                 $res = false;
 654                                         }
 655                                 }
 656                         }
 657                 } else {
 658                         // Not multi, just a lone insert
 659                         if ( $savepoint ) {
 660                                 $savepoint->savepoint();
 661                         }
 662
 663                         $sql .= '(' . $this->makeList( $args ) . ')';
 664                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 665                         if ( $savepoint ) {
 666                                 $bar = pg_result_error( $this->mLastResult );
 667                                 if ( $bar != false ) {
 668                                         $savepoint->rollback();
 669                                 } else {
 670                                         $savepoint->release();
 671                                         $numrowsinserted++;
 672                                 }
 673                         }
 674                 }
 675                 if ( $savepoint ) {
 676                         error_reporting( $olde );
 677                         $savepoint->commit();
 678
 679                         // Set the affected row count for the whole operation
 680                         $this->mAffectedRows = $numrowsinserted;
 681
 682                         // IGNORE always returns true
 683                         return true;
 684                 }
 685
 686                 return $res;
 687         }
 688
 689         /**
 690          * INSERT SELECT wrapper
 691          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 692          * Source items may be literals rather then field names, but strings should
 693          * be quoted with Database::addQuotes()
 694          * $conds may be "*" to copy the whole table
 695          * srcTable may be an array of tables.
 696          * @todo FIXME: Implement this a little better (seperate select/insert)?
 697          *
 698          * @param string $destTable
 699          * @param array|string $srcTable
 700          * @param array $varMap
 701          * @param array $conds
 702          * @param string $fname
 703          * @param array $insertOptions
 704          * @param array $selectOptions
 705          * @return bool
 706          */
 707         function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 708                 $insertOptions = [], $selectOptions = [] ) {
 709                 $destTable = $this->tableName( $destTable );
 710
 711                 if ( !is_array( $insertOptions ) ) {
 712                         $insertOptions = [ $insertOptions ];
 713                 }
 714
 715                 /*
 716                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 717                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 718                  */
 719                 $savepoint = $olde = null;
 720                 $numrowsinserted = 0;
 721                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 722                         $savepoint = new SavepointPostgres( $this, 'mw', $this->queryLogger );
 723                         $olde = error_reporting( 0 );
 724                         $savepoint->savepoint();
 725                 }
 726
 727                 if ( !is_array( $selectOptions ) ) {
 728                         $selectOptions = [ $selectOptions ];
 729                 }
 730                 list( $startOpts, $useIndex, $tailOpts, $ignoreIndex ) =
 731                         $this->makeSelectOptions( $selectOptions );
 732                 if ( is_array( $srcTable ) ) {
 733                         $srcTable = implode( ',', array_map( [ &$this, 'tableName' ], $srcTable ) );
 734                 } else {
 735                         $srcTable = $this->tableName( $srcTable );
 736                 }
 737
 738                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 739                         " SELECT $startOpts " . implode( ',', $varMap ) .
 740                         " FROM $srcTable $useIndex $ignoreIndex ";
 741
 742                 if ( $conds != '*' ) {
 743                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 744                 }
 745
 746                 $sql .= " $tailOpts";
 747
 748                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 749                 if ( $savepoint ) {
 750                         $bar = pg_result_error( $this->mLastResult );
 751                         if ( $bar != false ) {
 752                                 $savepoint->rollback();
 753                         } else {
 754                                 $savepoint->release();
 755                                 $numrowsinserted++;
 756                         }
 757                         error_reporting( $olde );
 758                         $savepoint->commit();
 759
 760                         // Set the affected row count for the whole operation
 761                         $this->mAffectedRows = $numrowsinserted;
 762
 763                         // IGNORE always returns true
 764                         return true;
 765                 }
 766
 767                 return $res;
 768         }
 769
 770         function tableName( $name, $format = 'quoted' ) {
 771                 # Replace reserved words with better ones
 772                 switch ( $name ) {
 773                         case 'user':
 774                                 return $this->realTableName( 'mwuser', $format );
 775                         case 'text':
 776                                 return $this->realTableName( 'pagecontent', $format );
 777                         default:
 778                                 return $this->realTableName( $name, $format );
 779                 }
 780         }
 781
 782         /* Don't cheat on installer */
 783         function realTableName( $name, $format = 'quoted' ) {
 784                 return parent::tableName( $name, $format );
 785         }
 786
 787         /**
 788          * Return the next in a sequence, save the value for retrieval via insertId()
 789          *
 790          * @param string $seqName
 791          * @return int|null
 792          */
 793         function nextSequenceValue( $seqName ) {
 794                 $safeseq = str_replace( "'", "''", $seqName );
 795                 $res = $this->query( "SELECT nextval('$safeseq')" );
 796                 $row = $this->fetchRow( $res );
 797                 $this->mInsertId = $row[0];
 798
 799                 return $this->mInsertId;
 800         }
 801
 802         /**
 803          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
 804          *
 805          * @param string $seqName
 806          * @return int
 807          */
 808         function currentSequenceValue( $seqName ) {
 809                 $safeseq = str_replace( "'", "''", $seqName );
 810                 $res = $this->query( "SELECT currval('$safeseq')" );
 811                 $row = $this->fetchRow( $res );
 812                 $currval = $row[0];
 813
 814                 return $currval;
 815         }
 816
 817         # Returns the size of a text field, or -1 for "unlimited"
 818         function textFieldSize( $table, $field ) {
 819                 $table = $this->tableName( $table );
 820                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
 821                         FROM pg_class c, pg_attribute a, pg_type t
 822                         WHERE relname='$table' AND a.attrelid=c.oid AND
 823                                 a.atttypid=t.oid and a.attname='$field'";
 824                 $res = $this->query( $sql );
 825                 $row = $this->fetchObject( $res );
 826                 if ( $row->ftype == 'varchar' ) {
 827                         $size = $row->size - 4;
 828                 } else {
 829                         $size = $row->size;
 830                 }
 831
 832                 return $size;
 833         }
 834
 835         function limitResult( $sql, $limit, $offset = false ) {
 836                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
 837         }
 838
 839         function wasDeadlock() {
 840                 return $this->lastErrno() == '40P01';
 841         }
 842
 843         function duplicateTableStructure(
 844                 $oldName, $newName, $temporary = false, $fname = __METHOD__
 845         ) {
 846                 $newName = $this->addIdentifierQuotes( $newName );
 847                 $oldName = $this->addIdentifierQuotes( $oldName );
 848
 849                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
 850                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
 851         }
 852
 853         function listTables( $prefix = null, $fname = __METHOD__ ) {
 854                 $eschema = $this->addQuotes( $this->getCoreSchema() );
 855                 $result = $this->query(
 856                         "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
 857                 $endArray = [];
 858
 859                 foreach ( $result as $table ) {
 860                         $vars = get_object_vars( $table );
 861                         $table = array_pop( $vars );
 862                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
 863                                 $endArray[] = $table;
 864                         }
 865                 }
 866
 867                 return $endArray;
 868         }
 869
 870         function timestamp( $ts = 0 ) {
 871                 $ct = new ConvertibleTimestamp( $ts );
 872
 873                 return $ct->getTimestamp( TS_POSTGRES );
 874         }
 875
 876         /**
 877          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
 878          * to http://www.php.net/manual/en/ref.pgsql.php
 879          *
 880          * Parsing a postgres array can be a tricky problem, he's my
 881          * take on this, it handles multi-dimensional arrays plus
 882          * escaping using a nasty regexp to determine the limits of each
 883          * data-item.
 884          *
 885          * This should really be handled by PHP PostgreSQL module
 886          *
 887          * @since 1.19
 888          * @param string $text Postgreql array returned in a text form like {a,b}
 889          * @param string $output
 890          * @param int|bool $limit
 891          * @param int $offset
 892          * @return string
 893          */
 894         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
 895                 if ( false === $limit ) {
 896                         $limit = strlen( $text ) - 1;
 897                         $output = [];
 898                 }
 899                 if ( '{}' == $text ) {
 900                         return $output;
 901                 }
 902                 do {
 903                         if ( '{' != $text[$offset] ) {
 904                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
 905                                         $text, $match, 0, $offset );
 906                                 $offset += strlen( $match[0] );
 907                                 $output[] = ( '"' != $match[1][0]
 908                                         ? $match[1]
 909                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
 910                                 if ( '},' == $match[3] ) {
 911                                         return $output;
 912                                 }
 913                         } else {
 914                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
 915                         }
 916                 } while ( $limit > $offset );
 917
 918                 return $output;
 919         }
 920
 921         /**
 922          * Return aggregated value function call
 923          * @param array $valuedata
 924          * @param string $valuename
 925          * @return array
 926          */
 927         public function aggregateValue( $valuedata, $valuename = 'value' ) {
 928                 return $valuedata;
 929         }
 930
 931         /**
 932          * @return string Wikitext of a link to the server software's web site
 933          */
 934         public function getSoftwareLink() {
 935                 return '[{{int:version-db-postgres-url}} PostgreSQL]';
 936         }
 937
 938         /**
 939          * Return current schema (executes SELECT current_schema())
 940          * Needs transaction
 941          *
 942          * @since 1.19
 943          * @return string Default schema for the current session
 944          */
 945         function getCurrentSchema() {
 946                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
 947                 $row = $this->fetchRow( $res );
 948
 949                 return $row[0];
 950         }
 951
 952         /**
 953          * Return list of schemas which are accessible without schema name
 954          * This is list does not contain magic keywords like "$user"
 955          * Needs transaction
 956          *
 957          * @see getSearchPath()
 958          * @see setSearchPath()
 959          * @since 1.19
 960          * @return array List of actual schemas for the current sesson
 961          */
 962         function getSchemas() {
 963                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
 964                 $row = $this->fetchRow( $res );
 965                 $schemas = [];
 966
 967                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
 968
 969                 return $this->pg_array_parse( $row[0], $schemas );
 970         }
 971
 972         /**
 973          * Return search patch for schemas
 974          * This is different from getSchemas() since it contain magic keywords
 975          * (like "$user").
 976          * Needs transaction
 977          *
 978          * @since 1.19
 979          * @return array How to search for table names schemas for the current user
 980          */
 981         function getSearchPath() {
 982                 $res = $this->query( "SHOW search_path", __METHOD__ );
 983                 $row = $this->fetchRow( $res );
 984
 985                 /* PostgreSQL returns SHOW values as strings */
 986
 987                 return explode( ",", $row[0] );
 988         }
 989
 990         /**
 991          * Update search_path, values should already be sanitized
 992          * Values may contain magic keywords like "$user"
 993          * @since 1.19
 994          *
 995          * @param array $search_path List of schemas to be searched by default
 996          */
 997         function setSearchPath( $search_path ) {
 998                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
 999         }
1000
1001         /**
1002          * Determine default schema for the current application
1003          * Adjust this session schema search path if desired schema exists
1004          * and is not alread there.
1005          *
1006          * We need to have name of the core schema stored to be able
1007          * to query database metadata.
1008          *
1009          * This will be also called by the installer after the schema is created
1010          *
1011          * @since 1.19
1012          *
1013          * @param string $desiredSchema
1014          */
1015         function determineCoreSchema( $desiredSchema ) {
1016                 $this->begin( __METHOD__, self::TRANSACTION_INTERNAL );
1017                 if ( $this->schemaExists( $desiredSchema ) ) {
1018                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1019                                 $this->mCoreSchema = $desiredSchema;
1020                                 $this->queryLogger->debug(
1021                                         "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1022                         } else {
1023                                 /**
1024                                  * Prepend our schema (e.g. 'mediawiki') in front
1025                                  * of the search path
1026                                  * Fixes bug 15816
1027                                  */
1028                                 $search_path = $this->getSearchPath();
1029                                 array_unshift( $search_path,
1030                                         $this->addIdentifierQuotes( $desiredSchema ) );
1031                                 $this->setSearchPath( $search_path );
1032                                 $this->mCoreSchema = $desiredSchema;
1033                                 $this->queryLogger->debug(
1034                                         "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1035                         }
1036                 } else {
1037                         $this->mCoreSchema = $this->getCurrentSchema();
1038                         $this->queryLogger->debug(
1039                                 "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1040                                 $this->mCoreSchema . "\"\n" );
1041                 }
1042                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1043                 $this->commit( __METHOD__, self::FLUSHING_INTERNAL );
1044         }
1045
1046         /**
1047          * Return schema name for core application tables
1048          *
1049          * @since 1.19
1050          * @return string Core schema name
1051          */
1052         function getCoreSchema() {
1053                 return $this->mCoreSchema;
1054         }
1055
1056         /**
1057          * @return string Version information from the database
1058          */
1059         function getServerVersion() {
1060                 if ( !isset( $this->numericVersion ) ) {
1061                         $conn = $this->getBindingHandle();
1062                         $versionInfo = pg_version( $conn );
1063                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1064                                 // Old client, abort install
1065                                 $this->numericVersion = '7.3 or earlier';
1066                         } elseif ( isset( $versionInfo['server'] ) ) {
1067                                 // Normal client
1068                                 $this->numericVersion = $versionInfo['server'];
1069                         } else {
1070                                 // Bug 16937: broken pgsql extension from PHP<5.3
1071                                 $this->numericVersion = pg_parameter_status( $conn, 'server_version' );
1072                         }
1073                 }
1074
1075                 return $this->numericVersion;
1076         }
1077
1078         /**
1079          * Query whether a given relation exists (in the given schema, or the
1080          * default mw one if not given)
1081          * @param string $table
1082          * @param array|string $types
1083          * @param bool|string $schema
1084          * @return bool
1085          */
1086         function relationExists( $table, $types, $schema = false ) {
1087                 if ( !is_array( $types ) ) {
1088                         $types = [ $types ];
1089                 }
1090                 if ( $schema === false ) {
1091                         $schema = $this->getCoreSchema();
1092                 }
1093                 $table = $this->realTableName( $table, 'raw' );
1094                 $etable = $this->addQuotes( $table );
1095                 $eschema = $this->addQuotes( $schema );
1096                 $sql = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1097                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1098                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1099                 $res = $this->query( $sql );
1100                 $count = $res ? $res->numRows() : 0;
1101
1102                 return (bool)$count;
1103         }
1104
1105         /**
1106          * For backward compatibility, this function checks both tables and
1107          * views.
1108          * @param string $table
1109          * @param string $fname
1110          * @param bool|string $schema
1111          * @return bool
1112          */
1113         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1114                 return $this->relationExists( $table, [ 'r', 'v' ], $schema );
1115         }
1116
1117         function sequenceExists( $sequence, $schema = false ) {
1118                 return $this->relationExists( $sequence, 'S', $schema );
1119         }
1120
1121         function triggerExists( $table, $trigger ) {
1122                 $q = <<<SQL
1123         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1124                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1125                           AND tgrelid=pg_class.oid
1126                           AND nspname=%s AND relname=%s AND tgname=%s
1127 SQL;
1128                 $res = $this->query(
1129                         sprintf(
1130                                 $q,
1131                                 $this->addQuotes( $this->getCoreSchema() ),
1132                                 $this->addQuotes( $table ),
1133                                 $this->addQuotes( $trigger )
1134                         )
1135                 );
1136                 if ( !$res ) {
1137                         return null;
1138                 }
1139                 $rows = $res->numRows();
1140
1141                 return $rows;
1142         }
1143
1144         function ruleExists( $table, $rule ) {
1145                 $exists = $this->selectField( 'pg_rules', 'rulename',
1146                         [
1147                                 'rulename' => $rule,
1148                                 'tablename' => $table,
1149                                 'schemaname' => $this->getCoreSchema()
1150                         ]
1151                 );
1152
1153                 return $exists === $rule;
1154         }
1155
1156         function constraintExists( $table, $constraint ) {
1157                 $sql = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1158                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1159                         $this->addQuotes( $this->getCoreSchema() ),
1160                         $this->addQuotes( $table ),
1161                         $this->addQuotes( $constraint )
1162                 );
1163                 $res = $this->query( $sql );
1164                 if ( !$res ) {
1165                         return null;
1166                 }
1167                 $rows = $res->numRows();
1168
1169                 return $rows;
1170         }
1171
1172         /**
1173          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1174          * @param string $schema
1175          * @return bool
1176          */
1177         function schemaExists( $schema ) {
1178                 $exists = $this->selectField( '"pg_catalog"."pg_namespace"', 1,
1179                         [ 'nspname' => $schema ], __METHOD__ );
1180
1181                 return (bool)$exists;
1182         }
1183
1184         /**
1185          * Returns true if a given role (i.e. user) exists, false otherwise.
1186          * @param string $roleName
1187          * @return bool
1188          */
1189         function roleExists( $roleName ) {
1190                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1191                         [ 'rolname' => $roleName ], __METHOD__ );
1192
1193                 return (bool)$exists;
1194         }
1195
1196         /**
1197          * @var string $table
1198          * @var string $field
1199          * @return PostgresField|null
1200          */
1201         function fieldInfo( $table, $field ) {
1202                 return PostgresField::fromText( $this, $table, $field );
1203         }
1204
1205         /**
1206          * pg_field_type() wrapper
1207          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1208          * @param int $index Field number, starting from 0
1209          * @return string
1210          */
1211         function fieldType( $res, $index ) {
1212                 if ( $res instanceof ResultWrapper ) {
1213                         $res = $res->result;
1214                 }
1215
1216                 return pg_field_type( $res, $index );
1217         }
1218
1219         /**
1220          * @param string $b
1221          * @return Blob
1222          */
1223         function encodeBlob( $b ) {
1224                 return new PostgresBlob( pg_escape_bytea( $b ) );
1225         }
1226
1227         function decodeBlob( $b ) {
1228                 if ( $b instanceof PostgresBlob ) {
1229                         $b = $b->fetch();
1230                 } elseif ( $b instanceof Blob ) {
1231                         return $b->fetch();
1232                 }
1233
1234                 return pg_unescape_bytea( $b );
1235         }
1236
1237         function strencode( $s ) {
1238                 // Should not be called by us
1239                 return pg_escape_string( $this->getBindingHandle(), $s );
1240         }
1241
1242         /**
1243          * @param string|int|null|bool|Blob $s
1244          * @return string|int
1245          */
1246         function addQuotes( $s ) {
1247                 $conn = $this->getBindingHandle();
1248
1249                 if ( is_null( $s ) ) {
1250                         return 'NULL';
1251                 } elseif ( is_bool( $s ) ) {
1252                         return intval( $s );
1253                 } elseif ( $s instanceof Blob ) {
1254                         if ( $s instanceof PostgresBlob ) {
1255                                 $s = $s->fetch();
1256                         } else {
1257                                 $s = pg_escape_bytea( $conn, $s->fetch() );
1258                         }
1259                         return "'$s'";
1260                 }
1261
1262                 return "'" . pg_escape_string( $conn, $s ) . "'";
1263         }
1264
1265         /**
1266          * Postgres specific version of replaceVars.
1267          * Calls the parent version in Database.php
1268          *
1269          * @param string $ins SQL string, read from a stream (usually tables.sql)
1270          * @return string SQL string
1271          */
1272         protected function replaceVars( $ins ) {
1273                 $ins = parent::replaceVars( $ins );
1274
1275                 if ( $this->numericVersion >= 8.3 ) {
1276                         // Thanks for not providing backwards-compatibility, 8.3
1277                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1278                 }
1279
1280                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1281                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1282                 }
1283
1284                 return $ins;
1285         }
1286
1287         /**
1288          * Various select options
1289          *
1290          * @param array $options An associative array of options to be turned into
1291          *   an SQL query, valid keys are listed in the function.
1292          * @return array
1293          */
1294         function makeSelectOptions( $options ) {
1295                 $preLimitTail = $postLimitTail = '';
1296                 $startOpts = $useIndex = $ignoreIndex = '';
1297
1298                 $noKeyOptions = [];
1299                 foreach ( $options as $key => $option ) {
1300                         if ( is_numeric( $key ) ) {
1301                                 $noKeyOptions[$option] = true;
1302                         }
1303                 }
1304
1305                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1306
1307                 $preLimitTail .= $this->makeOrderBy( $options );
1308
1309                 // if ( isset( $options['LIMIT'] ) ) {
1310                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1311                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1312                 //              : false );
1313                 // }
1314
1315                 if ( isset( $options['FOR UPDATE'] ) ) {
1316                         $postLimitTail .= ' FOR UPDATE OF ' .
1317                                 implode( ', ', array_map( [ &$this, 'tableName' ], $options['FOR UPDATE'] ) );
1318                 } elseif ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1319                         $postLimitTail .= ' FOR UPDATE';
1320                 }
1321
1322                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1323                         $startOpts .= 'DISTINCT';
1324                 }
1325
1326                 return [ $startOpts, $useIndex, $preLimitTail, $postLimitTail, $ignoreIndex ];
1327         }
1328
1329         function getDBname() {
1330                 return $this->mDBname;
1331         }
1332
1333         function getServer() {
1334                 return $this->mServer;
1335         }
1336
1337         function buildConcat( $stringList ) {
1338                 return implode( ' || ', $stringList );
1339         }
1340
1341         public function buildGroupConcatField(
1342                 $delimiter, $table, $field, $conds = '', $options = [], $join_conds = []
1343         ) {
1344                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1345
1346                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, [], $join_conds ) . ')';
1347         }
1348
1349         /**
1350          * @param string $field Field or column to cast
1351          * @return string
1352          * @since 1.28
1353          */
1354         public function buildStringCast( $field ) {
1355                 return $field . '::text';
1356         }
1357
1358         public function streamStatementEnd( &$sql, &$newLine ) {
1359                 # Allow dollar quoting for function declarations
1360                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1361                         if ( $this->delimiter ) {
1362                                 $this->delimiter = false;
1363                         } else {
1364                                 $this->delimiter = ';';
1365                         }
1366                 }
1367
1368                 return parent::streamStatementEnd( $sql, $newLine );
1369         }
1370
1371         /**
1372          * Check to see if a named lock is available. This is non-blocking.
1373          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1374          *
1375          * @param string $lockName Name of lock to poll
1376          * @param string $method Name of method calling us
1377          * @return bool
1378          * @since 1.20
1379          */
1380         public function lockIsFree( $lockName, $method ) {
1381                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1382                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1383                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1384                 $row = $this->fetchObject( $result );
1385
1386                 return ( $row->lockstatus === 't' );
1387         }
1388
1389         /**
1390          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1391          * @param string $lockName
1392          * @param string $method
1393          * @param int $timeout
1394          * @return bool
1395          */
1396         public function lock( $lockName, $method, $timeout = 5 ) {
1397                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1398                 $loop = new WaitConditionLoop(
1399                         function () use ( $lockName, $key, $timeout, $method ) {
1400                                 $res = $this->query( "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1401                                 $row = $this->fetchObject( $res );
1402                                 if ( $row->lockstatus === 't' ) {
1403                                         parent::lock( $lockName, $method, $timeout ); // record
1404                                         return true;
1405                                 }
1406
1407                                 return WaitConditionLoop::CONDITION_CONTINUE;
1408                         },
1409                         $timeout
1410                 );
1411
1412                 return ( $loop->invoke() === $loop::CONDITION_REACHED );
1413         }
1414
1415         /**
1416          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1417          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1418          * @param string $lockName
1419          * @param string $method
1420          * @return bool
1421          */
1422         public function unlock( $lockName, $method ) {
1423                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1424                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1425                 $row = $this->fetchObject( $result );
1426
1427                 if ( $row->lockstatus === 't' ) {
1428                         parent::unlock( $lockName, $method ); // record
1429                         return true;
1430                 }
1431
1432                 $this->queryLogger->debug( __METHOD__ . " failed to release lock\n" );
1433
1434                 return false;
1435         }
1436
1437         /**
1438          * @param string $lockName
1439          * @return string Integer
1440          */
1441         private function bigintFromLockName( $lockName ) {
1442                 return Wikimedia\base_convert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1443         }
1444 }