includes/db/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
  24 class PostgresField implements Field {
  25         private $name, $tablename, $type, $nullable, $max_length, $deferred, $deferrable, $conname,
  26                 $has_default, $default;
  27
  28         /**
  29          * @param DatabaseBase $db
  30          * @param string $table
  31          * @param string $field
  32          * @return null|PostgresField
  33          */
  34         static function fromText( $db, $table, $field ) {
  35                 $q = <<<SQL
  36 SELECT
  37  attnotnull, attlen, conname AS conname,
  38  atthasdef,
  39  adsrc,
  40  COALESCE(condeferred, 'f') AS deferred,
  41  COALESCE(condeferrable, 'f') AS deferrable,
  42  CASE WHEN typname = 'int2' THEN 'smallint'
  43   WHEN typname = 'int4' THEN 'integer'
  44   WHEN typname = 'int8' THEN 'bigint'
  45   WHEN typname = 'bpchar' THEN 'char'
  46  ELSE typname END AS typname
  47 FROM pg_class c
  48 JOIN pg_namespace n ON (n.oid = c.relnamespace)
  49 JOIN pg_attribute a ON (a.attrelid = c.oid)
  50 JOIN pg_type t ON (t.oid = a.atttypid)
  51 LEFT JOIN pg_constraint o ON (o.conrelid = c.oid AND a.attnum = ANY(o.conkey) AND o.contype = 'f')
  52 LEFT JOIN pg_attrdef d on c.oid=d.adrelid and a.attnum=d.adnum
  53 WHERE relkind = 'r'
  54 AND nspname=%s
  55 AND relname=%s
  56 AND attname=%s;
  57 SQL;
  58
  59                 $table = $db->tableName( $table, 'raw' );
  60                 $res = $db->query(
  61                         sprintf( $q,
  62                                 $db->addQuotes( $db->getCoreSchema() ),
  63                                 $db->addQuotes( $table ),
  64                                 $db->addQuotes( $field )
  65                         )
  66                 );
  67                 $row = $db->fetchObject( $res );
  68                 if ( !$row ) {
  69                         return null;
  70                 }
  71                 $n = new PostgresField;
  72                 $n->type = $row->typname;
  73                 $n->nullable = ( $row->attnotnull == 'f' );
  74                 $n->name = $field;
  75                 $n->tablename = $table;
  76                 $n->max_length = $row->attlen;
  77                 $n->deferrable = ( $row->deferrable == 't' );
  78                 $n->deferred = ( $row->deferred == 't' );
  79                 $n->conname = $row->conname;
  80                 $n->has_default = ( $row->atthasdef === 't' );
  81                 $n->default = $row->adsrc;
  82
  83                 return $n;
  84         }
  85
  86         function name() {
  87                 return $this->name;
  88         }
  89
  90         function tableName() {
  91                 return $this->tablename;
  92         }
  93
  94         function type() {
  95                 return $this->type;
  96         }
  97
  98         function isNullable() {
  99                 return $this->nullable;
 100         }
 101
 102         function maxLength() {
 103                 return $this->max_length;
 104         }
 105
 106         function is_deferrable() {
 107                 return $this->deferrable;
 108         }
 109
 110         function is_deferred() {
 111                 return $this->deferred;
 112         }
 113
 114         function conname() {
 115                 return $this->conname;
 116         }
 117
 118         /**
 119          * @since 1.19
 120          */
 121         function defaultValue() {
 122                 if ( $this->has_default ) {
 123                         return $this->default;
 124                 } else {
 125                         return false;
 126                 }
 127         }
 128 }
 129
 130 /**
 131  * Used to debug transaction processing
 132  * Only used if $wgDebugDBTransactions is true
 133  *
 134  * @since 1.19
 135  * @ingroup Database
 136  */
 137 class PostgresTransactionState {
 138         private static $WATCHED = array(
 139                 array(
 140                         "desc" => "%s: Connection state changed from %s -> %s\n",
 141                         "states" => array(
 142                                 PGSQL_CONNECTION_OK => "OK",
 143                                 PGSQL_CONNECTION_BAD => "BAD"
 144                         )
 145                 ),
 146                 array(
 147                         "desc" => "%s: Transaction state changed from %s -> %s\n",
 148                         "states" => array(
 149                                 PGSQL_TRANSACTION_IDLE => "IDLE",
 150                                 PGSQL_TRANSACTION_ACTIVE => "ACTIVE",
 151                                 PGSQL_TRANSACTION_INTRANS => "TRANS",
 152                                 PGSQL_TRANSACTION_INERROR => "ERROR",
 153                                 PGSQL_TRANSACTION_UNKNOWN => "UNKNOWN"
 154                         )
 155                 )
 156         );
 157
 158         /** @var array */
 159         private $mNewState;
 160
 161         /** @var array */
 162         private $mCurrentState;
 163
 164         public function __construct( $conn ) {
 165                 $this->mConn = $conn;
 166                 $this->update();
 167                 $this->mCurrentState = $this->mNewState;
 168         }
 169
 170         public function update() {
 171                 $this->mNewState = array(
 172                         pg_connection_status( $this->mConn ),
 173                         pg_transaction_status( $this->mConn )
 174                 );
 175         }
 176
 177         public function check() {
 178                 global $wgDebugDBTransactions;
 179                 $this->update();
 180                 if ( $wgDebugDBTransactions ) {
 181                         if ( $this->mCurrentState !== $this->mNewState ) {
 182                                 $old = reset( $this->mCurrentState );
 183                                 $new = reset( $this->mNewState );
 184                                 foreach ( self::$WATCHED as $watched ) {
 185                                         if ( $old !== $new ) {
 186                                                 $this->log_changed( $old, $new, $watched );
 187                                         }
 188                                         $old = next( $this->mCurrentState );
 189                                         $new = next( $this->mNewState );
 190                                 }
 191                         }
 192                 }
 193                 $this->mCurrentState = $this->mNewState;
 194         }
 195
 196         protected function describe_changed( $status, $desc_table ) {
 197                 if ( isset( $desc_table[$status] ) ) {
 198                         return $desc_table[$status];
 199                 } else {
 200                         return "STATUS " . $status;
 201                 }
 202         }
 203
 204         protected function log_changed( $old, $new, $watched ) {
 205                 wfDebug( sprintf( $watched["desc"],
 206                         $this->mConn,
 207                         $this->describe_changed( $old, $watched["states"] ),
 208                         $this->describe_changed( $new, $watched["states"] )
 209                 ) );
 210         }
 211 }
 212
 213 /**
 214  * Manage savepoints within a transaction
 215  * @ingroup Database
 216  * @since 1.19
 217  */
 218 class SavepointPostgres {
 219         /** @var DatabaseBase Establish a savepoint within a transaction */
 220         protected $dbw;
 221         protected $id;
 222         protected $didbegin;
 223
 224         /**
 225          * @param DatabaseBase $dbw
 226          * @param $id
 227          */
 228         public function __construct( $dbw, $id ) {
 229                 $this->dbw = $dbw;
 230                 $this->id = $id;
 231                 $this->didbegin = false;
 232                 /* If we are not in a transaction, we need to be for savepoint trickery */
 233                 if ( !$dbw->trxLevel() ) {
 234                         $dbw->begin( "FOR SAVEPOINT" );
 235                         $this->didbegin = true;
 236                 }
 237         }
 238
 239         public function __destruct() {
 240                 if ( $this->didbegin ) {
 241                         $this->dbw->rollback();
 242                         $this->didbegin = false;
 243                 }
 244         }
 245
 246         public function commit() {
 247                 if ( $this->didbegin ) {
 248                         $this->dbw->commit();
 249                         $this->didbegin = false;
 250                 }
 251         }
 252
 253         protected function query( $keyword, $msg_ok, $msg_failed ) {
 254                 global $wgDebugDBTransactions;
 255                 if ( $this->dbw->doQuery( $keyword . " " . $this->id ) !== false ) {
 256                         if ( $wgDebugDBTransactions ) {
 257                                 wfDebug( sprintf( $msg_ok, $this->id ) );
 258                         }
 259                 } else {
 260                         wfDebug( sprintf( $msg_failed, $this->id ) );
 261                 }
 262         }
 263
 264         public function savepoint() {
 265                 $this->query( "SAVEPOINT",
 266                         "Transaction state: savepoint \"%s\" established.\n",
 267                         "Transaction state: establishment of savepoint \"%s\" FAILED.\n"
 268                 );
 269         }
 270
 271         public function release() {
 272                 $this->query( "RELEASE",
 273                         "Transaction state: savepoint \"%s\" released.\n",
 274                         "Transaction state: release of savepoint \"%s\" FAILED.\n"
 275                 );
 276         }
 277
 278         public function rollback() {
 279                 $this->query( "ROLLBACK TO",
 280                         "Transaction state: savepoint \"%s\" rolled back.\n",
 281                         "Transaction state: rollback of savepoint \"%s\" FAILED.\n"
 282                 );
 283         }
 284
 285         public function __toString() {
 286                 return (string)$this->id;
 287         }
 288 }
 289
 290 /**
 291  * @ingroup Database
 292  */
 293 class DatabasePostgres extends DatabaseBase {
 294         /** @var resource */
 295         protected $mLastResult = null;
 296
 297         /** @var int The number of rows affected as an integer */
 298         protected $mAffectedRows = null;
 299
 300         /** @var int */
 301         private $mInsertId = null;
 302
 303         /** @var float|string */
 304         private $numericVersion = null;
 305
 306         /** @var string Connect string to open a PostgreSQL connection */
 307         private $connectString;
 308
 309         /** @var PostgresTransactionState */
 310         private $mTransactionState;
 311
 312         /** @var string */
 313         private $mCoreSchema;
 314
 315         function getType() {
 316                 return 'postgres';
 317         }
 318
 319         function cascadingDeletes() {
 320                 return true;
 321         }
 322
 323         function cleanupTriggers() {
 324                 return true;
 325         }
 326
 327         function strictIPs() {
 328                 return true;
 329         }
 330
 331         function realTimestamps() {
 332                 return true;
 333         }
 334
 335         function implicitGroupby() {
 336                 return false;
 337         }
 338
 339         function implicitOrderby() {
 340                 return false;
 341         }
 342
 343         function searchableIPs() {
 344                 return true;
 345         }
 346
 347         function functionalIndexes() {
 348                 return true;
 349         }
 350
 351         function hasConstraint( $name ) {
 352                 $SQL = "SELECT 1 FROM pg_catalog.pg_constraint c, pg_catalog.pg_namespace n " .
 353                         "WHERE c.connamespace = n.oid AND conname = '" .
 354                         pg_escape_string( $this->mConn, $name ) . "' AND n.nspname = '" .
 355                         pg_escape_string( $this->mConn, $this->getCoreSchema() ) . "'";
 356                 $res = $this->doQuery( $SQL );
 357
 358                 return $this->numRows( $res );
 359         }
 360
 361         /**
 362          * Usually aborts on failure
 363          * @param string $server
 364          * @param string $user
 365          * @param string $password
 366          * @param string $dbName
 367          * @throws DBConnectionError|Exception
 368          * @return DatabaseBase|null
 369          */
 370         function open( $server, $user, $password, $dbName ) {
 371                 # Test for Postgres support, to avoid suppressed fatal error
 372                 if ( !function_exists( 'pg_connect' ) ) {
 373                         throw new DBConnectionError(
 374                                 $this,
 375                                 "Postgres functions missing, have you compiled PHP with the --with-pgsql\n" .
 376                                 "option? (Note: if you recently installed PHP, you may need to restart your\n" .
 377                                 "webserver and database)\n"
 378                         );
 379                 }
 380
 381                 global $wgDBport;
 382
 383                 if ( !strlen( $user ) ) { # e.g. the class is being loaded
 384                         return null;
 385                 }
 386
 387                 $this->mServer = $server;
 388                 $port = $wgDBport;
 389                 $this->mUser = $user;
 390                 $this->mPassword = $password;
 391                 $this->mDBname = $dbName;
 392
 393                 $connectVars = array(
 394                         'dbname' => $dbName,
 395                         'user' => $user,
 396                         'password' => $password
 397                 );
 398                 if ( $server != false && $server != '' ) {
 399                         $connectVars['host'] = $server;
 400                 }
 401                 if ( $port != false && $port != '' ) {
 402                         $connectVars['port'] = $port;
 403                 }
 404                 if ( $this->mFlags & DBO_SSL ) {
 405                         $connectVars['sslmode'] = 1;
 406                 }
 407
 408                 $this->connectString = $this->makeConnectionString( $connectVars, PGSQL_CONNECT_FORCE_NEW );
 409                 $this->close();
 410                 $this->installErrorHandler();
 411
 412                 try {
 413                         $this->mConn = pg_connect( $this->connectString );
 414                 } catch ( Exception $ex ) {
 415                         $this->restoreErrorHandler();
 416                         throw $ex;
 417                 }
 418
 419                 $phpError = $this->restoreErrorHandler();
 420
 421                 if ( !$this->mConn ) {
 422                         wfDebug( "DB connection error\n" );
 423                         wfDebug( "Server: $server, Database: $dbName, User: $user, Password: " .
 424                                 substr( $password, 0, 3 ) . "...\n" );
 425                         wfDebug( $this->lastError() . "\n" );
 426                         throw new DBConnectionError( $this, str_replace( "\n", ' ', $phpError ) );
 427                 }
 428
 429                 $this->mOpened = true;
 430                 $this->mTransactionState = new PostgresTransactionState( $this->mConn );
 431
 432                 global $wgCommandLineMode;
 433                 # If called from the command-line (e.g. importDump), only show errors
 434                 if ( $wgCommandLineMode ) {
 435                         $this->doQuery( "SET client_min_messages = 'ERROR'" );
 436                 }
 437
 438                 $this->query( "SET client_encoding='UTF8'", __METHOD__ );
 439                 $this->query( "SET datestyle = 'ISO, YMD'", __METHOD__ );
 440                 $this->query( "SET timezone = 'GMT'", __METHOD__ );
 441                 $this->query( "SET standard_conforming_strings = on", __METHOD__ );
 442                 if ( $this->getServerVersion() >= 9.0 ) {
 443                         $this->query( "SET bytea_output = 'escape'", __METHOD__ ); // PHP bug 53127
 444                 }
 445
 446                 global $wgDBmwschema;
 447                 $this->determineCoreSchema( $wgDBmwschema );
 448
 449                 return $this->mConn;
 450         }
 451
 452         /**
 453          * Postgres doesn't support selectDB in the same way MySQL does. So if the
 454          * DB name doesn't match the open connection, open a new one
 455          * @param string $db
 456          * @return bool
 457          */
 458         function selectDB( $db ) {
 459                 if ( $this->mDBname !== $db ) {
 460                         return (bool)$this->open( $this->mServer, $this->mUser, $this->mPassword, $db );
 461                 } else {
 462                         return true;
 463                 }
 464         }
 465
 466         function makeConnectionString( $vars ) {
 467                 $s = '';
 468                 foreach ( $vars as $name => $value ) {
 469                         $s .= "$name='" . str_replace( "'", "\\'", $value ) . "' ";
 470                 }
 471
 472                 return $s;
 473         }
 474
 475         /**
 476          * Closes a database connection, if it is open
 477          * Returns success, true if already closed
 478          * @return bool
 479          */
 480         protected function closeConnection() {
 481                 return pg_close( $this->mConn );
 482         }
 483
 484         public function doQuery( $sql ) {
 485                 if ( function_exists( 'mb_convert_encoding' ) ) {
 486                         $sql = mb_convert_encoding( $sql, 'UTF-8' );
 487                 }
 488                 $this->mTransactionState->check();
 489                 if ( pg_send_query( $this->mConn, $sql ) === false ) {
 490                         throw new DBUnexpectedError( $this, "Unable to post new query to PostgreSQL\n" );
 491                 }
 492                 $this->mLastResult = pg_get_result( $this->mConn );
 493                 $this->mTransactionState->check();
 494                 $this->mAffectedRows = null;
 495                 if ( pg_result_error( $this->mLastResult ) ) {
 496                         return false;
 497                 }
 498
 499                 return $this->mLastResult;
 500         }
 501
 502         protected function dumpError() {
 503                 $diags = array(
 504                         PGSQL_DIAG_SEVERITY,
 505                         PGSQL_DIAG_SQLSTATE,
 506                         PGSQL_DIAG_MESSAGE_PRIMARY,
 507                         PGSQL_DIAG_MESSAGE_DETAIL,
 508                         PGSQL_DIAG_MESSAGE_HINT,
 509                         PGSQL_DIAG_STATEMENT_POSITION,
 510                         PGSQL_DIAG_INTERNAL_POSITION,
 511                         PGSQL_DIAG_INTERNAL_QUERY,
 512                         PGSQL_DIAG_CONTEXT,
 513                         PGSQL_DIAG_SOURCE_FILE,
 514                         PGSQL_DIAG_SOURCE_LINE,
 515                         PGSQL_DIAG_SOURCE_FUNCTION
 516                 );
 517                 foreach ( $diags as $d ) {
 518                         wfDebug( sprintf( "PgSQL ERROR(%d): %s\n",
 519                                 $d, pg_result_error_field( $this->mLastResult, $d ) ) );
 520                 }
 521         }
 522
 523         function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
 524                 /* Transaction stays in the ERROR state until rolledback */
 525                 if ( $tempIgnore ) {
 526                         /* Check for constraint violation */
 527                         if ( $errno === '23505' ) {
 528                                 parent::reportQueryError( $error, $errno, $sql, $fname, $tempIgnore );
 529
 530                                 return;
 531                         }
 532                 }
 533                 /* Don't ignore serious errors */
 534                 $this->rollback( __METHOD__ );
 535                 parent::reportQueryError( $error, $errno, $sql, $fname, false );
 536         }
 537
 538         function queryIgnore( $sql, $fname = __METHOD__ ) {
 539                 return $this->query( $sql, $fname, true );
 540         }
 541
 542         /**
 543          * @param stdClass|ResultWrapper $res
 544          * @throws DBUnexpectedError
 545          */
 546         function freeResult( $res ) {
 547                 if ( $res instanceof ResultWrapper ) {
 548                         $res = $res->result;
 549                 }
 550                 wfSuppressWarnings();
 551                 $ok = pg_free_result( $res );
 552                 wfRestoreWarnings();
 553                 if ( !$ok ) {
 554                         throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 555                 }
 556         }
 557
 558         /**
 559          * @param ResultWrapper|stdClass $res
 560          * @return stdClass
 561          * @throws DBUnexpectedError
 562          */
 563         function fetchObject( $res ) {
 564                 if ( $res instanceof ResultWrapper ) {
 565                         $res = $res->result;
 566                 }
 567                 wfSuppressWarnings();
 568                 $row = pg_fetch_object( $res );
 569                 wfRestoreWarnings();
 570                 # @todo FIXME: HACK HACK HACK HACK debug
 571
 572                 # @todo hashar: not sure if the following test really trigger if the object
 573                 #          fetching failed.
 574                 if ( pg_last_error( $this->mConn ) ) {
 575                         throw new DBUnexpectedError(
 576                                 $this,
 577                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 578                         );
 579                 }
 580
 581                 return $row;
 582         }
 583
 584         function fetchRow( $res ) {
 585                 if ( $res instanceof ResultWrapper ) {
 586                         $res = $res->result;
 587                 }
 588                 wfSuppressWarnings();
 589                 $row = pg_fetch_array( $res );
 590                 wfRestoreWarnings();
 591                 if ( pg_last_error( $this->mConn ) ) {
 592                         throw new DBUnexpectedError(
 593                                 $this,
 594                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 595                         );
 596                 }
 597
 598                 return $row;
 599         }
 600
 601         function numRows( $res ) {
 602                 if ( $res instanceof ResultWrapper ) {
 603                         $res = $res->result;
 604                 }
 605                 wfSuppressWarnings();
 606                 $n = pg_num_rows( $res );
 607                 wfRestoreWarnings();
 608                 if ( pg_last_error( $this->mConn ) ) {
 609                         throw new DBUnexpectedError(
 610                                 $this,
 611                                 'SQL error: ' . htmlspecialchars( pg_last_error( $this->mConn ) )
 612                         );
 613                 }
 614
 615                 return $n;
 616         }
 617
 618         function numFields( $res ) {
 619                 if ( $res instanceof ResultWrapper ) {
 620                         $res = $res->result;
 621                 }
 622
 623                 return pg_num_fields( $res );
 624         }
 625
 626         function fieldName( $res, $n ) {
 627                 if ( $res instanceof ResultWrapper ) {
 628                         $res = $res->result;
 629                 }
 630
 631                 return pg_field_name( $res, $n );
 632         }
 633
 634         /**
 635          * Return the result of the last call to nextSequenceValue();
 636          * This must be called after nextSequenceValue().
 637          *
 638          * @return int|null
 639          */
 640         function insertId() {
 641                 return $this->mInsertId;
 642         }
 643
 644         /**
 645          * @param mixed $res
 646          * @param int $row
 647          * @return bool
 648          */
 649         function dataSeek( $res, $row ) {
 650                 if ( $res instanceof ResultWrapper ) {
 651                         $res = $res->result;
 652                 }
 653
 654                 return pg_result_seek( $res, $row );
 655         }
 656
 657         function lastError() {
 658                 if ( $this->mConn ) {
 659                         if ( $this->mLastResult ) {
 660                                 return pg_result_error( $this->mLastResult );
 661                         } else {
 662                                 return pg_last_error();
 663                         }
 664                 } else {
 665                         return 'No database connection';
 666                 }
 667         }
 668
 669         function lastErrno() {
 670                 if ( $this->mLastResult ) {
 671                         return pg_result_error_field( $this->mLastResult, PGSQL_DIAG_SQLSTATE );
 672                 } else {
 673                         return false;
 674                 }
 675         }
 676
 677         function affectedRows() {
 678                 if ( !is_null( $this->mAffectedRows ) ) {
 679                         // Forced result for simulated queries
 680                         return $this->mAffectedRows;
 681                 }
 682                 if ( empty( $this->mLastResult ) ) {
 683                         return 0;
 684                 }
 685
 686                 return pg_affected_rows( $this->mLastResult );
 687         }
 688
 689         /**
 690          * Estimate rows in dataset
 691          * Returns estimated count, based on EXPLAIN output
 692          * This is not necessarily an accurate estimate, so use sparingly
 693          * Returns -1 if count cannot be found
 694          * Takes same arguments as Database::select()
 695          *
 696          * @param string $table
 697          * @param string $vars
 698          * @param string $conds
 699          * @param string $fname
 700          * @param array $options
 701          * @return int
 702          */
 703         function estimateRowCount( $table, $vars = '*', $conds = '',
 704                 $fname = __METHOD__, $options = array()
 705         ) {
 706                 $options['EXPLAIN'] = true;
 707                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 708                 $rows = -1;
 709                 if ( $res ) {
 710                         $row = $this->fetchRow( $res );
 711                         $count = array();
 712                         if ( preg_match( '/rows=(\d+)/', $row[0], $count ) ) {
 713                                 $rows = $count[1];
 714                         }
 715                 }
 716
 717                 return $rows;
 718         }
 719
 720         /**
 721          * Returns information about an index
 722          * If errors are explicitly ignored, returns NULL on failure
 723          *
 724          * @param string $table
 725          * @param string $index
 726          * @param string $fname
 727          * @return bool|null
 728          */
 729         function indexInfo( $table, $index, $fname = __METHOD__ ) {
 730                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='$table'";
 731                 $res = $this->query( $sql, $fname );
 732                 if ( !$res ) {
 733                         return null;
 734                 }
 735                 foreach ( $res as $row ) {
 736                         if ( $row->indexname == $this->indexName( $index ) ) {
 737                                 return $row;
 738                         }
 739                 }
 740
 741                 return false;
 742         }
 743
 744         /**
 745          * Returns is of attributes used in index
 746          *
 747          * @since 1.19
 748          * @param string $index
 749          * @param bool|string $schema
 750          * @return array
 751          */
 752         function indexAttributes( $index, $schema = false ) {
 753                 if ( $schema === false ) {
 754                         $schema = $this->getCoreSchema();
 755                 }
 756                 /*
 757                  * A subquery would be not needed if we didn't care about the order
 758                  * of attributes, but we do
 759                  */
 760                 $sql = <<<__INDEXATTR__
 761
 762                         SELECT opcname,
 763                                 attname,
 764                                 i.indoption[s.g] as option,
 765                                 pg_am.amname
 766                         FROM
 767                                 (SELECT generate_series(array_lower(isub.indkey,1), array_upper(isub.indkey,1)) AS g
 768                                         FROM
 769                                                 pg_index isub
 770                                         JOIN pg_class cis
 771                                                 ON cis.oid=isub.indexrelid
 772                                         JOIN pg_namespace ns
 773                                                 ON cis.relnamespace = ns.oid
 774                                         WHERE cis.relname='$index' AND ns.nspname='$schema') AS s,
 775                                 pg_attribute,
 776                                 pg_opclass opcls,
 777                                 pg_am,
 778                                 pg_class ci
 779                                 JOIN pg_index i
 780                                         ON ci.oid=i.indexrelid
 781                                 JOIN pg_class ct
 782                                         ON ct.oid = i.indrelid
 783                                 JOIN pg_namespace n
 784                                         ON ci.relnamespace = n.oid
 785                                 WHERE
 786                                         ci.relname='$index' AND n.nspname='$schema'
 787                                         AND     attrelid = ct.oid
 788                                         AND     i.indkey[s.g] = attnum
 789                                         AND     i.indclass[s.g] = opcls.oid
 790                                         AND     pg_am.oid = opcls.opcmethod
 791 __INDEXATTR__;
 792                 $res = $this->query( $sql, __METHOD__ );
 793                 $a = array();
 794                 if ( $res ) {
 795                         foreach ( $res as $row ) {
 796                                 $a[] = array(
 797                                         $row->attname,
 798                                         $row->opcname,
 799                                         $row->amname,
 800                                         $row->option );
 801                         }
 802                 } else {
 803                         return null;
 804                 }
 805
 806                 return $a;
 807         }
 808
 809         function indexUnique( $table, $index, $fname = __METHOD__ ) {
 810                 $sql = "SELECT indexname FROM pg_indexes WHERE tablename='{$table}'" .
 811                         " AND indexdef LIKE 'CREATE UNIQUE%(" .
 812                         $this->strencode( $this->indexName( $index ) ) .
 813                         ")'";
 814                 $res = $this->query( $sql, $fname );
 815                 if ( !$res ) {
 816                         return null;
 817                 }
 818
 819                 return $res->numRows() > 0;
 820         }
 821
 822         /**
 823          * INSERT wrapper, inserts an array into a table
 824          *
 825          * $args may be a single associative array, or an array of these with numeric keys,
 826          * for multi-row insert (Postgres version 8.2 and above only).
 827          *
 828          * @param string $table Name of the table to insert to.
 829          * @param array $args Items to insert into the table.
 830          * @param string $fname Name of the function, for profiling
 831          * @param array|string $options String or array. Valid options: IGNORE
 832          * @return bool Success of insert operation. IGNORE always returns true.
 833          */
 834         function insert( $table, $args, $fname = __METHOD__, $options = array() ) {
 835                 if ( !count( $args ) ) {
 836                         return true;
 837                 }
 838
 839                 $table = $this->tableName( $table );
 840                 if ( !isset( $this->numericVersion ) ) {
 841                         $this->getServerVersion();
 842                 }
 843
 844                 if ( !is_array( $options ) ) {
 845                         $options = array( $options );
 846                 }
 847
 848                 if ( isset( $args[0] ) && is_array( $args[0] ) ) {
 849                         $multi = true;
 850                         $keys = array_keys( $args[0] );
 851                 } else {
 852                         $multi = false;
 853                         $keys = array_keys( $args );
 854                 }
 855
 856                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 857                 $savepoint = null;
 858                 if ( in_array( 'IGNORE', $options ) ) {
 859                         $savepoint = new SavepointPostgres( $this, 'mw' );
 860                         $olde = error_reporting( 0 );
 861                         // For future use, we may want to track the number of actual inserts
 862                         // Right now, insert (all writes) simply return true/false
 863                         $numrowsinserted = 0;
 864                 }
 865
 866                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
 867
 868                 if ( $multi ) {
 869                         if ( $this->numericVersion >= 8.2 && !$savepoint ) {
 870                                 $first = true;
 871                                 foreach ( $args as $row ) {
 872                                         if ( $first ) {
 873                                                 $first = false;
 874                                         } else {
 875                                                 $sql .= ',';
 876                                         }
 877                                         $sql .= '(' . $this->makeList( $row ) . ')';
 878                                 }
 879                                 $res = (bool)$this->query( $sql, $fname, $savepoint );
 880                         } else {
 881                                 $res = true;
 882                                 $origsql = $sql;
 883                                 foreach ( $args as $row ) {
 884                                         $tempsql = $origsql;
 885                                         $tempsql .= '(' . $this->makeList( $row ) . ')';
 886
 887                                         if ( $savepoint ) {
 888                                                 $savepoint->savepoint();
 889                                         }
 890
 891                                         $tempres = (bool)$this->query( $tempsql, $fname, $savepoint );
 892
 893                                         if ( $savepoint ) {
 894                                                 $bar = pg_last_error();
 895                                                 if ( $bar != false ) {
 896                                                         $savepoint->rollback();
 897                                                 } else {
 898                                                         $savepoint->release();
 899                                                         $numrowsinserted++;
 900                                                 }
 901                                         }
 902
 903                                         // If any of them fail, we fail overall for this function call
 904                                         // Note that this will be ignored if IGNORE is set
 905                                         if ( !$tempres ) {
 906                                                 $res = false;
 907                                         }
 908                                 }
 909                         }
 910                 } else {
 911                         // Not multi, just a lone insert
 912                         if ( $savepoint ) {
 913                                 $savepoint->savepoint();
 914                         }
 915
 916                         $sql .= '(' . $this->makeList( $args ) . ')';
 917                         $res = (bool)$this->query( $sql, $fname, $savepoint );
 918                         if ( $savepoint ) {
 919                                 $bar = pg_last_error();
 920                                 if ( $bar != false ) {
 921                                         $savepoint->rollback();
 922                                 } else {
 923                                         $savepoint->release();
 924                                         $numrowsinserted++;
 925                                 }
 926                         }
 927                 }
 928                 if ( $savepoint ) {
 929                         error_reporting( $olde );
 930                         $savepoint->commit();
 931
 932                         // Set the affected row count for the whole operation
 933                         $this->mAffectedRows = $numrowsinserted;
 934
 935                         // IGNORE always returns true
 936                         return true;
 937                 }
 938
 939                 return $res;
 940         }
 941
 942         /**
 943          * INSERT SELECT wrapper
 944          * $varMap must be an associative array of the form array( 'dest1' => 'source1', ...)
 945          * Source items may be literals rather then field names, but strings should
 946          * be quoted with Database::addQuotes()
 947          * $conds may be "*" to copy the whole table
 948          * srcTable may be an array of tables.
 949          * @todo FIXME: Implement this a little better (seperate select/insert)?
 950          *
 951          * @param string $destTable
 952          * @param array|string $srcTable
 953          * @param array $varMap
 954          * @param array $conds
 955          * @param string $fname
 956          * @param array $insertOptions
 957          * @param array $selectOptions
 958          * @return bool
 959          */
 960         function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 961                 $insertOptions = array(), $selectOptions = array() ) {
 962                 $destTable = $this->tableName( $destTable );
 963
 964                 if ( !is_array( $insertOptions ) ) {
 965                         $insertOptions = array( $insertOptions );
 966                 }
 967
 968                 /*
 969                  * If IGNORE is set, we use savepoints to emulate mysql's behavior
 970                  * Ignore LOW PRIORITY option, since it is MySQL-specific
 971                  */
 972                 $savepoint = null;
 973                 if ( in_array( 'IGNORE', $insertOptions ) ) {
 974                         $savepoint = new SavepointPostgres( $this, 'mw' );
 975                         $olde = error_reporting( 0 );
 976                         $numrowsinserted = 0;
 977                         $savepoint->savepoint();
 978                 }
 979
 980                 if ( !is_array( $selectOptions ) ) {
 981                         $selectOptions = array( $selectOptions );
 982                 }
 983                 list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
 984                 if ( is_array( $srcTable ) ) {
 985                         $srcTable = implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
 986                 } else {
 987                         $srcTable = $this->tableName( $srcTable );
 988                 }
 989
 990                 $sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
 991                         " SELECT $startOpts " . implode( ',', $varMap ) .
 992                         " FROM $srcTable $useIndex";
 993
 994                 if ( $conds != '*' ) {
 995                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
 996                 }
 997
 998                 $sql .= " $tailOpts";
 999
1000                 $res = (bool)$this->query( $sql, $fname, $savepoint );
1001                 if ( $savepoint ) {
1002                         $bar = pg_last_error();
1003                         if ( $bar != false ) {
1004                                 $savepoint->rollback();
1005                         } else {
1006                                 $savepoint->release();
1007                                 $numrowsinserted++;
1008                         }
1009                         error_reporting( $olde );
1010                         $savepoint->commit();
1011
1012                         // Set the affected row count for the whole operation
1013                         $this->mAffectedRows = $numrowsinserted;
1014
1015                         // IGNORE always returns true
1016                         return true;
1017                 }
1018
1019                 return $res;
1020         }
1021
1022         function tableName( $name, $format = 'quoted' ) {
1023                 # Replace reserved words with better ones
1024                 switch ( $name ) {
1025                         case 'user':
1026                                 return $this->realTableName( 'mwuser', $format );
1027                         case 'text':
1028                                 return $this->realTableName( 'pagecontent', $format );
1029                         default:
1030                                 return $this->realTableName( $name, $format );
1031                 }
1032         }
1033
1034         /* Don't cheat on installer */
1035         function realTableName( $name, $format = 'quoted' ) {
1036                 return parent::tableName( $name, $format );
1037         }
1038
1039         /**
1040          * Return the next in a sequence, save the value for retrieval via insertId()
1041          *
1042          * @param string $seqName
1043          * @return int|null
1044          */
1045         function nextSequenceValue( $seqName ) {
1046                 $safeseq = str_replace( "'", "''", $seqName );
1047                 $res = $this->query( "SELECT nextval('$safeseq')" );
1048                 $row = $this->fetchRow( $res );
1049                 $this->mInsertId = $row[0];
1050
1051                 return $this->mInsertId;
1052         }
1053
1054         /**
1055          * Return the current value of a sequence. Assumes it has been nextval'ed in this session.
1056          *
1057          * @param string $seqName
1058          * @return int
1059          */
1060         function currentSequenceValue( $seqName ) {
1061                 $safeseq = str_replace( "'", "''", $seqName );
1062                 $res = $this->query( "SELECT currval('$safeseq')" );
1063                 $row = $this->fetchRow( $res );
1064                 $currval = $row[0];
1065
1066                 return $currval;
1067         }
1068
1069         # Returns the size of a text field, or -1 for "unlimited"
1070         function textFieldSize( $table, $field ) {
1071                 $table = $this->tableName( $table );
1072                 $sql = "SELECT t.typname as ftype,a.atttypmod as size
1073                         FROM pg_class c, pg_attribute a, pg_type t
1074                         WHERE relname='$table' AND a.attrelid=c.oid AND
1075                                 a.atttypid=t.oid and a.attname='$field'";
1076                 $res = $this->query( $sql );
1077                 $row = $this->fetchObject( $res );
1078                 if ( $row->ftype == 'varchar' ) {
1079                         $size = $row->size - 4;
1080                 } else {
1081                         $size = $row->size;
1082                 }
1083
1084                 return $size;
1085         }
1086
1087         function limitResult( $sql, $limit, $offset = false ) {
1088                 return "$sql LIMIT $limit " . ( is_numeric( $offset ) ? " OFFSET {$offset} " : '' );
1089         }
1090
1091         function wasDeadlock() {
1092                 return $this->lastErrno() == '40P01';
1093         }
1094
1095         function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = __METHOD__ ) {
1096                 $newName = $this->addIdentifierQuotes( $newName );
1097                 $oldName = $this->addIdentifierQuotes( $oldName );
1098
1099                 return $this->query( 'CREATE ' . ( $temporary ? 'TEMPORARY ' : '' ) . " TABLE $newName " .
1100                         "(LIKE $oldName INCLUDING DEFAULTS)", $fname );
1101         }
1102
1103         function listTables( $prefix = null, $fname = __METHOD__ ) {
1104                 $eschema = $this->addQuotes( $this->getCoreSchema() );
1105                 $result = $this->query( "SELECT tablename FROM pg_tables WHERE schemaname = $eschema", $fname );
1106                 $endArray = array();
1107
1108                 foreach ( $result as $table ) {
1109                         $vars = get_object_vars( $table );
1110                         $table = array_pop( $vars );
1111                         if ( !$prefix || strpos( $table, $prefix ) === 0 ) {
1112                                 $endArray[] = $table;
1113                         }
1114                 }
1115
1116                 return $endArray;
1117         }
1118
1119         function timestamp( $ts = 0 ) {
1120                 return wfTimestamp( TS_POSTGRES, $ts );
1121         }
1122
1123         /*
1124          * Posted by cc[plus]php[at]c2se[dot]com on 25-Mar-2009 09:12
1125          * to http://www.php.net/manual/en/ref.pgsql.php
1126          *
1127          * Parsing a postgres array can be a tricky problem, he's my
1128          * take on this, it handles multi-dimensional arrays plus
1129          * escaping using a nasty regexp to determine the limits of each
1130          * data-item.
1131          *
1132          * This should really be handled by PHP PostgreSQL module
1133          *
1134          * @since 1.19
1135          * @param string $text Postgreql array returned in a text form like {a,b}
1136          * @param string $output
1137          * @param int $limit
1138          * @param int $offset
1139          * @return string
1140          */
1141         function pg_array_parse( $text, &$output, $limit = false, $offset = 1 ) {
1142                 if ( false === $limit ) {
1143                         $limit = strlen( $text ) - 1;
1144                         $output = array();
1145                 }
1146                 if ( '{}' == $text ) {
1147                         return $output;
1148                 }
1149                 do {
1150                         if ( '{' != $text[$offset] ) {
1151                                 preg_match( "/(\\{?\"([^\"\\\\]|\\\\.)*\"|[^,{}]+)+([,}]+)/",
1152                                         $text, $match, 0, $offset );
1153                                 $offset += strlen( $match[0] );
1154                                 $output[] = ( '"' != $match[1][0]
1155                                         ? $match[1]
1156                                         : stripcslashes( substr( $match[1], 1, -1 ) ) );
1157                                 if ( '},' == $match[3] ) {
1158                                         return $output;
1159                                 }
1160                         } else {
1161                                 $offset = $this->pg_array_parse( $text, $output, $limit, $offset + 1 );
1162                         }
1163                 } while ( $limit > $offset );
1164
1165                 return $output;
1166         }
1167
1168         /**
1169          * Return aggregated value function call
1170          */
1171         public function aggregateValue( $valuedata, $valuename = 'value' ) {
1172                 return $valuedata;
1173         }
1174
1175         /**
1176          * @return string Wikitext of a link to the server software's web site
1177          */
1178         public function getSoftwareLink() {
1179                 return '[http://www.postgresql.org/ PostgreSQL]';
1180         }
1181
1182         /**
1183          * Return current schema (executes SELECT current_schema())
1184          * Needs transaction
1185          *
1186          * @since 1.19
1187          * @return string Default schema for the current session
1188          */
1189         function getCurrentSchema() {
1190                 $res = $this->query( "SELECT current_schema()", __METHOD__ );
1191                 $row = $this->fetchRow( $res );
1192
1193                 return $row[0];
1194         }
1195
1196         /**
1197          * Return list of schemas which are accessible without schema name
1198          * This is list does not contain magic keywords like "$user"
1199          * Needs transaction
1200          *
1201          * @see getSearchPath()
1202          * @see setSearchPath()
1203          * @since 1.19
1204          * @return array list of actual schemas for the current sesson
1205          */
1206         function getSchemas() {
1207                 $res = $this->query( "SELECT current_schemas(false)", __METHOD__ );
1208                 $row = $this->fetchRow( $res );
1209                 $schemas = array();
1210
1211                 /* PHP pgsql support does not support array type, "{a,b}" string is returned */
1212
1213                 return $this->pg_array_parse( $row[0], $schemas );
1214         }
1215
1216         /**
1217          * Return search patch for schemas
1218          * This is different from getSchemas() since it contain magic keywords
1219          * (like "$user").
1220          * Needs transaction
1221          *
1222          * @since 1.19
1223          * @return array How to search for table names schemas for the current user
1224          */
1225         function getSearchPath() {
1226                 $res = $this->query( "SHOW search_path", __METHOD__ );
1227                 $row = $this->fetchRow( $res );
1228
1229                 /* PostgreSQL returns SHOW values as strings */
1230
1231                 return explode( ",", $row[0] );
1232         }
1233
1234         /**
1235          * Update search_path, values should already be sanitized
1236          * Values may contain magic keywords like "$user"
1237          * @since 1.19
1238          *
1239          * @param $search_path array list of schemas to be searched by default
1240          */
1241         function setSearchPath( $search_path ) {
1242                 $this->query( "SET search_path = " . implode( ", ", $search_path ) );
1243         }
1244
1245         /**
1246          * Determine default schema for MediaWiki core
1247          * Adjust this session schema search path if desired schema exists
1248          * and is not alread there.
1249          *
1250          * We need to have name of the core schema stored to be able
1251          * to query database metadata.
1252          *
1253          * This will be also called by the installer after the schema is created
1254          *
1255          * @since 1.19
1256          *
1257          * @param string $desiredSchema
1258          */
1259         function determineCoreSchema( $desiredSchema ) {
1260                 $this->begin( __METHOD__ );
1261                 if ( $this->schemaExists( $desiredSchema ) ) {
1262                         if ( in_array( $desiredSchema, $this->getSchemas() ) ) {
1263                                 $this->mCoreSchema = $desiredSchema;
1264                                 wfDebug( "Schema \"" . $desiredSchema . "\" already in the search path\n" );
1265                         } else {
1266                                 /**
1267                                  * Prepend our schema (e.g. 'mediawiki') in front
1268                                  * of the search path
1269                                  * Fixes bug 15816
1270                                  */
1271                                 $search_path = $this->getSearchPath();
1272                                 array_unshift( $search_path,
1273                                         $this->addIdentifierQuotes( $desiredSchema ) );
1274                                 $this->setSearchPath( $search_path );
1275                                 $this->mCoreSchema = $desiredSchema;
1276                                 wfDebug( "Schema \"" . $desiredSchema . "\" added to the search path\n" );
1277                         }
1278                 } else {
1279                         $this->mCoreSchema = $this->getCurrentSchema();
1280                         wfDebug( "Schema \"" . $desiredSchema . "\" not found, using current \"" .
1281                                 $this->mCoreSchema . "\"\n" );
1282                 }
1283                 /* Commit SET otherwise it will be rollbacked on error or IGNORE SELECT */
1284                 $this->commit( __METHOD__ );
1285         }
1286
1287         /**
1288          * Return schema name fore core MediaWiki tables
1289          *
1290          * @since 1.19
1291          * @return string core schema name
1292          */
1293         function getCoreSchema() {
1294                 return $this->mCoreSchema;
1295         }
1296
1297         /**
1298          * @return string Version information from the database
1299          */
1300         function getServerVersion() {
1301                 if ( !isset( $this->numericVersion ) ) {
1302                         $versionInfo = pg_version( $this->mConn );
1303                         if ( version_compare( $versionInfo['client'], '7.4.0', 'lt' ) ) {
1304                                 // Old client, abort install
1305                                 $this->numericVersion = '7.3 or earlier';
1306                         } elseif ( isset( $versionInfo['server'] ) ) {
1307                                 // Normal client
1308                                 $this->numericVersion = $versionInfo['server'];
1309                         } else {
1310                                 // Bug 16937: broken pgsql extension from PHP<5.3
1311                                 $this->numericVersion = pg_parameter_status( $this->mConn, 'server_version' );
1312                         }
1313                 }
1314
1315                 return $this->numericVersion;
1316         }
1317
1318         /**
1319          * Query whether a given relation exists (in the given schema, or the
1320          * default mw one if not given)
1321          * @param string $table
1322          * @param array|string $types
1323          * @param bool|string $schema
1324          * @return bool
1325          */
1326         function relationExists( $table, $types, $schema = false ) {
1327                 if ( !is_array( $types ) ) {
1328                         $types = array( $types );
1329                 }
1330                 if ( !$schema ) {
1331                         $schema = $this->getCoreSchema();
1332                 }
1333                 $table = $this->realTableName( $table, 'raw' );
1334                 $etable = $this->addQuotes( $table );
1335                 $eschema = $this->addQuotes( $schema );
1336                 $SQL = "SELECT 1 FROM pg_catalog.pg_class c, pg_catalog.pg_namespace n "
1337                         . "WHERE c.relnamespace = n.oid AND c.relname = $etable AND n.nspname = $eschema "
1338                         . "AND c.relkind IN ('" . implode( "','", $types ) . "')";
1339                 $res = $this->query( $SQL );
1340                 $count = $res ? $res->numRows() : 0;
1341
1342                 return (bool)$count;
1343         }
1344
1345         /**
1346          * For backward compatibility, this function checks both tables and
1347          * views.
1348          * @param string $table
1349          * @param string $fname
1350          * @param bool|string $schema
1351          * @return bool
1352          */
1353         function tableExists( $table, $fname = __METHOD__, $schema = false ) {
1354                 return $this->relationExists( $table, array( 'r', 'v' ), $schema );
1355         }
1356
1357         function sequenceExists( $sequence, $schema = false ) {
1358                 return $this->relationExists( $sequence, 'S', $schema );
1359         }
1360
1361         function triggerExists( $table, $trigger ) {
1362                 $q = <<<SQL
1363         SELECT 1 FROM pg_class, pg_namespace, pg_trigger
1364                 WHERE relnamespace=pg_namespace.oid AND relkind='r'
1365                           AND tgrelid=pg_class.oid
1366                           AND nspname=%s AND relname=%s AND tgname=%s
1367 SQL;
1368                 $res = $this->query(
1369                         sprintf(
1370                                 $q,
1371                                 $this->addQuotes( $this->getCoreSchema() ),
1372                                 $this->addQuotes( $table ),
1373                                 $this->addQuotes( $trigger )
1374                         )
1375                 );
1376                 if ( !$res ) {
1377                         return null;
1378                 }
1379                 $rows = $res->numRows();
1380
1381                 return $rows;
1382         }
1383
1384         function ruleExists( $table, $rule ) {
1385                 $exists = $this->selectField( 'pg_rules', 'rulename',
1386                         array(
1387                                 'rulename' => $rule,
1388                                 'tablename' => $table,
1389                                 'schemaname' => $this->getCoreSchema()
1390                         )
1391                 );
1392
1393                 return $exists === $rule;
1394         }
1395
1396         function constraintExists( $table, $constraint ) {
1397                 $SQL = sprintf( "SELECT 1 FROM information_schema.table_constraints " .
1398                         "WHERE constraint_schema = %s AND table_name = %s AND constraint_name = %s",
1399                         $this->addQuotes( $this->getCoreSchema() ),
1400                         $this->addQuotes( $table ),
1401                         $this->addQuotes( $constraint )
1402                 );
1403                 $res = $this->query( $SQL );
1404                 if ( !$res ) {
1405                         return null;
1406                 }
1407                 $rows = $res->numRows();
1408
1409                 return $rows;
1410         }
1411
1412         /**
1413          * Query whether a given schema exists. Returns true if it does, false if it doesn't.
1414          * @param string $schema
1415          * @return bool
1416          */
1417         function schemaExists( $schema ) {
1418                 $exists = $this->selectField( '"pg_catalog"."pg_namespace"', 1,
1419                         array( 'nspname' => $schema ), __METHOD__ );
1420
1421                 return (bool)$exists;
1422         }
1423
1424         /**
1425          * Returns true if a given role (i.e. user) exists, false otherwise.
1426          * @param string $roleName
1427          * @return bool
1428          */
1429         function roleExists( $roleName ) {
1430                 $exists = $this->selectField( '"pg_catalog"."pg_roles"', 1,
1431                         array( 'rolname' => $roleName ), __METHOD__ );
1432
1433                 return (bool)$exists;
1434         }
1435
1436         function fieldInfo( $table, $field ) {
1437                 return PostgresField::fromText( $this, $table, $field );
1438         }
1439
1440         /**
1441          * pg_field_type() wrapper
1442          * @param ResultWrapper|resource $res ResultWrapper or PostgreSQL query result resource
1443          * @param int $index Field number, starting from 0
1444          * @return string
1445          */
1446         function fieldType( $res, $index ) {
1447                 if ( $res instanceof ResultWrapper ) {
1448                         $res = $res->result;
1449                 }
1450
1451                 return pg_field_type( $res, $index );
1452         }
1453
1454         /**
1455          * @param string $b
1456          * @return Blob
1457          */
1458         function encodeBlob( $b ) {
1459                 return new Blob( pg_escape_bytea( $this->mConn, $b ) );
1460         }
1461
1462         function decodeBlob( $b ) {
1463                 if ( $b instanceof Blob ) {
1464                         $b = $b->fetch();
1465                 }
1466
1467                 return pg_unescape_bytea( $b );
1468         }
1469
1470         function strencode( $s ) { # Should not be called by us
1471                 return pg_escape_string( $this->mConn, $s );
1472         }
1473
1474         /**
1475          * @param null|bool|Blob $s
1476          * @return int|string
1477          */
1478         function addQuotes( $s ) {
1479                 if ( is_null( $s ) ) {
1480                         return 'NULL';
1481                 } elseif ( is_bool( $s ) ) {
1482                         return intval( $s );
1483                 } elseif ( $s instanceof Blob ) {
1484                         return "'" . $s->fetch( $s ) . "'";
1485                 }
1486
1487                 return "'" . pg_escape_string( $this->mConn, $s ) . "'";
1488         }
1489
1490         /**
1491          * Postgres specific version of replaceVars.
1492          * Calls the parent version in Database.php
1493          *
1494          * @param string $ins SQL string, read from a stream (usually tables.sql)
1495          * @return string SQL string
1496          */
1497         protected function replaceVars( $ins ) {
1498                 $ins = parent::replaceVars( $ins );
1499
1500                 if ( $this->numericVersion >= 8.3 ) {
1501                         // Thanks for not providing backwards-compatibility, 8.3
1502                         $ins = preg_replace( "/to_tsvector\s*\(\s*'default'\s*,/", 'to_tsvector(', $ins );
1503                 }
1504
1505                 if ( $this->numericVersion <= 8.1 ) { // Our minimum version
1506                         $ins = str_replace( 'USING gin', 'USING gist', $ins );
1507                 }
1508
1509                 return $ins;
1510         }
1511
1512         /**
1513          * Various select options
1514          *
1515          * @param array $options an associative array of options to be turned into
1516          *   an SQL query, valid keys are listed in the function.
1517          * @return array
1518          */
1519         function makeSelectOptions( $options ) {
1520                 $preLimitTail = $postLimitTail = '';
1521                 $startOpts = $useIndex = '';
1522
1523                 $noKeyOptions = array();
1524                 foreach ( $options as $key => $option ) {
1525                         if ( is_numeric( $key ) ) {
1526                                 $noKeyOptions[$option] = true;
1527                         }
1528                 }
1529
1530                 $preLimitTail .= $this->makeGroupByWithHaving( $options );
1531
1532                 $preLimitTail .= $this->makeOrderBy( $options );
1533
1534                 //if ( isset( $options['LIMIT'] ) ) {
1535                 //      $tailOpts .= $this->limitResult( '', $options['LIMIT'],
1536                 //              isset( $options['OFFSET'] ) ? $options['OFFSET']
1537                 //              : false );
1538                 //}
1539
1540                 if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
1541                         $postLimitTail .= ' FOR UPDATE';
1542                 }
1543                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1544                         $startOpts .= 'DISTINCT';
1545                 }
1546
1547                 return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
1548         }
1549
1550         function setFakeMaster( $enabled = true ) {
1551         }
1552
1553         function getDBname() {
1554                 return $this->mDBname;
1555         }
1556
1557         function getServer() {
1558                 return $this->mServer;
1559         }
1560
1561         function buildConcat( $stringList ) {
1562                 return implode( ' || ', $stringList );
1563         }
1564
1565         public function buildGroupConcatField(
1566                 $delimiter, $table, $field, $conds = '', $options = array(), $join_conds = array()
1567         ) {
1568                 $fld = "array_to_string(array_agg($field)," . $this->addQuotes( $delimiter ) . ')';
1569
1570                 return '(' . $this->selectSQLText( $table, $fld, $conds, null, array(), $join_conds ) . ')';
1571         }
1572
1573         public function getSearchEngine() {
1574                 return 'SearchPostgres';
1575         }
1576
1577         public function streamStatementEnd( &$sql, &$newLine ) {
1578                 # Allow dollar quoting for function declarations
1579                 if ( substr( $newLine, 0, 4 ) == '$mw$' ) {
1580                         if ( $this->delimiter ) {
1581                                 $this->delimiter = false;
1582                         } else {
1583                                 $this->delimiter = ';';
1584                         }
1585                 }
1586
1587                 return parent::streamStatementEnd( $sql, $newLine );
1588         }
1589
1590         /**
1591          * Check to see if a named lock is available. This is non-blocking.
1592          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1593          *
1594          * @param string $lockName Name of lock to poll
1595          * @param string $method Name of method calling us
1596          * @return bool
1597          * @since 1.20
1598          */
1599         public function lockIsFree( $lockName, $method ) {
1600                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1601                 $result = $this->query( "SELECT (CASE(pg_try_advisory_lock($key))
1602                         WHEN 'f' THEN 'f' ELSE pg_advisory_unlock($key) END) AS lockstatus", $method );
1603                 $row = $this->fetchObject( $result );
1604
1605                 return ( $row->lockstatus === 't' );
1606         }
1607
1608         /**
1609          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1610          * @param string $lockName
1611          * @param string $method
1612          * @param int $timeout
1613          * @return bool
1614          */
1615         public function lock( $lockName, $method, $timeout = 5 ) {
1616                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1617                 for ( $attempts = 1; $attempts <= $timeout; ++$attempts ) {
1618                         $result = $this->query(
1619                                 "SELECT pg_try_advisory_lock($key) AS lockstatus", $method );
1620                         $row = $this->fetchObject( $result );
1621                         if ( $row->lockstatus === 't' ) {
1622                                 return true;
1623                         } else {
1624                                 sleep( 1 );
1625                         }
1626                 }
1627                 wfDebug( __METHOD__ . " failed to acquire lock\n" );
1628
1629                 return false;
1630         }
1631
1632         /**
1633          * See http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKSFROM
1634          * PG DOCS: http://www.postgresql.org/docs/8.2/static/functions-admin.html#FUNCTIONS-ADVISORY-LOCKS
1635          * @param string $lockName
1636          * @param string $method
1637          * @return bool
1638          */
1639         public function unlock( $lockName, $method ) {
1640                 $key = $this->addQuotes( $this->bigintFromLockName( $lockName ) );
1641                 $result = $this->query( "SELECT pg_advisory_unlock($key) as lockstatus", $method );
1642                 $row = $this->fetchObject( $result );
1643
1644                 return ( $row->lockstatus === 't' );
1645         }
1646
1647         /**
1648          * @param string $lockName
1649          * @return string Integer
1650          */
1651         private function bigintFromLockName( $lockName ) {
1652                 return wfBaseConvert( substr( sha1( $lockName ), 0, 15 ), 16, 10 );
1653         }
1654 } // end DatabasePostgres class