includes/db/DatabaseIbm_db2.php

   1 <?php
   2 /**
   3  * This script is the IBM DB2 database abstraction layer
   4  *
   5  * See maintenance/ibm_db2/README for development notes and other specific information
   6  * @ingroup Database
   7  * @file
   8  * @author leo.petr+mediawiki@gmail.com
   9  */
  10
  11 /**
  12  * Utility class for generating blank objects
  13  * Intended as an equivalent to {} in Javascript
  14  * @ingroup Database
  15  */
  16 class BlankObject {
  17 }
  18
  19
  20 /**
  21  * This represents a column in a DB2 database
  22  * @ingroup Database
  23  */
  24 class IBM_DB2Field {
  25         private $name = '';
  26         private $tablename = '';
  27         private $type = '';
  28         private $nullable = false;
  29         private $max_length = 0;
  30
  31         /**
  32          * Builder method for the class
  33          * @param DatabaseIbm_db2 $db Database interface
  34          * @param string $table table name
  35          * @param string $field column name
  36          * @return IBM_DB2Field
  37          */
  38         static function fromText($db, $table, $field) {
  39                 global $wgDBmwschema;
  40
  41                 $q = <<<END
  42 SELECT
  43 lcase(coltype) AS typname,
  44 nulls AS attnotnull, length AS attlen
  45 FROM sysibm.syscolumns
  46 WHERE tbcreator=%s AND tbname=%s AND name=%s;
  47 END;
  48                 $res = $db->query(sprintf($q,
  49                                 $db->addQuotes($wgDBmwschema),
  50                                 $db->addQuotes($table),
  51                                 $db->addQuotes($field)));
  52                 $row = $db->fetchObject($res);
  53                 if (!$row)
  54                         return null;
  55                 $n = new IBM_DB2Field;
  56                 $n->type = $row->typname;
  57                 $n->nullable = ($row->attnotnull == 'N');
  58                 $n->name = $field;
  59                 $n->tablename = $table;
  60                 $n->max_length = $row->attlen;
  61                 return $n;
  62         }
  63         /**
  64          * Get column name
  65          * @return string column name
  66          */
  67         function name() { return $this->name; }
  68         /**
  69          * Get table name
  70          * @return string table name
  71          */
  72         function tableName() { return $this->tablename; }
  73         /**
  74          * Get column type
  75          * @return string column type
  76          */
  77         function type() { return $this->type; }
  78         /**
  79          * Can column be null?
  80          * @return bool true or false
  81          */
  82         function nullable() { return $this->nullable; }
  83         /**
  84          * How much can you fit in the column per row?
  85          * @return int length
  86          */
  87         function maxLength() { return $this->max_length; }
  88 }
  89
  90 /**
  91  * Wrapper around binary large objects
  92  * @ingroup Database
  93  */
  94 class IBM_DB2Blob {
  95         private $mData;
  96
  97         function __construct($data) {
  98                 $this->mData = $data;
  99         }
 100
 101         function getData() {
 102                 return $this->mData;
 103         }
 104 }
 105
 106 /**
 107  * Primary database interface
 108  * @ingroup Database
 109  */
 110 class DatabaseIbm_db2 extends DatabaseBase {
 111         /*
 112          * Inherited members
 113         protected $mLastQuery = '';
 114         protected $mPHPError = false;
 115
 116         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 117         protected $mOut, $mOpened = false;
 118
 119         protected $mFailFunction;
 120         protected $mTablePrefix;
 121         protected $mFlags;
 122         protected $mTrxLevel = 0;
 123         protected $mErrorCount = 0;
 124         protected $mLBInfo = array();
 125         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 126          *
 127          */
 128
 129         /// Server port for uncataloged connections
 130         protected $mPort = NULL;
 131         /// Whether connection is cataloged
 132         protected $mCataloged = NULL;
 133         /// Schema for tables, stored procedures, triggers
 134         protected $mSchema = NULL;
 135         /// Whether the schema has been applied in this session
 136         protected $mSchemaSet = false;
 137         /// Result of last query
 138         protected $mLastResult = NULL;
 139         /// Number of rows affected by last INSERT/UPDATE/DELETE
 140         protected $mAffectedRows = NULL;
 141         /// Number of rows returned by last SELECT
 142         protected $mNumRows = NULL;
 143
 144         /// Connection config options - see constructor
 145         public $mConnOptions = array();
 146         /// Statement config options -- see constructor
 147         public $mStmtOptions = array();
 148
 149
 150         const CATALOGED = "cataloged";
 151         const UNCATALOGED = "uncataloged";
 152         const USE_GLOBAL = "get from global";
 153
 154         const NONE_OPTION = 0x00;
 155         const CONN_OPTION = 0x01;
 156         const STMT_OPTION = 0x02;
 157
 158         const REGULAR_MODE = 'regular';
 159         const INSTALL_MODE = 'install';
 160
 161         // Whether this is regular operation or the initial installation
 162         protected $mMode = self::REGULAR_MODE;
 163
 164         /// Last sequence value used for a primary key
 165         protected $mInsertId = NULL;
 166
 167         /*
 168          * These can be safely inherited
 169          *
 170          * Getter/Setter: (18)
 171          * failFunction
 172          * setOutputPage
 173          * bufferResults
 174          * ignoreErrors
 175          * trxLevel
 176          * errorCount
 177          * getLBInfo
 178          * setLBInfo
 179          * lastQuery
 180          * isOpen
 181          * setFlag
 182          * clearFlag
 183          * getFlag
 184          * getProperty
 185          * getDBname
 186          * getServer
 187          * tableNameCallback
 188          * tablePrefix
 189          *
 190          * Administrative: (8)
 191          * debug
 192          * installErrorHandler
 193          * restoreErrorHandler
 194          * connectionErrorHandler
 195          * reportConnectionError
 196          * sourceFile
 197          * sourceStream
 198          * replaceVars
 199          *
 200          * Database: (5)
 201          * query
 202          * set
 203          * selectField
 204          * generalizeSQL
 205          * update
 206          * strreplace
 207          * deadlockLoop
 208          *
 209          * Prepared Statement: 6
 210          * prepare
 211          * freePrepared
 212          * execute
 213          * safeQuery
 214          * fillPrepared
 215          * fillPreparedArg
 216          *
 217          * Slave/Master: (4)
 218          * masterPosWait
 219          * getSlavePos
 220          * getMasterPos
 221          * getLag
 222          *
 223          * Generation: (9)
 224          * tableNames
 225          * tableNamesN
 226          * tableNamesWithUseIndexOrJOIN
 227          * escapeLike
 228          * delete
 229          * insertSelect
 230          * timestampOrNull
 231          * resultObject
 232          * aggregateValue
 233          * selectSQLText
 234          * selectRow
 235          * makeUpdateOptions
 236          *
 237          * Reflection: (1)
 238          * indexExists
 239          */
 240
 241         /*
 242          * These have been implemented
 243          *
 244          * Administrative: 7 / 7
 245          * constructor [Done]
 246          * open [Done]
 247          * openCataloged [Done]
 248          * close [Done]
 249          * newFromParams [Done]
 250          * openUncataloged [Done]
 251          * setup_database [Done]
 252          *
 253          * Getter/Setter: 13 / 13
 254          * cascadingDeletes [Done]
 255          * cleanupTriggers  [Done]
 256          * strictIPs  [Done]
 257          * realTimestamps  [Done]
 258          * impliciGroupby  [Done]
 259          * implicitOrderby  [Done]
 260          * searchableIPs  [Done]
 261          * functionalIndexes  [Done]
 262          * getWikiID  [Done]
 263          * isOpen [Done]
 264          * getServerVersion [Done]
 265          * getSoftwareLink [Done]
 266          * getSearchEngine [Done]
 267          *
 268          * Database driver wrapper: 23 / 23
 269          * lastError [Done]
 270          * lastErrno [Done]
 271          * doQuery [Done]
 272          * tableExists [Done]
 273          * fetchObject [Done]
 274          * fetchRow [Done]
 275          * freeResult [Done]
 276          * numRows [Done]
 277          * numFields [Done]
 278          * fieldName [Done]
 279          * insertId [Done]
 280          * dataSeek [Done]
 281          * affectedRows [Done]
 282          * selectDB [Done]
 283          * strencode [Done]
 284          * conditional [Done]
 285          * wasDeadlock [Done]
 286          * ping [Done]
 287          * getStatus [Done]
 288          * setTimeout [Done]
 289          * lock [Done]
 290          * unlock [Done]
 291          * insert [Done]
 292          * select [Done]
 293          *
 294          * Slave/master: 2 / 2
 295          * setFakeSlaveLag [Done]
 296          * setFakeMaster [Done]
 297          *
 298          * Reflection: 6 / 6
 299          * fieldExists [Done]
 300          * indexInfo [Done]
 301          * fieldInfo [Done]
 302          * fieldType [Done]
 303          * indexUnique [Done]
 304          * textFieldSize [Done]
 305          *
 306          * Generation: 16 / 16
 307          * tableName [Done]
 308          * addQuotes [Done]
 309          * makeList [Done]
 310          * makeSelectOptions [Done]
 311          * estimateRowCount [Done]
 312          * nextSequenceValue [Done]
 313          * useIndexClause [Done]
 314          * replace [Done]
 315          * deleteJoin [Done]
 316          * lowPriorityOption [Done]
 317          * limitResult [Done]
 318          * limitResultForUpdate [Done]
 319          * timestamp [Done]
 320          * encodeBlob [Done]
 321          * decodeBlob [Done]
 322          * buildConcat [Done]
 323          */
 324
 325         ######################################
 326         # Getters and Setters
 327         ######################################
 328
 329         /**
 330          * Returns true if this database supports (and uses) cascading deletes
 331          */
 332         function cascadingDeletes() {
 333                 return true;
 334         }
 335
 336         /**
 337          * Returns true if this database supports (and uses) triggers (e.g. on the page table)
 338          */
 339         function cleanupTriggers() {
 340                 return true;
 341         }
 342
 343         /**
 344          * Returns true if this database is strict about what can be put into an IP field.
 345          * Specifically, it uses a NULL value instead of an empty string.
 346          */
 347         function strictIPs() {
 348                 return true;
 349         }
 350
 351         /**
 352          * Returns true if this database uses timestamps rather than integers
 353         */
 354         function realTimestamps() {
 355                 return true;
 356         }
 357
 358         /**
 359          * Returns true if this database does an implicit sort when doing GROUP BY
 360          */
 361         function implicitGroupby() {
 362                 return false;
 363         }
 364
 365         /**
 366          * Returns true if this database does an implicit order by when the column has an index
 367          * For example: SELECT page_title FROM page LIMIT 1
 368          */
 369         function implicitOrderby() {
 370                 return false;
 371         }
 372
 373         /**
 374          * Returns true if this database can do a native search on IP columns
 375          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 376          */
 377         function searchableIPs() {
 378                 return true;
 379         }
 380
 381         /**
 382          * Returns true if this database can use functional indexes
 383          */
 384         function functionalIndexes() {
 385                 return true;
 386         }
 387
 388         /**
 389          * Returns a unique string representing the wiki on the server
 390          */
 391         function getWikiID() {
 392                 if( $this->mSchema ) {
 393                         return "{$this->mDBname}-{$this->mSchema}";
 394                 } else {
 395                         return $this->mDBname;
 396                 }
 397         }
 398
 399
 400         ######################################
 401         # Setup
 402         ######################################
 403
 404
 405         /**
 406          *
 407          * @param string $server hostname of database server
 408          * @param string $user username
 409          * @param string $password
 410          * @param string $dbName database name on the server
 411          * @param function $failFunction (optional)
 412          * @param integer $flags database behaviour flags (optional, unused)
 413          */
 414         public function DatabaseIbm_db2($server = false, $user = false, $password = false,
 415                                                         $dbName = false, $failFunction = false, $flags = 0,
 416                                                         $schema = self::USE_GLOBAL )
 417         {
 418
 419                 global $wgOut, $wgDBmwschema;
 420                 # Can't get a reference if it hasn't been set yet
 421                 if ( !isset( $wgOut ) ) {
 422                         $wgOut = NULL;
 423                 }
 424                 $this->mOut =& $wgOut;
 425                 $this->mFailFunction = $failFunction;
 426                 $this->mFlags = DBO_TRX | $flags;
 427
 428                 if ( $schema == self::USE_GLOBAL ) {
 429                         $this->mSchema = $wgDBmwschema;
 430                 }
 431                 else {
 432                         $this->mSchema = $schema;
 433                 }
 434
 435                 // configure the connection and statement objects
 436                 $this->setDB2Option('db2_attr_case', 'DB2_CASE_LOWER', self::CONN_OPTION | self::STMT_OPTION);
 437                 $this->setDB2Option('deferred_prepare', 'DB2_DEFERRED_PREPARE_ON', self::STMT_OPTION);
 438                 $this->setDB2Option('rowcount', 'DB2_ROWCOUNT_PREFETCH_ON', self::STMT_OPTION);
 439
 440                 $this->open( $server, $user, $password, $dbName);
 441         }
 442
 443         /**
 444          * Enables options only if the ibm_db2 extension version supports them
 445          * @param string $name Name of the option in the options array
 446          * @param string $const Name of the constant holding the right option value
 447          * @param int $type Whether this is a Connection or Statement otion
 448          */
 449         private function setDB2Option($name, $const, $type) {
 450                 if (defined($const)) {
 451                         if ($type & self::CONN_OPTION) $this->mConnOptions[$name] = constant($const);
 452                         if ($type & self::STMT_OPTION) $this->mStmtOptions[$name] = constant($const);
 453                 }
 454                 else {
 455                         $this->installPrint("$const is not defined. ibm_db2 version is likely too low.");
 456                 }
 457         }
 458
 459         /**
 460          * Outputs debug information in the appropriate place
 461          * @param string $string The relevant debug message
 462          */
 463         private function installPrint($string) {
 464                 wfDebug("$string");
 465                 if ($this->mMode == self::INSTALL_MODE) {
 466                         print "<li>$string</li>";
 467                         flush();
 468                 }
 469         }
 470
 471         /**
 472          * Opens a database connection and returns it
 473          * Closes any existing connection
 474          * @return a fresh connection
 475          * @param string $server hostname
 476          * @param string $user
 477          * @param string $password
 478          * @param string $dbName database name
 479          */
 480         public function open( $server, $user, $password, $dbName )
 481         {
 482                 // Load the port number
 483                 global $wgDBport_db2, $wgDBcataloged;
 484                 wfProfileIn( __METHOD__ );
 485
 486                 // Load IBM DB2 driver if missing
 487                 if (!@extension_loaded('ibm_db2')) {
 488                         @dl('ibm_db2.so');
 489                 }
 490                 // Test for IBM DB2 support, to avoid suppressed fatal error
 491                 if ( !function_exists( 'db2_connect' ) ) {
 492                         $error = "DB2 functions missing, have you enabled the ibm_db2 extension for PHP?\n";
 493                         $this->installPrint($error);
 494                         $this->reportConnectionError($error);
 495                 }
 496
 497                 if (!strlen($user)) { // Copied from Postgres
 498                         return null;
 499                 }
 500
 501                 // Close existing connection
 502                 $this->close();
 503                 // Cache conn info
 504                 $this->mServer = $server;
 505                 $this->mPort = $port = $wgDBport_db2;
 506                 $this->mUser = $user;
 507                 $this->mPassword = $password;
 508                 $this->mDBname = $dbName;
 509                 $this->mCataloged = $cataloged = $wgDBcataloged;
 510
 511                 if ( $cataloged == self::CATALOGED ) {
 512                         $this->openCataloged($dbName, $user, $password);
 513                 }
 514                 elseif ( $cataloged == self::UNCATALOGED ) {
 515                         $this->openUncataloged($dbName, $user, $password, $server, $port);
 516                 }
 517                 // Apply connection config
 518                 db2_set_option($this->mConn, $this->mConnOptions, 1);
 519                 // Not all MediaWiki code is transactional
 520                 // Rather, turn autocommit off in the begin function and turn on after a commit
 521                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 522
 523                 if ( $this->mConn == false ) {
 524                         $this->installPrint( "DB connection error\n" );
 525                         $this->installPrint( "Server: $server, Database: $dbName, User: $user, Password: " . substr( $password, 0, 3 ) . "...\n" );
 526                         $this->installPrint( $this->lastError()."\n" );
 527                         return null;
 528                 }
 529
 530                 $this->mOpened = true;
 531                 $this->applySchema();
 532
 533                 wfProfileOut( __METHOD__ );
 534                 return $this->mConn;
 535         }
 536
 537         /**
 538          * Opens a cataloged database connection, sets mConn
 539          */
 540         protected function openCataloged( $dbName, $user, $password )
 541         {
 542                 @$this->mConn = db2_connect($dbName, $user, $password);
 543         }
 544
 545         /**
 546          * Opens an uncataloged database connection, sets mConn
 547          */
 548         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 549         {
 550                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 551                 $str .= "DATABASE=$dbName;";
 552                 $str .= "HOSTNAME=$server;";
 553                 if ($port) $str .= "PORT=$port;";
 554                 $str .= "PROTOCOL=TCPIP;";
 555                 $str .= "UID=$user;";
 556                 $str .= "PWD=$password;";
 557
 558                 @$this->mConn = db2_connect($str, $user, $password);
 559         }
 560
 561         /**
 562          * Closes a database connection, if it is open
 563          * Returns success, true if already closed
 564          */
 565         public function close() {
 566                 $this->mOpened = false;
 567                 if ( $this->mConn ) {
 568                         if ($this->trxLevel() > 0) {
 569                                 $this->commit();
 570                         }
 571                         return db2_close( $this->mConn );
 572                 }
 573                 else {
 574                         return true;
 575                 }
 576         }
 577
 578         /**
 579          * Returns a fresh instance of this class
 580          * @static
 581          * @return
 582          * @param string $server hostname of database server
 583          * @param string $user username
 584          * @param string $password
 585          * @param string $dbName database name on the server
 586          * @param function $failFunction (optional)
 587          * @param integer $flags database behaviour flags (optional, unused)
 588          */
 589         static function newFromParams( $server, $user, $password, $dbName, $failFunction = false, $flags = 0)
 590         {
 591                 return new DatabaseIbm_db2( $server, $user, $password, $dbName, $failFunction, $flags );
 592         }
 593
 594         /**
 595          * Retrieves the most current database error
 596          * Forces a database rollback
 597          */
 598         public function lastError() {
 599                 $connerr = db2_conn_errormsg();
 600                 if ($connerr) {
 601                         //$this->rollback();
 602                         return $connerr;
 603                 }
 604                 $stmterr = db2_stmt_errormsg();
 605                 if ($stmterr) {
 606                         //$this->rollback();
 607                         return $stmterr;
 608                 }
 609
 610                 return false;
 611         }
 612
 613         /**
 614          * Get the last error number
 615          * Return 0 if no error
 616          * @return integer
 617          */
 618         public function lastErrno() {
 619                 $connerr = db2_conn_error();
 620                 if ($connerr) return $connerr;
 621                 $stmterr = db2_stmt_error();
 622                 if ($stmterr) return $stmterr;
 623                 return 0;
 624         }
 625
 626         /**
 627          * Is a database connection open?
 628          * @return
 629          */
 630         public function isOpen() { return $this->mOpened; }
 631
 632         /**
 633          * The DBMS-dependent part of query()
 634          * @param  $sql String: SQL query.
 635          * @return object Result object to feed to fetchObject, fetchRow, ...; or false on failure
 636          * @access private
 637          */
 638         /*private*/
 639         public function doQuery( $sql ) {
 640                 //print "<li><pre>$sql</pre></li>";
 641                 // Switch into the correct namespace
 642                 $this->applySchema();
 643
 644                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 645                 if( !$ret ) {
 646                         print "<br><pre>";
 647                         print $sql;
 648                         print "</pre><br>";
 649                         $error = db2_stmt_errormsg();
 650                         throw new DBUnexpectedError($this,  'SQL error: ' . htmlspecialchars( $error ) );
 651                 }
 652                 $this->mLastResult = $ret;
 653                 $this->mAffectedRows = NULL;    // Not calculated until asked for
 654                 return $ret;
 655         }
 656
 657         /**
 658          * @return string Version information from the database
 659          */
 660         public function getServerVersion() {
 661                 $info = db2_server_info( $this->mConn );
 662                 return $info->DBMS_VER;
 663         }
 664
 665         /**
 666          * Queries whether a given table exists
 667          * @return boolean
 668          */
 669         public function tableExists( $table ) {
 670                 $schema = $this->mSchema;
 671                 $sql = <<< EOF
 672 SELECT COUNT(*) FROM SYSIBM.SYSTABLES ST
 673 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 674 EOF;
 675                 $res = $this->query( $sql );
 676                 if (!$res) return false;
 677
 678                 // If the table exists, there should be one of it
 679                 @$row = $this->fetchRow($res);
 680                 $count = $row[0];
 681                 if ($count == '1' or $count == 1) {
 682                         return true;
 683                 }
 684
 685                 return false;
 686         }
 687
 688         /**
 689          * Fetch the next row from the given result object, in object form.
 690          * Fields can be retrieved with $row->fieldname, with fields acting like
 691          * member variables.
 692          *
 693          * @param $res SQL result object as returned from Database::query(), etc.
 694          * @return DB2 row object
 695          * @throws DBUnexpectedError Thrown if the database returns an error
 696          */
 697         public function fetchObject( $res ) {
 698                 if ( $res instanceof ResultWrapper ) {
 699                         $res = $res->result;
 700                 }
 701                 @$row = db2_fetch_object( $res );
 702                 if( $this->lastErrno() ) {
 703                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): ' . htmlspecialchars( $this->lastError() ) );
 704                 }
 705                 // Make field names lowercase for compatibility with MySQL
 706                 if ($row)
 707                 {
 708                         $row2 = new BlankObject();
 709                         foreach ($row as $key => $value)
 710                         {
 711                                 $keyu = strtolower($key);
 712                                 $row2->$keyu = $value;
 713                         }
 714                         $row = $row2;
 715                 }
 716                 return $row;
 717         }
 718
 719         /**
 720          * Fetch the next row from the given result object, in associative array
 721          * form.  Fields are retrieved with $row['fieldname'].
 722          *
 723          * @param $res SQL result object as returned from Database::query(), etc.
 724          * @return DB2 row object
 725          * @throws DBUnexpectedError Thrown if the database returns an error
 726          */
 727         public function fetchRow( $res ) {
 728                 if ( $res instanceof ResultWrapper ) {
 729                         $res = $res->result;
 730                 }
 731                 @$row = db2_fetch_array( $res );
 732                 if ( $this->lastErrno() ) {
 733                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): ' . htmlspecialchars( $this->lastError() ) );
 734                 }
 735                 return $row;
 736         }
 737
 738         /**
 739          * Override if introduced to base Database class
 740          */
 741         public function initial_setup() {
 742                 // do nothing
 743         }
 744
 745         /**
 746          * Create tables, stored procedures, and so on
 747          */
 748         public function setup_database() {
 749                 // Timeout was being changed earlier due to mysterious crashes
 750                 // Changing it now may cause more problems than not changing it
 751                 //set_time_limit(240);
 752                 try {
 753                         // TODO: switch to root login if available
 754
 755                         // Switch into the correct namespace
 756                         $this->applySchema();
 757                         $this->begin();
 758
 759                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 760                         $res = null;
 761
 762                         // TODO: update mediawiki_version table
 763
 764                         // TODO: populate interwiki links
 765
 766                         if ($this->lastError()) {
 767                                 print "<li>Errors encountered during table creation -- rolled back</li>\n";
 768                                 print "<li>Please install again</li>\n";
 769                                 $this->rollback();
 770                         }
 771                         else {
 772                                 $this->commit();
 773                         }
 774                 }
 775                 catch (MWException $mwe)
 776                 {
 777                         print "<br><pre>$mwe</pre><br>";
 778                 }
 779         }
 780
 781         /**
 782          * Escapes strings
 783          * Doesn't escape numbers
 784          * @param string s string to escape
 785          * @return escaped string
 786          */
 787         public function addQuotes( $s ) {
 788                 //$this->installPrint("DB2::addQuotes($s)\n");
 789                 if ( is_null( $s ) ) {
 790                         return "NULL";
 791                 } else if ($s instanceof Blob) {
 792                         return "'".$s->fetch($s)."'";
 793                 }
 794                 $s = $this->strencode($s);
 795                 if ( is_numeric($s) ) {
 796                         return $s;
 797                 }
 798                 else {
 799                         return "'$s'";
 800                 }
 801         }
 802
 803         /**
 804          * Verifies that a DB2 column/field type is numeric
 805          * @return bool true if numeric
 806          * @param string $type DB2 column type
 807          */
 808         public function is_numeric_type( $type ) {
 809                 switch (strtoupper($type)) {
 810                 case 'SMALLINT':
 811                 case 'INTEGER':
 812                 case 'INT':
 813                 case 'BIGINT':
 814                 case 'DECIMAL':
 815                 case 'REAL':
 816                 case 'DOUBLE':
 817                 case 'DECFLOAT':
 818                         return true;
 819                 }
 820                 return false;
 821         }
 822
 823         /**
 824          * Alias for addQuotes()
 825          * @param string s string to escape
 826          * @return escaped string
 827          */
 828         public function strencode( $s ) {
 829                 // Bloody useless function
 830                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 831                 //  But also necessary
 832                 $s = db2_escape_string($s);
 833                 // Wide characters are evil -- some of them look like '
 834                 $s = utf8_encode($s);
 835                 // Fix its stupidity
 836                 $from = array("\\\\",   "\\'",  '\\n',  '\\t',  '\\"',  '\\r');
 837                 $to =   array("\\",             "''",   "\n",   "\t",   '"',    "\r");
 838                 $s = str_replace($from, $to, $s); // DB2 expects '', not \' escaping
 839                 return $s;
 840         }
 841
 842         /**
 843          * Switch into the database schema
 844          */
 845         protected function applySchema() {
 846                 if ( !($this->mSchemaSet) ) {
 847                         $this->mSchemaSet = true;
 848                         $this->begin();
 849                         $this->doQuery("SET SCHEMA = $this->mSchema");
 850                         $this->commit();
 851                 }
 852         }
 853
 854         /**
 855          * Start a transaction (mandatory)
 856          */
 857         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 858                 // turn off auto-commit
 859                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_OFF);
 860                 $this->mTrxLevel = 1;
 861         }
 862
 863         /**
 864          * End a transaction
 865          * Must have a preceding begin()
 866          */
 867         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 868                 db2_commit($this->mConn);
 869                 // turn auto-commit back on
 870                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 871                 $this->mTrxLevel = 0;
 872         }
 873
 874         /**
 875          * Cancel a transaction
 876          */
 877         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 878                 db2_rollback($this->mConn);
 879                 // turn auto-commit back on
 880                 // not sure if this is appropriate
 881                 db2_autocommit($this->mConn, DB2_AUTOCOMMIT_ON);
 882                 $this->mTrxLevel = 0;
 883         }
 884
 885         /**
 886          * Makes an encoded list of strings from an array
 887          * $mode:
 888          *        LIST_COMMA         - comma separated, no field names
 889          *        LIST_AND           - ANDed WHERE clause (without the WHERE)
 890          *        LIST_OR            - ORed WHERE clause (without the WHERE)
 891          *        LIST_SET           - comma separated with field names, like a SET clause
 892          *        LIST_NAMES         - comma separated field names
 893          */
 894         public function makeList( $a, $mode = LIST_COMMA ) {
 895                 $this->installPrint("DB2::makeList()\n");
 896                 if ( !is_array( $a ) ) {
 897                         throw new DBUnexpectedError( $this, 'Database::makeList called with incorrect parameters' );
 898                 }
 899
 900                 $first = true;
 901                 $list = '';
 902                 foreach ( $a as $field => $value ) {
 903                         if ( !$first ) {
 904                                 if ( $mode == LIST_AND ) {
 905                                         $list .= ' AND ';
 906                                 } elseif($mode == LIST_OR) {
 907                                         $list .= ' OR ';
 908                                 } else {
 909                                         $list .= ',';
 910                                 }
 911                         } else {
 912                                 $first = false;
 913                         }
 914                         if ( ($mode == LIST_AND || $mode == LIST_OR) && is_numeric( $field ) ) {
 915                                 $list .= "($value)";
 916                         } elseif ( ($mode == LIST_SET) && is_numeric( $field ) ) {
 917                                 $list .= "$value";
 918                         } elseif ( ($mode == LIST_AND || $mode == LIST_OR) && is_array($value) ) {
 919                                 if( count( $value ) == 0 ) {
 920                                         throw new MWException( __METHOD__.': empty input' );
 921                                 } elseif( count( $value ) == 1 ) {
 922                                         // Special-case single values, as IN isn't terribly efficient
 923                                         // Don't necessarily assume the single key is 0; we don't
 924                                         // enforce linear numeric ordering on other arrays here.
 925                                         $value = array_values( $value );
 926                                         $list .= $field." = ".$this->addQuotes( $value[0] );
 927                                 } else {
 928                                         $list .= $field." IN (".$this->makeList($value).") ";
 929                                 }
 930                         } elseif( is_null($value) ) {
 931                                 if ( $mode == LIST_AND || $mode == LIST_OR ) {
 932                                         $list .= "$field IS ";
 933                                 } elseif ( $mode == LIST_SET ) {
 934                                         $list .= "$field = ";
 935                                 }
 936                                 $list .= 'NULL';
 937                         } else {
 938                                 if ( $mode == LIST_AND || $mode == LIST_OR || $mode == LIST_SET ) {
 939                                         $list .= "$field = ";
 940                                 }
 941                                 if ( $mode == LIST_NAMES ) {
 942                                         $list .= $value;
 943                                 }
 944                                 // Leo: Can't insert quoted numbers into numeric columns
 945                                 // (?) Might cause other problems. May have to check column type before insertion.
 946                                 else if ( is_numeric($value) ) {
 947                                         $list .= $value;
 948                                 }
 949                                 else {
 950                                         $list .= $this->addQuotes( $value );
 951                                 }
 952                         }
 953                 }
 954                 return $list;
 955         }
 956
 957         /**
 958          * Construct a LIMIT query with optional offset
 959          * This is used for query pages
 960          * $sql string SQL query we will append the limit too
 961          * $limit integer the SQL limit
 962          * $offset integer the SQL offset (default false)
 963          */
 964         public function limitResult($sql, $limit, $offset=false) {
 965                 if( !is_numeric($limit) ) {
 966                         throw new DBUnexpectedError( $this, "Invalid non-numeric limit passed to limitResult()\n" );
 967                 }
 968                 if( $offset ) {
 969                         $this->installPrint("Offset parameter not supported in limitResult()\n");
 970                 }
 971                 // TODO implement proper offset handling
 972                 // idea: get all the rows between 0 and offset, advance cursor to offset
 973                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 974         }
 975
 976         /**
 977          * Handle reserved keyword replacement in table names
 978          * @return
 979          * @param $name Object
 980          */
 981         public function tableName( $name ) {
 982                 # Replace reserved words with better ones
 983 //              switch( $name ) {
 984 //                      case 'user':
 985 //                              return 'mwuser';
 986 //                      case 'text':
 987 //                              return 'pagecontent';
 988 //                      default:
 989 //                              return $name;
 990 //              }
 991                 // we want maximum compatibility with MySQL schema
 992                 return $name;
 993         }
 994
 995         /**
 996          * Generates a timestamp in an insertable format
 997          * @return string timestamp value
 998          * @param timestamp $ts
 999          */
1000         public function timestamp( $ts=0 ) {
1001                 // TS_MW cannot be easily distinguished from an integer
1002                 return wfTimestamp(TS_DB2,$ts);
1003         }
1004
1005         /**
1006          * Return the next in a sequence, save the value for retrieval via insertId()
1007          * @param string seqName Name of a defined sequence in the database
1008          * @return next value in that sequence
1009          */
1010         public function nextSequenceValue( $seqName ) {
1011                 // Not using sequences in the primary schema to allow for easy third-party migration scripts
1012                 // Emulating MySQL behaviour of using NULL to signal that sequences aren't used
1013                 /*
1014                 $safeseq = preg_replace( "/'/", "''", $seqName );
1015                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
1016                 $row = $this->fetchRow( $res );
1017                 $this->mInsertId = $row[0];
1018                 $this->freeResult( $res );
1019                 return $this->mInsertId;
1020                 */
1021                 return NULL;
1022         }
1023
1024         /**
1025          * This must be called after nextSequenceVal
1026          * @return Last sequence value used as a primary key
1027          */
1028         public function insertId() {
1029                 return $this->mInsertId;
1030         }
1031
1032         /**
1033          * INSERT wrapper, inserts an array into a table
1034          *
1035          * $args may be a single associative array, or an array of these with numeric keys,
1036          * for multi-row insert
1037          *
1038          * @param array $table   String: Name of the table to insert to.
1039          * @param array $args    Array: Items to insert into the table.
1040          * @param array $fname   String: Name of the function, for profiling
1041          * @param mixed $options String or Array. Valid options: IGNORE
1042          *
1043          * @return bool Success of insert operation. IGNORE always returns true.
1044          */
1045         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert', $options = array() ) {
1046                 $this->installPrint("DB2::insert($table)\n");
1047                 if ( !count( $args ) ) {
1048                         return true;
1049                 }
1050                 // get database-specific table name (not used)
1051                 $table = $this->tableName( $table );
1052                 // format options as an array
1053                 if ( !is_array( $options ) ) $options = array( $options );
1054                 // format args as an array of arrays
1055                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
1056                         $args = array($args);
1057                 }
1058                 // prevent insertion of NULL into primary key columns
1059                 $args = $this->removeNullPrimaryKeys($table, $args);
1060
1061                 // get column names
1062                 $keys = array_keys( $args[0] );
1063                 $key_count = count($keys);
1064
1065                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
1066                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
1067
1068                 // If we are not in a transaction, we need to be for savepoint trickery
1069                 $didbegin = 0;
1070                 if (! $this->mTrxLevel) {
1071                         $this->begin();
1072                         $didbegin = 1;
1073                 }
1074                 if ( $ignore ) {
1075                         $olde = error_reporting( 0 );
1076                         // For future use, we may want to track the number of actual inserts
1077                         // Right now, insert (all writes) simply return true/false
1078                         $numrowsinserted = 0;
1079                 }
1080
1081                 $sql = "INSERT INTO $table (" . implode( ',', $keys ) . ') VALUES ';
1082                 switch($key_count) {
1083                         //case 0 impossible
1084                         case 1:
1085                                 $sql .= '(?)';
1086                                 break;
1087                         default:
1088                                 $sql .= '(?' . str_repeat(',?', $key_count-1) . ')';
1089                 }
1090                 $stmt = $this->prepare($sql);
1091
1092                 if ( !$ignore ) {
1093                         $first = true;
1094                         foreach ( $args as $row ) {
1095                                 // insert each row into the database
1096                                 $this->execute($stmt, $row);
1097                         }
1098                 }
1099                 else {
1100                         // we must have autocommit turned off -- transaction mode on
1101                         $this->begin();
1102
1103                         $res = true;
1104                         foreach ( $args as $row ) {
1105                                 if ( $ignore ) {
1106                                         $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
1107                                         db2_exec($this->mConn, $overhead, $this->mStmtOptions);
1108                                 }
1109
1110                                 $this->execute($sql, $row);
1111                                 if ( $ignore ) {
1112                                         $bar = $this->lastError();
1113                                         if (!$bar) {
1114                                                 db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore", $this->mStmtOptions );
1115                                         }
1116                                         else {
1117                                                 db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore", $this->mStmtOptions );
1118                                                 $numrowsinserted++;
1119                                         }
1120                                 }
1121                         }
1122                 }
1123
1124                 // commit either way
1125                 $this->commit();
1126
1127                 if ( $ignore ) {
1128                         $olde = error_reporting( $olde );
1129                         // Set the affected row count for the whole operation
1130                         $this->mAffectedRows = $numrowsinserted;
1131
1132                         // IGNORE always returns true
1133                         return true;
1134                 }
1135
1136                 return $res;
1137         }
1138
1139         /**
1140          * Given a table name and a hash of columns with values
1141          * Removes primary key columns from the hash where the value is NULL
1142          *
1143          * @param string $table Name of the table
1144          * @param array $args Array of hashes of column names with values
1145          * @return array Filtered array of hashes
1146          */
1147         private function removeNullPrimaryKeys($table, $args) {
1148                 $schema = $this->mSchema;
1149                 // find out the primary keys
1150                 $keyres = db2_primary_keys($this->mConn, null, strtoupper($schema), strtoupper($table));
1151                 $keys = array();
1152                 for ($row = $this->fetchObject($keyres); $row != null; $row = $this->fetchRow($keyres)) {
1153                         $keys[] = strtolower($row->column_name);
1154                 }
1155                 // remove primary keys
1156                 foreach ($args as $ai => $row) {
1157                         foreach ($keys as $ki => $key) {
1158                                 if ($row[$key] == NULL) {
1159                                         unset($row[$key]);
1160                                 }
1161                         }
1162                         $args[$ai] = $row;
1163                 }
1164                 // return modified hash
1165                 return $args;
1166         }
1167
1168         /**
1169          * UPDATE wrapper, takes a condition array and a SET array
1170          *
1171          * @param string $table  The table to UPDATE
1172          * @param array  $values An array of values to SET
1173          * @param array  $conds  An array of conditions (WHERE). Use '*' to update all rows.
1174          * @param string $fname  The Class::Function calling this function
1175          *                       (for the log)
1176          * @param array  $options An array of UPDATE options, can be one or
1177          *                        more of IGNORE, LOW_PRIORITY
1178          * @return bool
1179          */
1180         public function update( $table, $values, $conds, $fname = 'Database::update', $options = array() ) {
1181                 $table = $this->tableName( $table );
1182                 $opts = $this->makeUpdateOptions( $options );
1183                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET );
1184                 if ( $conds != '*' ) {
1185                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1186                 }
1187                 return $this->query( $sql, $fname );
1188         }
1189
1190         /**
1191          * DELETE query wrapper
1192          *
1193          * Use $conds == "*" to delete all rows
1194          */
1195         public function delete( $table, $conds, $fname = 'Database::delete' ) {
1196                 if ( !$conds ) {
1197                         throw new DBUnexpectedError( $this, 'Database::delete() called with no conditions' );
1198                 }
1199                 $table = $this->tableName( $table );
1200                 $sql = "DELETE FROM $table";
1201                 if ( $conds != '*' ) {
1202                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1203                 }
1204                 return $this->query( $sql, $fname );
1205         }
1206
1207         /**
1208          * Returns the number of rows affected by the last query or 0
1209          * @return int the number of rows affected by the last query
1210          */
1211         public function affectedRows() {
1212                 if ( !is_null( $this->mAffectedRows ) ) {
1213                         // Forced result for simulated queries
1214                         return $this->mAffectedRows;
1215                 }
1216                 if( empty( $this->mLastResult ) )
1217                         return 0;
1218                 return db2_num_rows( $this->mLastResult );
1219         }
1220
1221         /**
1222          * Simulates REPLACE with a DELETE followed by INSERT
1223          * @param $table Object
1224          * @param array $uniqueIndexes array consisting of indexes and arrays of indexes
1225          * @param array $rows Rows to insert
1226          * @param string $fname Name of the function for profiling
1227          * @return nothing
1228          */
1229         function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseIbm_db2::replace' ) {
1230                 $table = $this->tableName( $table );
1231
1232                 if (count($rows)==0) {
1233                         return;
1234                 }
1235
1236                 # Single row case
1237                 if ( !is_array( reset( $rows ) ) ) {
1238                         $rows = array( $rows );
1239                 }
1240
1241                 foreach( $rows as $row ) {
1242                         # Delete rows which collide
1243                         if ( $uniqueIndexes ) {
1244                                 $sql = "DELETE FROM $table WHERE ";
1245                                 $first = true;
1246                                 foreach ( $uniqueIndexes as $index ) {
1247                                         if ( $first ) {
1248                                                 $first = false;
1249                                                 $sql .= "(";
1250                                         } else {
1251                                                 $sql .= ') OR (';
1252                                         }
1253                                         if ( is_array( $index ) ) {
1254                                                 $first2 = true;
1255                                                 foreach ( $index as $col ) {
1256                                                         if ( $first2 ) {
1257                                                                 $first2 = false;
1258                                                         } else {
1259                                                                 $sql .= ' AND ';
1260                                                         }
1261                                                         $sql .= $col.'=' . $this->addQuotes( $row[$col] );
1262                                                 }
1263                                         } else {
1264                                                 $sql .= $index.'=' . $this->addQuotes( $row[$index] );
1265                                         }
1266                                 }
1267                                 $sql .= ')';
1268                                 $this->query( $sql, $fname );
1269                         }
1270
1271                         # Now insert the row
1272                         $sql = "INSERT INTO $table (" . $this->makeList( array_keys( $row ), LIST_NAMES ) .') VALUES (' .
1273                                 $this->makeList( $row, LIST_COMMA ) . ')';
1274                         $this->query( $sql, $fname );
1275                 }
1276         }
1277
1278         /**
1279          * Returns the number of rows in the result set
1280          * Has to be called right after the corresponding select query
1281          * @param object $res result set
1282          * @return int number of rows
1283          */
1284         public function numRows( $res ) {
1285                 if ( $res instanceof ResultWrapper ) {
1286                         $res = $res->result;
1287                 }
1288                 if ( $this->mNumRows ) {
1289                         return $this->mNumRows;
1290                 }
1291                 else {
1292                         return 0;
1293                 }
1294         }
1295
1296         /**
1297          * Moves the row pointer of the result set
1298          * @param object $res result set
1299          * @param int $row row number
1300          * @return success or failure
1301          */
1302         public function dataSeek( $res, $row ) {
1303                 if ( $res instanceof ResultWrapper ) {
1304                         $res = $res->result;
1305                 }
1306                 return db2_fetch_row( $res, $row );
1307         }
1308
1309         ###
1310         # Fix notices in Block.php
1311         ###
1312
1313         /**
1314          * Frees memory associated with a statement resource
1315          * @param object $res Statement resource to free
1316          * @return bool success or failure
1317          */
1318         public function freeResult( $res ) {
1319                 if ( $res instanceof ResultWrapper ) {
1320                         $res = $res->result;
1321                 }
1322                 if ( !@db2_free_result( $res ) ) {
1323                         throw new DBUnexpectedError($this,  "Unable to free DB2 result\n" );
1324                 }
1325         }
1326
1327         /**
1328          * Returns the number of columns in a resource
1329          * @param object $res Statement resource
1330          * @return Number of fields/columns in resource
1331          */
1332         public function numFields( $res ) {
1333                 if ( $res instanceof ResultWrapper ) {
1334                         $res = $res->result;
1335                 }
1336                 return db2_num_fields( $res );
1337         }
1338
1339         /**
1340          * Returns the nth column name
1341          * @param object $res Statement resource
1342          * @param int $n Index of field or column
1343          * @return string name of nth column
1344          */
1345         public function fieldName( $res, $n ) {
1346                 if ( $res instanceof ResultWrapper ) {
1347                         $res = $res->result;
1348                 }
1349                 return db2_field_name( $res, $n );
1350         }
1351
1352         /**
1353          * SELECT wrapper
1354          *
1355          * @param mixed  $table   Array or string, table name(s) (prefix auto-added)
1356          * @param mixed  $vars    Array or string, field name(s) to be retrieved
1357          * @param mixed  $conds   Array or string, condition(s) for WHERE
1358          * @param string $fname   Calling function name (use __METHOD__) for logs/profiling
1359          * @param array  $options Associative array of options (e.g. array('GROUP BY' => 'page_title')),
1360          *                        see Database::makeSelectOptions code for list of supported stuff
1361          * @param array $join_conds Associative array of table join conditions (optional)
1362          *                        (e.g. array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
1363          * @return mixed Database result resource (feed to Database::fetchObject or whatever), or false on failure
1364          */
1365         public function select( $table, $vars, $conds='', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1366         {
1367                 $res = parent::select( $table, $vars, $conds, $fname, $options, $join_conds );
1368
1369                 // We must adjust for offset
1370                 if ( isset( $options['LIMIT'] ) ) {
1371                         if ( isset ($options['OFFSET'] ) ) {
1372                                 $limit = $options['LIMIT'];
1373                                 $offset = $options['OFFSET'];
1374                         }
1375                 }
1376
1377
1378                 // DB2 does not have a proper num_rows() function yet, so we must emulate it
1379                 // DB2 9.5.3/9.5.4 and the corresponding ibm_db2 driver will introduce a working one
1380                 // Yay!
1381
1382                 // we want the count
1383                 $vars2 = array('count(*) as num_rows');
1384                 // respecting just the limit option
1385                 $options2 = array();
1386                 if ( isset( $options['LIMIT'] ) ) $options2['LIMIT'] = $options['LIMIT'];
1387                 // but don't try to emulate for GROUP BY
1388                 if ( isset( $options['GROUP BY'] ) ) return $res;
1389
1390                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2, $join_conds );
1391                 $obj = $this->fetchObject($res2);
1392                 $this->mNumRows = $obj->num_rows;
1393
1394                 $this->installPrint("DatabaseIbm_db2::select: There are $this->mNumRows rows.\n");
1395
1396                 return $res;
1397         }
1398
1399         /**
1400          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1401          * Has limited support for per-column options (colnum => 'DISTINCT')
1402          *
1403          * @private
1404          *
1405          * @param array $options an associative array of options to be turned into
1406          *              an SQL query, valid keys are listed in the function.
1407          * @return array
1408          */
1409         function makeSelectOptions( $options ) {
1410                 $preLimitTail = $postLimitTail = '';
1411                 $startOpts = '';
1412
1413                 $noKeyOptions = array();
1414                 foreach ( $options as $key => $option ) {
1415                         if ( is_numeric( $key ) ) {
1416                                 $noKeyOptions[$option] = true;
1417                         }
1418                 }
1419
1420                 if ( isset( $options['GROUP BY'] ) ) $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1421                 if ( isset( $options['HAVING'] ) ) $preLimitTail .= " HAVING {$options['HAVING']}";
1422                 if ( isset( $options['ORDER BY'] ) ) $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1423
1424                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) $startOpts .= 'DISTINCT';
1425
1426                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1427         }
1428
1429         /**
1430          * Returns link to IBM DB2 free download
1431          * @return string wikitext of a link to the server software's web site
1432          */
1433         public function getSoftwareLink() {
1434                 return "[http://www.ibm.com/software/data/db2/express/?s_cmp=ECDDWW01&s_tact=MediaWiki IBM DB2]";
1435         }
1436
1437         /**
1438          * @return String: Database type for use in messages
1439         */
1440         function getDBtypeForMsg() {
1441                 return 'IBM DB2';
1442         }
1443
1444         ###
1445         # Fix search crash
1446         ###
1447         /**
1448          * Get search engine class. All subclasses of this
1449          * need to implement this if they wish to use searching.
1450          *
1451          * @return string
1452          */
1453         public function getSearchEngine() {
1454                 return "SearchIBM_DB2";
1455         }
1456
1457         ###
1458         # Tuesday the 14th of October, 2008
1459         ###
1460         /**
1461          * Did the last database access fail because of deadlock?
1462          * @return bool
1463          */
1464         public function wasDeadlock() {
1465                 // get SQLSTATE
1466                 $err = $this->lastErrno();
1467                 switch($err) {
1468                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1469                         case '57011':   // sql0904n, Resource unavailable, no rollback
1470                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1471                         $this->installPrint("In a deadlock because of SQLSTATE $err");
1472                         return true;
1473                 }
1474                 return false;
1475         }
1476
1477         /**
1478          * Ping the server and try to reconnect if it there is no connection
1479          * The connection may be closed and reopened while this happens
1480          * @return bool whether the connection exists
1481          */
1482         public function ping() {
1483                 // db2_ping() doesn't exist
1484                 // Emulate
1485                 $this->close();
1486                 if ($this->mCataloged == NULL) {
1487                         return false;
1488                 }
1489                 else if ($this->mCataloged) {
1490                         $this->mConn = $this->openCataloged($this->mDBName, $this->mUser, $this->mPassword);
1491                 }
1492                 else if (!$this->mCataloged) {
1493                         $this->mConn = $this->openUncataloged($this->mDBName, $this->mUser, $this->mPassword, $this->mServer, $this->mPort);
1494                 }
1495                 return false;
1496         }
1497         ######################################
1498         # Unimplemented and not applicable
1499         ######################################
1500         /**
1501          * Not implemented
1502          * @return string ''
1503          * @deprecated
1504          */
1505         public function getStatus( $which="%" ) { $this->installPrint('Not implemented for DB2: getStatus()'); return ''; }
1506         /**
1507          * Not implemented
1508          * TODO
1509          * @return bool true
1510          */
1511         /**
1512          * Not implemented
1513          * @deprecated
1514          */
1515         public function setFakeSlaveLag( $lag ) { $this->installPrint('Not implemented for DB2: setFakeSlaveLag()'); }
1516         /**
1517          * Not implemented
1518          * @deprecated
1519          */
1520         public function setFakeMaster( $enabled = true ) { $this->installPrint('Not implemented for DB2: setFakeMaster()'); }
1521         /**
1522          * Not implemented
1523          * @return string $sql
1524          * @deprecated
1525          */
1526         public function limitResultForUpdate($sql, $num) { $this->installPrint('Not implemented for DB2: limitResultForUpdate()'); return $sql; }
1527
1528         /**
1529          * Only useful with fake prepare like in base Database class
1530          * @return      string
1531          */
1532         public function fillPreparedArg( $matches ) { $this->installPrint('Not useful for DB2: fillPreparedArg()'); return ''; }
1533
1534         ######################################
1535         # Reflection
1536         ######################################
1537
1538         /**
1539          * Query whether a given column exists in the mediawiki schema
1540          * @param string $table name of the table
1541          * @param string $field name of the column
1542          * @param string $fname function name for logging and profiling
1543          */
1544         public function fieldExists( $table, $field, $fname = 'DatabaseIbm_db2::fieldExists' ) {
1545                 $table = $this->tableName( $table );
1546                 $schema = $this->mSchema;
1547                 $etable = preg_replace("/'/", "''", $table);
1548                 $eschema = preg_replace("/'/", "''", $schema);
1549                 $ecol = preg_replace("/'/", "''", $field);
1550                 $sql = <<<SQL
1551 SELECT 1 as fieldexists
1552 FROM sysibm.syscolumns sc
1553 WHERE sc.name='$ecol' AND sc.tbname='$etable' AND sc.tbcreator='$eschema'
1554 SQL;
1555                 $res = $this->query( $sql, $fname );
1556                 $count = $res ? $this->numRows($res) : 0;
1557                 if ($res)
1558                         $this->freeResult( $res );
1559                 return $count;
1560         }
1561
1562         /**
1563          * Returns information about an index
1564          * If errors are explicitly ignored, returns NULL on failure
1565          * @param string $table table name
1566          * @param string $index index name
1567          * @param string
1568          * @return object query row in object form
1569          */
1570         public function indexInfo( $table, $index, $fname = 'DatabaseIbm_db2::indexExists' ) {
1571                 $table = $this->tableName( $table );
1572                 $sql = <<<SQL
1573 SELECT name as indexname
1574 FROM sysibm.sysindexes si
1575 WHERE si.name='$index' AND si.tbname='$table' AND sc.tbcreator='$this->mSchema'
1576 SQL;
1577                 $res = $this->query( $sql, $fname );
1578                 if ( !$res ) {
1579                         return NULL;
1580                 }
1581                 $row = $this->fetchObject( $res );
1582                 if ($row != NULL) return $row;
1583                 else return false;
1584         }
1585
1586         /**
1587          * Returns an information object on a table column
1588          * @param string $table table name
1589          * @param string $field column name
1590          * @return IBM_DB2Field
1591          */
1592         public function fieldInfo( $table, $field ) {
1593                 return IBM_DB2Field::fromText($this, $table, $field);
1594         }
1595
1596         /**
1597          * db2_field_type() wrapper
1598          * @param object $res Result of executed statement
1599          * @param mixed $index number or name of the column
1600          * @return string column type
1601          */
1602         public function fieldType( $res, $index ) {
1603                 if ( $res instanceof ResultWrapper ) {
1604                         $res = $res->result;
1605                 }
1606                 return db2_field_type( $res, $index );
1607         }
1608
1609         /**
1610          * Verifies that an index was created as unique
1611          * @param string $table table name
1612          * @param string $index index name
1613          * @param string $fnam function name for profiling
1614          * @return bool
1615          */
1616         public function indexUnique ($table, $index, $fname = 'Database::indexUnique' ) {
1617                 $table = $this->tableName( $table );
1618                 $sql = <<<SQL
1619 SELECT si.name as indexname
1620 FROM sysibm.sysindexes si
1621 WHERE si.name='$index' AND si.tbname='$table' AND sc.tbcreator='$this->mSchema'
1622 AND si.uniquerule IN ('U', 'P')
1623 SQL;
1624                 $res = $this->query( $sql, $fname );
1625                 if ( !$res ) {
1626                         return null;
1627                 }
1628                 if ($this->fetchObject( $res )) {
1629                         return true;
1630                 }
1631                 return false;
1632
1633         }
1634
1635         /**
1636          * Returns the size of a text field, or -1 for "unlimited"
1637          * @param string $table table name
1638          * @param string $field column name
1639          * @return int length or -1 for unlimited
1640          */
1641         public function textFieldSize( $table, $field ) {
1642                 $table = $this->tableName( $table );
1643                 $sql = <<<SQL
1644 SELECT length as size
1645 FROM sysibm.syscolumns sc
1646 WHERE sc.name='$field' AND sc.tbname='$table' AND sc.tbcreator='$this->mSchema'
1647 SQL;
1648                 $res = $this->query($sql);
1649                 $row = $this->fetchObject($res);
1650                 $size = $row->size;
1651                 $this->freeResult( $res );
1652                 return $size;
1653         }
1654
1655         /**
1656          * DELETE where the condition is a join
1657          * @param string $delTable deleting from this table
1658          * @param string $joinTable using data from this table
1659          * @param string $delVar variable in deleteable table
1660          * @param string $joinVar variable in data table
1661          * @param array $conds conditionals for join table
1662          * @param string $fname function name for profiling
1663          */
1664         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = "DatabaseIbm_db2::deleteJoin" ) {
1665                 if ( !$conds ) {
1666                         throw new DBUnexpectedError($this,  'Database::deleteJoin() called with empty $conds' );
1667                 }
1668
1669                 $delTable = $this->tableName( $delTable );
1670                 $joinTable = $this->tableName( $joinTable );
1671                 $sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
1672                 if ( $conds != '*' ) {
1673                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1674                 }
1675                 $sql .= ')';
1676
1677                 $this->query( $sql, $fname );
1678         }
1679
1680         /**
1681          * Estimate rows in dataset
1682          * Returns estimated count, based on COUNT(*) output
1683          * Takes same arguments as Database::select()
1684          * @param string $table table name
1685          * @param array $vars unused
1686          * @param array $conds filters on the table
1687          * @param string $fname function name for profiling
1688          * @param array $options options for select
1689          * @return int row count
1690          */
1691         public function estimateRowCount( $table, $vars='*', $conds='', $fname = 'Database::estimateRowCount', $options = array() ) {
1692                 $rows = 0;
1693                 $res = $this->select ($table, 'COUNT(*) as mwrowcount', $conds, $fname, $options );
1694                 if ($res) {
1695                         $row = $this->fetchRow($res);
1696                         $rows = (isset($row['mwrowcount'])) ? $row['mwrowcount'] : 0;
1697                 }
1698                 $this->freeResult($res);
1699                 return $rows;
1700         }
1701
1702         /**
1703          * Description is left as an exercise for the reader
1704          * @param mixed $b data to be encoded
1705          * @return IBM_DB2Blob
1706          */
1707         public function encodeBlob($b) {
1708                 return new IBM_DB2Blob($b);
1709         }
1710
1711         /**
1712          * Description is left as an exercise for the reader
1713          * @param IBM_DB2Blob $b data to be decoded
1714          * @return mixed
1715          */
1716         public function decodeBlob($b) {
1717                 return $b->getData();
1718         }
1719
1720         /**
1721          * Convert into a list of string being concatenated
1722          * @param array $stringList strings that need to be joined together by the SQL engine
1723          * @return string joined by the concatenation operator
1724          */
1725         public function buildConcat( $stringList ) {
1726                 // || is equivalent to CONCAT
1727                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1728                 return implode( ' || ', $stringList );
1729         }
1730
1731         /**
1732          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1733          * @param string $column name of timestamp column
1734          * @return string SQL code
1735          */
1736         public function extractUnixEpoch( $column ) {
1737                 // TODO
1738                 // see SpecialAncientpages
1739         }
1740
1741         ######################################
1742         # Prepared statements
1743         ######################################
1744
1745         /**
1746          * Intended to be compatible with the PEAR::DB wrapper functions.
1747          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1748          *
1749          * ? = scalar value, quoted as necessary
1750          * ! = raw SQL bit (a function for instance)
1751          * & = filename; reads the file and inserts as a blob
1752          *     (we don't use this though...)
1753          * @param string $sql SQL statement with appropriate markers
1754          * @return resource a prepared DB2 SQL statement
1755          */
1756         public function prepare( $sql, $func = 'DB2::prepare' ) {
1757                 $stmt = db2_prepare($this->mConn, $sql, $this->mStmtOptions);
1758                 return $stmt;
1759         }
1760
1761         /**
1762          * Frees resources associated with a prepared statement
1763          * @return bool success or failure
1764          */
1765         public function freePrepared( $prepared ) {
1766                 return db2_free_stmt($prepared);
1767         }
1768
1769         /**
1770          * Execute a prepared query with the various arguments
1771          * @param       string          $prepared       the prepared sql
1772          * @param       mixed           $args           Either an array here, or put scalars as varargs
1773          * @return      resource                                Results object
1774          */
1775         public function execute( $prepared, $args = null ) {
1776                 if( !is_array( $args ) ) {
1777                         # Pull the var args
1778                         $args = func_get_args();
1779                         array_shift( $args );
1780                 }
1781                 $res = db2_execute($prepared, $args);
1782                 return $res;
1783         }
1784
1785         /**
1786          * Prepare & execute an SQL statement, quoting and inserting arguments
1787          * in the appropriate places.
1788          * @param $query String
1789          * @param $args ...
1790          */
1791         public function safeQuery( $query, $args = null ) {
1792                 // copied verbatim from Database.php
1793                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1794                 if( !is_array( $args ) ) {
1795                         # Pull the var args
1796                         $args = func_get_args();
1797                         array_shift( $args );
1798                 }
1799                 $retval = $this->execute( $prepared, $args );
1800                 $this->freePrepared( $prepared );
1801                 return $retval;
1802         }
1803
1804         /**
1805          * For faking prepared SQL statements on DBs that don't support
1806          * it directly.
1807          * @param       resource        $preparedQuery  String: a 'preparable' SQL statement
1808          * @param       array           $args                   Array of arguments to fill it with
1809          * @return      string                                          executable statement
1810          */
1811         public function fillPrepared( $preparedQuery, $args ) {
1812                 reset( $args );
1813                 $this->preparedArgs =& $args;
1814
1815                 foreach ($args as $i => $arg) {
1816                         db2_bind_param($preparedQuery, $i+1, $args[$i]);
1817                 }
1818
1819                 return $preparedQuery;
1820         }
1821
1822         /**
1823          * Switches module between regular and install modes
1824          */
1825         public function setMode($mode) {
1826                 $old =  $this->mMode;
1827                 $this->mMode = $mode;
1828                 return $old;
1829         }
1830
1831         /**
1832          * Bitwise negation of a column or value in SQL
1833          * Same as (~field) in C
1834          * @param       string  $field
1835          * @return      string
1836          */
1837         function bitNot($field) {
1838                 //expecting bit-fields smaller than 4bytes
1839                 return 'BITNOT('.$bitField.')';
1840         }
1841
1842         /**
1843          * Bitwise AND of two columns or values in SQL
1844          * Same as (fieldLeft & fieldRight) in C
1845          * @param       string  $fieldLeft
1846          * @param       string  $fieldRight
1847          * @return      string
1848          */
1849         function bitAnd($fieldLeft, $fieldRight) {
1850                 return 'BITAND('.$fieldLeft.', '.$fieldRight.')';
1851         }
1852
1853         /**
1854          * Bitwise OR of two columns or values in SQL
1855          * Same as (fieldLeft | fieldRight) in C
1856          * @param       string  $fieldLeft
1857          * @param       string  $fieldRight
1858          * @return      string
1859          */
1860         function bitOr($fieldLeft, $fieldRight) {
1861                 return 'BITOR('.$fieldLeft.', '.$fieldRight.')';
1862         }
1863 }