path: root/includes/db/DatabaseOracle.php

<?php
/**
 * This is the Oracle database abstraction layer.
 *
 * @file
 * @ingroup Database
 */

/**
 * The oci8 extension is fairly weak and doesn't support oci_num_rows, among
 * other things.  We use a wrapper class to handle that and other
 * Oracle-specific bits, like converting column names back to lowercase.
 * @ingroup Database
 */
class ORAResult {
	private $rows;
	private $cursor;
	private $nrows;
	
	private $columns = array();

	private function array_unique_md( $array_in ) {
		$array_out = array();
		$array_hashes = array();

		foreach ( $array_in as $item ) {
			$hash = md5( serialize( $item ) );
			if ( !isset( $array_hashes[$hash] ) ) {
				$array_hashes[$hash] = $hash;
				$array_out[] = $item;
			}
		}

		return $array_out;
	}

	function __construct( &$db, $stmt, $unique = false ) {
		$this->db =& $db;

		if ( ( $this->nrows = oci_fetch_all( $stmt, $this->rows, 0, - 1, OCI_FETCHSTATEMENT_BY_ROW | OCI_NUM ) ) === false ) {
			$e = oci_error( $stmt );
			$db->reportQueryError( $e['message'], $e['code'], '', __METHOD__ );
			$this->free();
			return;
		}

		if ( $unique ) {
			$this->rows = $this->array_unique_md( $this->rows );
			$this->nrows = count( $this->rows );
		}

		if ($this->nrows > 0) {
			foreach ( $this->rows[0] as $k => $v ) {
				$this->columns[$k] = strtolower( oci_field_name( $stmt, $k + 1 ) );
			}
		}

		$this->cursor = 0;
		oci_free_statement( $stmt );
	}

	public function free() {
		unset($this->db);
	}

	public function seek( $row ) {
		$this->cursor = min( $row, $this->nrows );
	}

	public function numRows() {
		return $this->nrows;
	}

	public function numFields() {
		return count($this->columns);
	}

	public function fetchObject() {
		if ( $this->cursor >= $this->nrows ) {
			return false;
		}
		$row = $this->rows[$this->cursor++];
		$ret = new stdClass();
		foreach ( $row as $k => $v ) {
			$lc = $this->columns[$k];
			$ret->$lc = $v;
		}

		return $ret;
	}

	public function fetchRow() {
		if ( $this->cursor >= $this->nrows ) {
			return false;
		}

		$row = $this->rows[$this->cursor++];
		$ret = array();
		foreach ( $row as $k => $v ) {
			$lc = $this->columns[$k];
			$ret[$lc] = $v;
			$ret[$k] = $v;
		}
		return $ret;
	}
}

/**
 * Utility class.
 * @ingroup Database
 */
class ORAField implements Field {
	private $name, $tablename, $default, $max_length, $nullable,
		$is_pk, $is_unique, $is_multiple, $is_key, $type;

	function __construct( $info ) {
		$this->name = $info['column_name'];
		$this->tablename = $info['table_name'];
		$this->default = $info['data_default'];
		$this->max_length = $info['data_length'];
		$this->nullable = $info['not_null'];
		$this->is_pk = isset( $info['prim'] ) && $info['prim'] == 1 ? 1 : 0;
		$this->is_unique = isset( $info['uniq'] ) && $info['uniq'] == 1 ? 1 : 0;
		$this->is_multiple = isset( $info['nonuniq'] ) && $info['nonuniq'] == 1 ? 1 : 0;
		$this->is_key = ( $this->is_pk || $this->is_unique || $this->is_multiple );
		$this->type = $info['data_type'];
	}

	function name() {
		return $this->name;
	}

	function tableName() {
		return $this->tablename;
	}

	function defaultValue() {
		return $this->default;
	}

	function maxLength() {
		return $this->max_length;
	}

	function isNullable() {
		return $this->nullable;
	}

	function isKey() {
		return $this->is_key;
	}

	function isMultipleKey() {
		return $this->is_multiple;
	}

	function type() {
		return $this->type;
	}
}

/**
 * @ingroup Database
 */
class DatabaseOracle extends DatabaseBase {
	var $mInsertId = null;
	var $mLastResult = null;
	var $numeric_version = null;
	var $lastResult = null;
	var $cursor = 0;
	var $mAffectedRows;

	var $ignore_DUP_VAL_ON_INDEX = false;
	var $sequenceData = null;

	var $defaultCharset = 'AL32UTF8';

	var $mFieldInfoCache = array();

	function __construct( $server = false, $user = false, $password = false, $dbName = false,
		$flags = 0, $tablePrefix = 'get from global' )
	{
		$tablePrefix = $tablePrefix == 'get from global' ? $tablePrefix : strtoupper( $tablePrefix );
		parent::__construct( $server, $user, $password, $dbName, $flags, $tablePrefix );
		wfRunHooks( 'DatabaseOraclePostInit', array( $this ) );
	}

	function __destruct() {
		if ($this->mOpened) {
			wfSuppressWarnings();
			$this->close();
			wfRestoreWarnings();
		}
	}

	function getType() {
		return 'oracle';
	}

	function cascadingDeletes() {
		return true;
	}
	function cleanupTriggers() {
		return true;
	}
	function strictIPs() {
		return true;
	}
	function realTimestamps() {
		return true;
	}
	function implicitGroupby() {
		return false;
	}
	function implicitOrderby() {
		return false;
	}
	function searchableIPs() {
		return true;
	}

	static function newFromParams( $server, $user, $password, $dbName, $flags = 0 )
	{
		return new DatabaseOracle( $server, $user, $password, $dbName, $flags );
	}

	/**
	 * Usually aborts on failure
	 */
	function open( $server, $user, $password, $dbName ) {
		if ( !function_exists( 'oci_connect' ) ) {
			throw new DBConnectionError( $this, "Oracle functions missing, have you compiled PHP with the --with-oci8 option?\n (Note: if you recently installed PHP, you may need to restart your webserver and database)\n" );
		}

		$this->mUser = $user;
		$this->mPassword = $password;
		// changed internal variables functions
		// mServer now holds the TNS endpoint
		// mDBname is schema name if different from username
		if ( !$server ) {
			// backward compatibillity (server used to be null and TNS was supplied in dbname)
			$this->mServer = $dbName;
			$this->mDBname = $user;
		} else {
			$this->mServer = $server;
			if ( !$dbName ) {
				$this->mDBname = $user;
			} else {	
				$this->mDBname = $dbName;
			}
		}

		if ( !strlen( $user ) ) { # e.g. the class is being loaded
			return;
		}

		$session_mode = $this->mFlags & DBO_SYSDBA ? OCI_SYSDBA : OCI_DEFAULT;
		if ( $this->mFlags & DBO_DEFAULT ) {
			$this->mConn = oci_new_connect( $this->mUser, $this->mPassword, $this->mServer, $this->defaultCharset, $session_mode );
		} else {
			$this->mConn = oci_connect( $this->mUser, $this->mPassword, $this->mServer, $this->defaultCharset, $session_mode );
		}

		if ( $this->mUser != $this->mDBname ) {
			//change current schema in session
			$this->selectDB( $this->mDBname );
		}

		if ( !$this->mConn ) {
			throw new DBConnectionError( $this, $this->lastError() );
		}

		$this->mOpened = true;

		# removed putenv calls because they interfere with the system globaly
		$this->doQuery( 'ALTER SESSION SET NLS_TIMESTAMP_FORMAT=\'DD-MM-YYYY HH24:MI:SS.FF6\'' );
		$this->doQuery( 'ALTER SESSION SET NLS_TIMESTAMP_TZ_FORMAT=\'DD-MM-YYYY HH24:MI:SS.FF6\'' );
		return $this->mConn;
	}

	/**
	 * Closes a database connection, if it is open
	 * Returns success, true if already closed
	 */
	function close() {
		$this->mOpened = false;
		if ( $this->mConn ) {
			if ( $this->mTrxLevel ) {
				$this->commit();
			}
			return oci_close( $this->mConn );
		} else {
			return true;
		}
	}

	function execFlags() {
		return $this->mTrxLevel ? OCI_DEFAULT : OCI_COMMIT_ON_SUCCESS;
	}

	function doQuery( $sql ) {
		wfDebug( "SQL: [$sql]\n" );
		if ( !mb_check_encoding( $sql ) ) {
			throw new MWException( "SQL encoding is invalid\n$sql" );
		}

		// handle some oracle specifics
		// remove AS column/table/subquery namings
		if( !$this->getFlag( DBO_DDLMODE ) ) {
			$sql = preg_replace( '/ as /i', ' ', $sql );
		}

		// Oracle has issues with UNION clause if the statement includes LOB fields
		// So we do a UNION ALL and then filter the results array with array_unique
		$union_unique = ( preg_match( '/\/\* UNION_UNIQUE \*\/ /', $sql ) != 0 );
		// EXPLAIN syntax in Oracle is EXPLAIN PLAN FOR and it return nothing
		// you have to select data from plan table after explain
		$explain_id = date( 'dmYHis' );

		$sql = preg_replace( '/^EXPLAIN /', 'EXPLAIN PLAN SET STATEMENT_ID = \'' . $explain_id . '\' FOR', $sql, 1, $explain_count );

		wfSuppressWarnings();

		if ( ( $this->mLastResult = $stmt = oci_parse( $this->mConn, $sql ) ) === false ) {
			$e = oci_error( $this->mConn );
			$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
			return false;
		}

		if ( !oci_execute( $stmt, $this->execFlags() ) ) {
			$e = oci_error( $stmt );
			if ( !$this->ignore_DUP_VAL_ON_INDEX || $e['code'] != '1' ) {
				$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
				return false;
			}
		}

		wfRestoreWarnings();

		if ( $explain_count > 0 ) {
			return $this->doQuery( 'SELECT id, cardinality "ROWS" FROM plan_table WHERE statement_id = \'' . $explain_id . '\'' );
		} elseif ( oci_statement_type( $stmt ) == 'SELECT' ) {
			return new ORAResult( $this, $stmt, $union_unique );
		} else {
			$this->mAffectedRows = oci_num_rows( $stmt );
			return true;
		}
	}

	function queryIgnore( $sql, $fname = '' ) {
		return $this->query( $sql, $fname, true );
	}

	function freeResult( $res ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}
		
		$res->free();
	}

	function fetchObject( $res ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}
		
		return $res->fetchObject();
	}

	function fetchRow( $res ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}

		return $res->fetchRow();
	}

	function numRows( $res ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}

		return $res->numRows();
	}

	function numFields( $res ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}

		return $res->numFields();
	}

	function fieldName( $stmt, $n ) {
		return oci_field_name( $stmt, $n );
	}

	/**
	 * This must be called after nextSequenceVal
	 */
	function insertId() {
		return $this->mInsertId;
	}

	function dataSeek( $res, $row ) {
		if ( $res instanceof ORAResult ) {
			$res->seek( $row );
		} else {
			$res->result->seek( $row );
		}
	}

	function lastError() {
		if ( $this->mConn === false ) {
			$e = oci_error();
		} else {
			$e = oci_error( $this->mConn );
		}
		return $e['message'];
	}

	function lastErrno() {
		if ( $this->mConn === false ) {
			$e = oci_error();
		} else {
			$e = oci_error( $this->mConn );
		}
		return $e['code'];
	}

	function affectedRows() {
		return $this->mAffectedRows;
	}

	/**
	 * Returns information about an index
	 * If errors are explicitly ignored, returns NULL on failure
	 */
	function indexInfo( $table, $index, $fname = 'DatabaseOracle::indexExists' ) {
		return false;
	}

	function indexUnique( $table, $index, $fname = 'DatabaseOracle::indexUnique' ) {
		return false;
	}

	function insert( $table, $a, $fname = 'DatabaseOracle::insert', $options = array() ) {
		if ( !count( $a ) ) {
			return true;
		}

		if ( !is_array( $options ) ) {
			$options = array( $options );
		}

		if ( in_array( 'IGNORE', $options ) ) {
			$this->ignore_DUP_VAL_ON_INDEX = true;
		}

		if ( !is_array( reset( $a ) ) ) {
			$a = array( $a );
		}

		foreach ( $a as &$row ) {
			$this->insertOneRow( $table, $row, $fname );
		}
		$retVal = true;

		if ( in_array( 'IGNORE', $options ) ) {
			$this->ignore_DUP_VAL_ON_INDEX = false;
		}

		return $retVal;
	}

	private function fieldBindStatement ( $table, $col, &$val, $includeCol = false ) {
		$col_info = $this->fieldInfoMulti( $table, $col );
		$col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
		
		$bind = '';
		if ( is_numeric( $col ) ) {
			$bind = $val;
			$val = null;
			return $bind; 
		} else if ( $includeCol ) {
			$bind = "$col = ";
		}
		
		if ( $val == '' && $val !== 0 && $col_type != 'BLOB' && $col_type != 'CLOB' ) {
			$val = null;
		}

		if ( $val === null ) {
			if ( $col_info != false && $col_info->isNullable() == 0 && $col_info->defaultValue() != null ) {
				$bind .= 'DEFAULT';
			} else {
				$bind .= 'NULL';
			}
		} else {
			$bind .= ':' . $col;
		}
		
		return $bind;
	}

	private function insertOneRow( $table, $row, $fname ) {
		global $wgContLang;

		$table = $this->tableName( $table );
		// "INSERT INTO tables (a, b, c)"
		$sql = "INSERT INTO " . $table . " (" . join( ',', array_keys( $row ) ) . ')';
		$sql .= " VALUES (";

		// for each value, append ":key"
		$first = true;
		foreach ( $row as $col => &$val ) {
			if ( !$first ) {
				$sql .= ', ';
			} else {
				$first = false;
			}
			
			$sql .= $this->fieldBindStatement( $table, $col, $val );
		}
		$sql .= ')';

		if ( ( $this->mLastResult = $stmt = oci_parse( $this->mConn, $sql ) ) === false ) {
			$e = oci_error( $this->mConn );
			$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
			return false;
		}
		foreach ( $row as $col => &$val ) {
			$col_info = $this->fieldInfoMulti( $table, $col );
			$col_type = $col_info != false ? $col_info->type() : 'CONSTANT';

			if ( $val === null ) {
				// do nothing ... null was inserted in statement creation
			} elseif ( $col_type != 'BLOB' && $col_type != 'CLOB' ) {
				if ( is_object( $val ) ) {
					$val = $val->fetch();
				}

				if ( preg_match( '/^timestamp.*/i', $col_type ) == 1 && strtolower( $val ) == 'infinity' ) {
					$val = '31-12-2030 12:00:00.000000';
				}

				$val = ( $wgContLang != null ) ? $wgContLang->checkTitleEncoding( $val ) : $val;
				if ( oci_bind_by_name( $stmt, ":$col", $val ) === false ) {
					$e = oci_error( $stmt );
					$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
					return false;
				}
			} else {
				if ( ( $lob[$col] = oci_new_descriptor( $this->mConn, OCI_D_LOB ) ) === false ) {
					$e = oci_error( $stmt );
					throw new DBUnexpectedError( $this, "Cannot create LOB descriptor: " . $e['message'] );
				}

				if ( is_object( $val ) ) {
					$val = $val->fetch();
				}

				if ( $col_type == 'BLOB' ) {
					$lob[$col]->writeTemporary( $val, OCI_TEMP_BLOB );
					oci_bind_by_name( $stmt, ":$col", $lob[$col], - 1, OCI_B_BLOB );
				} else {
					$lob[$col]->writeTemporary( $val, OCI_TEMP_CLOB );
					oci_bind_by_name( $stmt, ":$col", $lob[$col], - 1, OCI_B_CLOB );
				}
			}
		}

		wfSuppressWarnings();

		if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
			$e = oci_error( $stmt );
			if ( !$this->ignore_DUP_VAL_ON_INDEX || $e['code'] != '1' ) {
				$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
				return false;
			} else {
				$this->mAffectedRows = oci_num_rows( $stmt );
			}
		} else {
			$this->mAffectedRows = oci_num_rows( $stmt );
		}

		wfRestoreWarnings();

		if ( isset( $lob ) ) {
			foreach ( $lob as $lob_v ) {
				$lob_v->free();
			}
		}

		if ( !$this->mTrxLevel ) {
			oci_commit( $this->mConn );
		}

		oci_free_statement( $stmt );
	}

	function insertSelect( $destTable, $srcTable, $varMap, $conds, $fname = 'DatabaseOracle::insertSelect',
		$insertOptions = array(), $selectOptions = array() )
	{
		$destTable = $this->tableName( $destTable );
		if ( !is_array( $selectOptions ) ) {
			$selectOptions = array( $selectOptions );
		}
		list( $startOpts, $useIndex, $tailOpts ) = $this->makeSelectOptions( $selectOptions );
		if ( is_array( $srcTable ) ) {
			$srcTable =  implode( ',', array_map( array( &$this, 'tableName' ), $srcTable ) );
		} else {
			$srcTable = $this->tableName( $srcTable );
		}

		if ( ( $sequenceData = $this->getSequenceData( $destTable ) ) !== false &&
				!isset( $varMap[$sequenceData['column']] ) )
		{
			$varMap[$sequenceData['column']] = 'GET_SEQUENCE_VALUE(\'' . $sequenceData['sequence'] . '\')';
		}

		// count-alias subselect fields to avoid abigious definition errors
		$i = 0;
		foreach ( $varMap as &$val ) {
			$val = $val . ' field' . ( $i++ );
		}

		$sql = "INSERT INTO $destTable (" . implode( ',', array_keys( $varMap ) ) . ')' .
			" SELECT $startOpts " . implode( ',', $varMap ) .
			" FROM $srcTable $useIndex ";
		if ( $conds != '*' ) {
			$sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
		}
		$sql .= " $tailOpts";

		if ( in_array( 'IGNORE', $insertOptions ) ) {
			$this->ignore_DUP_VAL_ON_INDEX = true;
		}

		$retval = $this->query( $sql, $fname );

		if ( in_array( 'IGNORE', $insertOptions ) ) {
			$this->ignore_DUP_VAL_ON_INDEX = false;
		}

		return $retval;
	}

	function tableName( $name ) {
		global $wgSharedDB, $wgSharedPrefix, $wgSharedTables;
		/*
		Replace reserved words with better ones
		Using uppercase because that's the only way Oracle can handle
		quoted tablenames
		*/
		switch( $name ) {
			case 'user':
				$name = 'MWUSER';
				break;
			case 'text':
				$name = 'PAGECONTENT';
				break;
		}

		/*
			The rest of procedure is equal to generic Databse class
			except for the quoting style
		*/
		if ( $name[0] == '"' && substr( $name, - 1, 1 ) == '"' ) {
			return $name;
		}
		if ( preg_match( '/(^|\s)(DISTINCT|JOIN|ON|AS)(\s|$)/i', $name ) !== 0 ) {
			return $name;
		}
		$dbDetails = array_reverse( explode( '.', $name, 2 ) );
		if ( isset( $dbDetails[1] ) ) {
			@list( $table, $database ) = $dbDetails;
		} else {
			@list( $table ) = $dbDetails;
		}

		$prefix = $this->mTablePrefix;

		if ( isset( $database ) ) {
			$table = ( $table[0] == '`' ? $table : "`{$table}`" );
		}

		if ( !isset( $database ) && isset( $wgSharedDB ) && $table[0] != '"'
			&& isset( $wgSharedTables )
			&& is_array( $wgSharedTables )
			&& in_array( $table, $wgSharedTables )
		) {
			$database = $wgSharedDB;
			$prefix   = isset( $wgSharedPrefix ) ? $wgSharedPrefix : $prefix;
		}

		if ( isset( $database ) ) {
			$database = ( $database[0] == '"' ? $database : "\"{$database}\"" );
		}
		$table = ( $table[0] == '"') ? $table : "\"{$prefix}{$table}\"" ;

		$tableName = ( isset( $database ) ? "{$database}.{$table}" : "{$table}" );

		return strtoupper( $tableName );
	}

	function tableNameInternal( $name ) {
		$name = $this->tableName( $name );
		return preg_replace( '/.*\."(.*)"/', '$1', $name);
	}

	/**
	 * Return the next in a sequence, save the value for retrieval via insertId()
	 */
	function nextSequenceValue( $seqName ) {
		$res = $this->query( "SELECT $seqName.nextval FROM dual" );
		$row = $this->fetchRow( $res );
		$this->mInsertId = $row[0];
		return $this->mInsertId;
	}

	/**
	 * Return sequence_name if table has a sequence
	 */
	private function getSequenceData( $table ) {
		if ( $this->sequenceData == null ) {
			$result = $this->doQuery( 'SELECT lower(us.sequence_name), lower(utc.table_name), lower(utc.column_name) from user_sequences us, user_tab_columns utc where us.sequence_name = utc.table_name||\'_\'||utc.column_name||\'_SEQ\'' );

			while ( ( $row = $result->fetchRow() ) !== false ) {
				$this->sequenceData[$this->tableName( $row[1] )] = array(
					'sequence' => $row[0],
					'column' => $row[2]
				);
			}
		}

		return ( isset( $this->sequenceData[$table] ) ) ? $this->sequenceData[$table] : false;
	}

	/**
	 * REPLACE query wrapper
	 * Oracle simulates this with a DELETE followed by INSERT
	 * $row is the row to insert, an associative array
	 * $uniqueIndexes is an array of indexes. Each element may be either a
	 * field name or an array of field names
	 *
	 * It may be more efficient to leave off unique indexes which are unlikely to collide.
	 * However if you do this, you run the risk of encountering errors which wouldn't have
	 * occurred in MySQL.
	 *
	 * @param $table String: table name
	 * @param $uniqueIndexes Array: array of indexes. Each element may be
	 *                       either a field name or an array of field names
	 * @param $rows Array: rows to insert to $table
	 * @param $fname String: function name, you can use __METHOD__ here
	 */
	function replace( $table, $uniqueIndexes, $rows, $fname = 'DatabaseOracle::replace' ) {
		$table = $this->tableName( $table );

		if ( count( $rows ) == 0 ) {
			return;
		}

		# Single row case
		if ( !is_array( reset( $rows ) ) ) {
			$rows = array( $rows );
		}

		$sequenceData = $this->getSequenceData( $table );

		foreach ( $rows as $row ) {
			# Delete rows which collide
			if ( $uniqueIndexes ) {
				$condsDelete = array();
				foreach ( $uniqueIndexes as $index ) {
					$condsDelete[$index] = $row[$index];
				}
				if ( count( $condsDelete ) > 0 ) {
					$this->delete( $table, $condsDelete, $fname );
				}
			}

			if ( $sequenceData !== false && !isset( $row[$sequenceData['column']] ) ) {
				$row[$sequenceData['column']] = $this->nextSequenceValue( $sequenceData['sequence'] );
			}

			# Now insert the row
			$this->insert( $table, $row, $fname );
		}
	}

	# DELETE where the condition is a join
	function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname = 'DatabaseOracle::deleteJoin' ) {
		if ( !$conds ) {
			throw new DBUnexpectedError( $this, 'DatabaseOracle::deleteJoin() called with empty $conds' );
		}

		$delTable = $this->tableName( $delTable );
		$joinTable = $this->tableName( $joinTable );
		$sql = "DELETE FROM $delTable WHERE $delVar IN (SELECT $joinVar FROM $joinTable ";
		if ( $conds != '*' ) {
			$sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
		}
		$sql .= ')';

		$this->query( $sql, $fname );
	}

	# Returns the size of a text field, or -1 for "unlimited"
	function textFieldSize( $table, $field ) {
		$fieldInfoData = $this->fieldInfo( $table, $field );
		return $fieldInfoData->maxLength();
	}

	function limitResult( $sql, $limit, $offset = false ) {
		if ( $offset === false ) {
			$offset = 0;
		}
		return "SELECT * FROM ($sql) WHERE rownum >= (1 + $offset) AND rownum < (1 + $limit + $offset)";
	}

	function encodeBlob( $b ) {
		return new Blob( $b );
	}

	function decodeBlob( $b ) {
		if ( $b instanceof Blob ) {
			$b = $b->fetch();
		}
		return $b;
	}

	function unionQueries( $sqls, $all ) {
		$glue = ' UNION ALL ';
		return 'SELECT * ' . ( $all ? '':'/* UNION_UNIQUE */ ' ) . 'FROM (' . implode( $glue, $sqls ) . ')' ;
	}

	public function unixTimestamp( $field ) {
		return "((trunc($field) - to_date('19700101','YYYYMMDD')) * 86400)";
	}

	function wasDeadlock() {
		return $this->lastErrno() == 'OCI-00060';
	}

	function duplicateTableStructure( $oldName, $newName, $temporary = false, $fname = 'DatabaseOracle::duplicateTableStructure' ) {
		global $wgDBprefix;
		
		$temporary = $temporary ? 'TRUE' : 'FALSE';

		$newName = trim( strtoupper( $newName ), '"');
		$oldName = trim( strtoupper( $oldName ), '"');

		$tabName = substr( $newName, strlen( $wgDBprefix ) );
		$oldPrefix = substr( $oldName, 0, strlen( $oldName ) - strlen( $tabName ) );

		return $this->doQuery( 'BEGIN DUPLICATE_TABLE(\'' . $tabName . '\', \'' . $oldPrefix . '\', \'' . strtoupper( $wgDBprefix ) . '\', ' . $temporary . '); END;' );
	}

	function listTables( $prefix = null, $fname = 'DatabaseOracle::listTables' ) {
		$listWhere = '';
		if (!empty($prefix)) {
			$listWhere = ' AND table_name LIKE \''.strtoupper($prefix).'%\'';
		}
		
		$result = $this->doQuery( "SELECT table_name FROM user_tables WHERE table_name NOT LIKE '%!_IDX$_' ESCAPE '!' $listWhere" );

		// dirty code ... i know
		$endArray = array();
		$endArray[] = $prefix.'MWUSER';
		$endArray[] = $prefix.'PAGE';
		$endArray[] = $prefix.'IMAGE';
		$fixedOrderTabs = $endArray;
		while (($row = $result->fetchRow()) !== false) {
			if (!in_array($row['table_name'], $fixedOrderTabs))
				$endArray[] = $row['table_name'];
		}

		return $endArray;
	}

	public function dropTable( $tableName, $fName = 'DatabaseOracle::dropTable' ) {
		$tableName = $this->tableName($tableName);
		if( !$this->tableExists( $tableName ) ) {
			return false;
		}
		
		return $this->doQuery( "DROP TABLE $tableName CASCADE CONSTRAINTS PURGE" );
	}

	function timestamp( $ts = 0 ) {
		return wfTimestamp( TS_ORACLE, $ts );
	}

	/**
	 * Return aggregated value function call
	 */
	function aggregateValue ( $valuedata, $valuename = 'value' ) {
		return $valuedata;
	}

	function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
		# Ignore errors during error handling to avoid infinite
		# recursion
		$ignore = $this->ignoreErrors( true );
		++$this->mErrorCount;

		if ( $ignore || $tempIgnore ) {
			wfDebug( "SQL ERROR (ignored): $error\n" );
			$this->ignoreErrors( $ignore );
		} else {
			throw new DBQueryError( $this, $error, $errno, $sql, $fname );
		}
	}

	/**
	 * @return string wikitext of a link to the server software's web site
	 */
	public static function getSoftwareLink() {
		return '[http://www.oracle.com/ Oracle]';
	}

	/**
	 * @return string Version information from the database
	 */
	function getServerVersion() {
		//better version number, fallback on driver
		$rset = $this->doQuery( 'SELECT version FROM product_component_version WHERE UPPER(product) LIKE \'ORACLE DATABASE%\'' );
		if ( !( $row =  $rset->fetchRow() ) ) {
			return oci_server_version( $this->mConn );
		} 
		return $row['version'];
	}

	/**
	 * Query whether a given table exists (in the given schema, or the default mw one if not given)
	 */
	function tableExists( $table ) {
		$table = $this->addQuotes( trim( $this->tableName($table), '"' ) );
		$owner = $this->addQuotes( strtoupper( $this->mDBname ) );
		$SQL = "SELECT 1 FROM all_tables WHERE owner=$owner AND table_name=$table";
		$res = $this->doQuery( $SQL );
		if ( $res ) {
			$count = $res->numRows();
			$res->free();
		} else {
			$count = 0;
		}
		return $count!=0;
	}

	/**
	 * Function translates mysql_fetch_field() functionality on ORACLE.
	 * Caching is present for reducing query time.
	 * For internal calls. Use fieldInfo for normal usage.
	 * Returns false if the field doesn't exist
	 *
	 * @param $table Array
	 * @param $field String
	 */
	private function fieldInfoMulti( $table, $field ) {
		$field = strtoupper( $field );
		if ( is_array( $table ) ) {
			$table = array_map( array( &$this, 'tableNameInternal' ), $table );
			$tableWhere = 'IN (';
			foreach( $table as &$singleTable ) {
				$singleTable = strtoupper( trim( $singleTable, '"' ) );
				if ( isset( $this->mFieldInfoCache["$singleTable.$field"] ) ) {
					return $this->mFieldInfoCache["$singleTable.$field"];
				}
				$tableWhere .= '\'' . $singleTable . '\',';
			}
			$tableWhere = rtrim( $tableWhere, ',' ) . ')';
		} else {
			$table = strtoupper( trim( $this->tableNameInternal( $table ), '"' ) );
			if ( isset( $this->mFieldInfoCache["$table.$field"] ) ) {
				return $this->mFieldInfoCache["$table.$field"];
			}
			$tableWhere = '= \''.$table.'\'';
		}

		$fieldInfoStmt = oci_parse( $this->mConn, 'SELECT * FROM wiki_field_info_full WHERE table_name '.$tableWhere.' and column_name = \''.$field.'\'' );
		if ( oci_execute( $fieldInfoStmt, $this->execFlags() ) === false ) {
			$e = oci_error( $fieldInfoStmt );
			$this->reportQueryError( $e['message'], $e['code'], 'fieldInfo QUERY', __METHOD__ );
			return false;
		}
		$res = new ORAResult( $this, $fieldInfoStmt );
		if ( $res->numRows() == 0 ) {
			if ( is_array( $table ) ) {
				foreach( $table as &$singleTable ) {
					$this->mFieldInfoCache["$singleTable.$field"] = false;
				}
			} else {
				$this->mFieldInfoCache["$table.$field"] = false;
			}
			$fieldInfoTemp = null;
		} else {
			$fieldInfoTemp = new ORAField( $res->fetchRow() );
			$table = $fieldInfoTemp->tableName();
			$this->mFieldInfoCache["$table.$field"] = $fieldInfoTemp;
		}
		$res->free();
		return $fieldInfoTemp;
	}

	function fieldInfo( $table, $field ) {
		if ( is_array( $table ) ) {
			throw new DBUnexpectedError( $this, 'DatabaseOracle::fieldInfo called with table array!' );
		}
		return $this->fieldInfoMulti ($table, $field);
	}

	function begin( $fname = 'DatabaseOracle::begin' ) {
		$this->mTrxLevel = 1;
	}

	function commit( $fname = 'DatabaseOracle::commit' ) {
		if ( $this->mTrxLevel ) {
			oci_commit( $this->mConn );
			$this->mTrxLevel = 0;
		}
	}

	function rollback( $fname = 'DatabaseOracle::rollback' ) {
		if ( $this->mTrxLevel ) {
			oci_rollback( $this->mConn );
			$this->mTrxLevel = 0;
		}
	}

	/* Not even sure why this is used in the main codebase... */
	function limitResultForUpdate( $sql, $num ) {
		return $sql;
	}

	/* defines must comply with ^define\s*([^\s=]*)\s*=\s?'\{\$([^\}]*)\}'; */
	function sourceStream( $fp, $lineCallback = false, $resultCallback = false, $fname = 'DatabaseOracle::sourceStream' ) {
		$cmd = '';
		$done = false;
		$dollarquote = false;

		$replacements = array();

		while ( ! feof( $fp ) ) {
			if ( $lineCallback ) {
				call_user_func( $lineCallback );
			}
			$line = trim( fgets( $fp, 1024 ) );
			$sl = strlen( $line ) - 1;

			if ( $sl < 0 ) {
				continue;
			}
			if ( '-' == $line { 0 } && '-' == $line { 1 } ) {
				continue;
			}

			// Allow dollar quoting for function declarations
			if ( substr( $line, 0, 8 ) == '/*$mw$*/' ) {
				if ( $dollarquote ) {
					$dollarquote = false;
					$line = str_replace( '/*$mw$*/', '', $line ); // remove dollarquotes
					$done = true;
				} else {
					$dollarquote = true;
				}
			} elseif ( !$dollarquote ) {
				if ( ';' == $line { $sl } && ( $sl < 2 || ';' != $line { $sl - 1 } ) ) {
					$done = true;
					$line = substr( $line, 0, $sl );
				}
			}

			if ( $cmd != '' ) {
				$cmd .= ' ';
			}
			$cmd .= "$line\n";

			if ( $done ) {
				$cmd = str_replace( ';;', ";", $cmd );
				if ( strtolower( substr( $cmd, 0, 6 ) ) == 'define' ) {
					if ( preg_match( '/^define\s*([^\s=]*)\s*=\s*\'\{\$([^\}]*)\}\'/', $cmd, $defines ) ) {
						$replacements[$defines[2]] = $defines[1];
					}
				} else {
					foreach ( $replacements as $mwVar => $scVar ) {
						$cmd = str_replace( '&' . $scVar . '.', '`{$' . $mwVar . '}`', $cmd );
					}

					$cmd = $this->replaceVars( $cmd );
					$res = $this->doQuery( $cmd );
					if ( $resultCallback ) {
						call_user_func( $resultCallback, $res, $this );
					}

					if ( false === $res ) {
						$err = $this->lastError();
						return "Query \"{$cmd}\" failed with error code \"$err\".\n";
					}
				}

				$cmd = '';
				$done = false;
			}
		}
		return true;
	}

	function selectDB( $db ) {
		$this->mDBname = $db;
		if ( $db == null || $db == $this->mUser ) {
			return true;
		}
		$sql = 'ALTER SESSION SET CURRENT_SCHEMA=' . strtoupper($db);
		$stmt = oci_parse( $this->mConn, $sql );
		wfSuppressWarnings();
		$success = oci_execute( $stmt );
		wfRestoreWarnings();
		if ( !$success ) {
			$e = oci_error( $stmt );
			if ( $e['code'] != '1435' ) {
				$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
			}
			return false;
		}
		return true;
	}

	function strencode( $s ) {
		return str_replace( "'", "''", $s );
	}

	function addQuotes( $s ) {
		global $wgContLang;
		if ( isset( $wgContLang->mLoaded ) && $wgContLang->mLoaded ) {
			$s = $wgContLang->checkTitleEncoding( $s );
		}
		return "'" . $this->strencode( $s ) . "'";
	}

	public function addIdentifierQuotes( $s ) {
		if ( !$this->mFlags & DBO_DDLMODE ) {
			$s = '"' . str_replace( '"', '""', $s ) . '"';
		}
		return $s;
	}

	function selectRow( $table, $vars, $conds, $fname = 'DatabaseOracle::selectRow', $options = array(), $join_conds = array() ) {
		global $wgContLang;

		if ($conds != null) {
			$conds2 = array();
			$conds = ( !is_array( $conds ) ) ? array( $conds ) : $conds;
			foreach ( $conds as $col => $val ) {
				$col_info = $this->fieldInfoMulti( $table, $col );
				$col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
				if ( $col_type == 'CLOB' ) {
					$conds2['TO_CHAR(' . $col . ')'] = $wgContLang->checkTitleEncoding( $val );
				} elseif ( $col_type == 'VARCHAR2' && !mb_check_encoding( $val ) ) {
					$conds2[$col] = $wgContLang->checkTitleEncoding( $val );
				} else {
					$conds2[$col] = $val;
				}
			}

			return parent::selectRow( $table, $vars, $conds2, $fname, $options, $join_conds );
		} else {
			return parent::selectRow( $table, $vars, $conds, $fname, $options, $join_conds );
		}
	}

	/**
	 * Returns an optional USE INDEX clause to go after the table, and a
	 * string to go at the end of the query
	 *
	 * @private
	 *
	 * @param $options Array: an associative array of options to be turned into
	 *              an SQL query, valid keys are listed in the function.
	 * @return array
	 */
	function makeSelectOptions( $options ) {
		$preLimitTail = $postLimitTail = '';
		$startOpts = '';

		$noKeyOptions = array();
		foreach ( $options as $key => $option ) {
			if ( is_numeric( $key ) ) {
				$noKeyOptions[$option] = true;
			}
		}

		if ( isset( $options['GROUP BY'] ) ) {
			$preLimitTail .= " GROUP BY {$options['GROUP BY']}";
		}
		if ( isset( $options['ORDER BY'] ) ) {
			$preLimitTail .= " ORDER BY {$options['ORDER BY']}";
		}

		# if ( isset( $noKeyOptions['FOR UPDATE'] ) ) $tailOpts .= ' FOR UPDATE';
		# if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) $tailOpts .= ' LOCK IN SHARE MODE';
		if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
			$startOpts .= 'DISTINCT';
		}

		if ( isset( $options['USE INDEX'] ) && ! is_array( $options['USE INDEX'] ) ) {
			$useIndex = $this->useIndexClause( $options['USE INDEX'] );
		} else {
			$useIndex = '';
		}

		return array( $startOpts, $useIndex, $preLimitTail, $postLimitTail );
	}

	public function delete( $table, $conds, $fname = 'DatabaseOracle::delete' ) {
		global $wgContLang;

		if ( $wgContLang != null && $conds != null && $conds != '*' ) {
			$conds2 = array();
			$conds = ( !is_array( $conds ) ) ? array( $conds ) : $conds;
			foreach ( $conds as $col => $val ) {
				$col_info = $this->fieldInfoMulti( $table, $col );
				$col_type = $col_info != false ? $col_info->type() : 'CONSTANT';
				if ( $col_type == 'CLOB' ) {
					$conds2['TO_CHAR(' . $col . ')'] = $wgContLang->checkTitleEncoding( $val );
				} else {
					if ( is_array( $val ) ) {
						$conds2[$col] = $val;
						foreach ( $conds2[$col] as &$val2 ) {
							$val2 = $wgContLang->checkTitleEncoding( $val2 );
						}
					} else {
						$conds2[$col] = $wgContLang->checkTitleEncoding( $val );
					}
				}
			}

			return parent::delete( $table, $conds2, $fname );
		} else {
			return parent::delete( $table, $conds, $fname );
		}
	}

	function update( $table, $values, $conds, $fname = 'DatabaseOracle::update', $options = array() ) {
		global $wgContLang;
		
		$table = $this->tableName( $table );
		$opts = $this->makeUpdateOptions( $options );
		$sql = "UPDATE $opts $table SET ";
		
		$first = true;
		foreach ( $values as $col => &$val ) {
			$sqlSet = $this->fieldBindStatement( $table, $col, $val, true );
			
			if ( !$first ) {
				$sqlSet = ', ' . $sqlSet;
			} else {
				$first = false;
			}
			$sql .= $sqlSet;
		}

		if ( $conds != '*' ) {
			$sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
		}

		if ( ( $this->mLastResult = $stmt = oci_parse( $this->mConn, $sql ) ) === false ) {
			$e = oci_error( $this->mConn );
			$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
			return false;
		}
		foreach ( $values as $col => &$val ) {
			$col_info = $this->fieldInfoMulti( $table, $col );
			$col_type = $col_info != false ? $col_info->type() : 'CONSTANT';

			if ( $val === null ) {
				// do nothing ... null was inserted in statement creation
			} elseif ( $col_type != 'BLOB' && $col_type != 'CLOB' ) {
				if ( is_object( $val ) ) {
					$val = $val->getData();
				}

				if ( preg_match( '/^timestamp.*/i', $col_type ) == 1 && strtolower( $val ) == 'infinity' ) {
					$val = '31-12-2030 12:00:00.000000';
				}

				$val = ( $wgContLang != null ) ? $wgContLang->checkTitleEncoding( $val ) : $val;
				if ( oci_bind_by_name( $stmt, ":$col", $val ) === false ) {
					$e = oci_error( $stmt );
					$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
					return false;
				}
			} else {
				if ( ( $lob[$col] = oci_new_descriptor( $this->mConn, OCI_D_LOB ) ) === false ) {
					$e = oci_error( $stmt );
					throw new DBUnexpectedError( $this, "Cannot create LOB descriptor: " . $e['message'] );
				}

				if ( $col_type == 'BLOB' ) { 
					$lob[$col]->writeTemporary( $val ); 
					oci_bind_by_name( $stmt, ":$col", $lob[$col], - 1, SQLT_BLOB );
				} else {
					$lob[$col]->writeTemporary( $val );
					oci_bind_by_name( $stmt, ":$col", $lob[$col], - 1, OCI_B_CLOB );
				}
			}
		}

		wfSuppressWarnings();

		if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
			$e = oci_error( $stmt );
			if ( !$this->ignore_DUP_VAL_ON_INDEX || $e['code'] != '1' ) {
				$this->reportQueryError( $e['message'], $e['code'], $sql, __METHOD__ );
				return false;
			} else {
				$this->mAffectedRows = oci_num_rows( $stmt );
			}
		} else {
			$this->mAffectedRows = oci_num_rows( $stmt );
		}

		wfRestoreWarnings();

		if ( isset( $lob ) ) {
			foreach ( $lob as $lob_v ) {
				$lob_v->free();
			}
		}

		if ( !$this->mTrxLevel ) {
			oci_commit( $this->mConn );
		}

		oci_free_statement( $stmt );
	}

	function bitNot( $field ) {
		// expecting bit-fields smaller than 4bytes
		return 'BITNOT(' . $field . ')';
	}

	function bitAnd( $fieldLeft, $fieldRight ) {
		return 'BITAND(' . $fieldLeft . ', ' . $fieldRight . ')';
	}

	function bitOr( $fieldLeft, $fieldRight ) {
		return 'BITOR(' . $fieldLeft . ', ' . $fieldRight . ')';
	}

	function setFakeMaster( $enabled = true ) { }

	function getDBname() {
		return $this->mDBname;
	}

	function getServer() {
		return $this->mServer;
	}

	public function getSearchEngine() {
		return 'SearchOracle';
	}
} // end DatabaseOracle class