/includes/db/Database.php

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<?php
/**
 * @defgroup Database Database
 *
 * @file
 * @ingroup Database
 * This file deals with database interface functions
 * and query specifics/optimisations
 */

/** Number of times to re-try an operation in case of deadlock */
define( 'DEADLOCK_TRIES', 4 );
/** Minimum time to wait before retry, in microseconds */
define( 'DEADLOCK_DELAY_MIN', 500000 );
/** Maximum time to wait before retry */
define( 'DEADLOCK_DELAY_MAX', 1500000 );

/**
 * Base interface for all DBMS-specific code. At a bare minimum, all of the
 * following must be implemented to support MediaWiki
 *
 * @file
 * @ingroup Database
 */
interface DatabaseType {
	/**
	 * Get the type of the DBMS, as it appears in $wgDBtype.
	 *
	 * @return string
	 */
	function getType();

	/**
	 * Open a connection to the database. Usually aborts on failure
	 *
	 * @param $server String: database server host
	 * @param $user String: database user name
	 * @param $password String: database user password
	 * @param $dbName String: database name
	 * @return bool
	 * @throws DBConnectionError
	 */
	function open( $server, $user, $password, $dbName );

	/**
	 * Fetch the next row from the given result object, in object form.
	 * Fields can be retrieved with $row->fieldname, with fields acting like
	 * member variables.
	 *
	 * @param $res ResultWrapper|object as returned from DatabaseBase::query(), etc.
	 * @return Row object
	 * @throws DBUnexpectedError Thrown if the database returns an error
	 */
	function fetchObject( $res );

	/**
	 * Fetch the next row from the given result object, in associative array
	 * form.  Fields are retrieved with $row['fieldname'].
	 *
	 * @param $res ResultWrapper result object as returned from DatabaseBase::query(), etc.
	 * @return Row object
	 * @throws DBUnexpectedError Thrown if the database returns an error
	 */
	function fetchRow( $res );

	/**
	 * Get the number of rows in a result object
	 *
	 * @param $res Mixed: A SQL result
	 * @return int
	 */
	function numRows( $res );

	/**
	 * Get the number of fields in a result object
	 * @see http://www.php.net/mysql_num_fields
	 *
	 * @param $res Mixed: A SQL result
	 * @return int
	 */
	function numFields( $res );

	/**
	 * Get a field name in a result object
	 * @see http://www.php.net/mysql_field_name
	 *
	 * @param $res Mixed: A SQL result
	 * @param $n Integer
	 * @return string
	 */
	function fieldName( $res, $n );

	/**
	 * Get the inserted value of an auto-increment row
	 *
	 * The value inserted should be fetched from nextSequenceValue()
	 *
	 * Example:
	 * $id = $dbw->nextSequenceValue('page_page_id_seq');
	 * $dbw->insert('page',array('page_id' => $id));
	 * $id = $dbw->insertId();
	 *
	 * @return int
	 */
	function insertId();

	/**
	 * Change the position of the cursor in a result object
	 * @see http://www.php.net/mysql_data_seek
	 *
	 * @param $res Mixed: A SQL result
	 * @param $row Mixed: Either MySQL row or ResultWrapper
	 */
	function dataSeek( $res, $row );

	/**
	 * Get the last error number
	 * @see http://www.php.net/mysql_errno
	 *
	 * @return int
	 */
	function lastErrno();

	/**
	 * Get a description of the last error
	 * @see http://www.php.net/mysql_error
	 *
	 * @return string
	 */
	function lastError();

	/**
	 * mysql_fetch_field() wrapper
	 * Returns false if the field doesn't exist
	 *
	 * @param $table string: table name
	 * @param $field string: field name
	 *
	 * @return Field
	 */
	function fieldInfo( $table, $field );

	/**
	 * Get information about an index into an object
	 * @param $table string: Table name
	 * @param $index string: Index name
	 * @param $fname string: Calling function name
	 * @return Mixed: Database-specific index description class or false if the index does not exist
	 */
	function indexInfo( $table, $index, $fname = 'Database::indexInfo' );

	/**
	 * Get the number of rows affected by the last write query
	 * @see http://www.php.net/mysql_affected_rows
	 *
	 * @return int
	 */
	function affectedRows();

	/**
	 * Wrapper for addslashes()
	 *
	 * @param $s string: to be slashed.
	 * @return string: slashed string.
	 */
	function strencode( $s );

	/**
	 * Returns a wikitext link to the DB's website, e.g.,
	 *     return "[http://www.mysql.com/ MySQL]";
	 * Should at least contain plain text, if for some reason
	 * your database has no website.
	 *
	 * @return string: wikitext of a link to the server software's web site
	 */
	static function getSoftwareLink();

	/**
	 * A string describing the current software version, like from
	 * mysql_get_server_info().
	 *
	 * @return string: Version information from the database server.
	 */
	function getServerVersion();

	/**
	 * A string describing the current software version, and possibly
	 * other details in a user-friendly way.  Will be listed on Special:Version, etc.
	 * Use getServerVersion() to get machine-friendly information.
	 *
	 * @return string: Version information from the database server
	 */
	function getServerInfo();
}

/**
 * Database abstraction object
 * @ingroup Database
 */
abstract class DatabaseBase implements DatabaseType {

# ------------------------------------------------------------------------------
# Variables
# ------------------------------------------------------------------------------

	protected $mLastQuery = '';
	protected $mDoneWrites = false;
	protected $mPHPError = false;

	protected $mServer, $mUser, $mPassword, $mDBname;

	/**
	 * @var DatabaseBase
	 */
	protected $mConn = null;
	protected $mOpened = false;

	protected $mTablePrefix;
	protected $mFlags;
	protected $mTrxLevel = 0;
	protected $mErrorCount = 0;
	protected $mLBInfo = array();
	protected $mFakeSlaveLag = null, $mFakeMaster = false;
	protected $mDefaultBigSelects = null;
	protected $mSchemaVars = false;

	protected $preparedArgs;

	protected $htmlErrors;

	protected $delimiter = ';';

# ------------------------------------------------------------------------------
# Accessors
# ------------------------------------------------------------------------------
	# These optionally set a variable and return the previous state

	/**
	 * A string describing the current software version, and possibly
	 * other details in a user-friendly way.  Will be listed on Special:Version, etc.
	 * Use getServerVersion() to get machine-friendly information.
	 *
	 * @return string: Version information from the database server
	 */
	public function getServerInfo() {
		return $this->getServerVersion();
	}

	/**
	 * Boolean, controls output of large amounts of debug information.
	 * @param $debug bool|null
	 *   - true to enable debugging
	 *   - false to disable debugging
	 *   - omitted or null to do nothing
	 *
	 * @return The previous value of the flag
	 */
	function debug( $debug = null ) {
		return wfSetBit( $this->mFlags, DBO_DEBUG, $debug );
	}

	/**
	 * Turns buffering of SQL result sets on (true) or off (false). Default is
	 * "on".
	 *
	 * Unbuffered queries are very troublesome in MySQL:
	 *
	 *   - If another query is executed while the first query is being read
	 *     out, the first query is killed. This means you can't call normal
	 *     MediaWiki functions while you are reading an unbuffered query result
	 *     from a normal wfGetDB() connection.
	 *
	 *   - Unbuffered queries cause the MySQL server to use large amounts of
	 *     memory and to hold broad locks which block other queries.
	 *
	 * If you want to limit client-side memory, it's almost always better to
	 * split up queries into batches using a LIMIT clause than to switch off
	 * buffering.
	 *
	 * @param $buffer null|bool
	 *
	 * @return The previous value of the flag
	 */
	function bufferResults( $buffer = null ) {
		if ( is_null( $buffer ) ) {
			return !(bool)( $this->mFlags & DBO_NOBUFFER );
		} else {
			return !wfSetBit( $this->mFlags, DBO_NOBUFFER, !$buffer );
		}
	}

	/**
	 * Turns on (false) or off (true) the automatic generation and sending
	 * of a "we're sorry, but there has been a database error" page on
	 * database errors. Default is on (false). When turned off, the
	 * code should use lastErrno() and lastError() to handle the
	 * situation as appropriate.
	 *
	 * @param $ignoreErrors bool|null
	 *
	 * @return bool The previous value of the flag.
	 */
	function ignoreErrors( $ignoreErrors = null ) {
		return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
	}

	/**
	 * Gets or sets the current transaction level.
	 *
	 * Historically, transactions were allowed to be "nested". This is no
	 * longer supported, so this function really only returns a boolean.
	 *
	 * @param $level An integer (0 or 1), or omitted to leave it unchanged.
	 * @return The previous value
	 */
	function trxLevel( $level = null ) {
		return wfSetVar( $this->mTrxLevel, $level );
	}

	/**
	 * Get/set the number of errors logged. Only useful when errors are ignored
	 * @param $count The count to set, or omitted to leave it unchanged.
	 * @return The error count
	 */
	function errorCount( $count = null ) {
		return wfSetVar( $this->mErrorCount, $count );
	}

	/**
	 * Get/set the table prefix.
	 * @param $prefix The table prefix to set, or omitted to leave it unchanged.
	 * @return The previous table prefix.
	 */
	function tablePrefix( $prefix = null ) {
		return wfSetVar( $this->mTablePrefix, $prefix );
	}

	/**
	 * Get properties passed down from the server info array of the load
	 * balancer.
	 *
	 * @param $name string The entry of the info array to get, or null to get the
	 *   whole array
	 *
	 * @return LoadBalancer|null
	 */
	function getLBInfo( $name = null ) {
		if ( is_null( $name ) ) {
			return $this->mLBInfo;
		} else {
			if ( array_key_exists( $name, $this->mLBInfo ) ) {
				return $this->mLBInfo[$name];
			} else {
				return null;
			}
		}
	}

	/**
	 * Set the LB info array, or a member of it. If called with one parameter,
	 * the LB info array is set to that parameter. If it is called with two
	 * parameters, the member with the given name is set to the given value.
	 *
	 * @param $name
	 * @param $value
	 */
	function setLBInfo( $name, $value = null ) {
		if ( is_null( $value ) ) {
			$this->mLBInfo = $name;
		} else {
			$this->mLBInfo[$name] = $value;
		}
	}

	/**
	 * Set lag time in seconds for a fake slave
	 *
	 * @param $lag int
	 */
	function setFakeSlaveLag( $lag ) {
		$this->mFakeSlaveLag = $lag;
	}

	/**
	 * Make this connection a fake master
	 *
	 * @param $enabled bool
	 */
	function setFakeMaster( $enabled = true ) {
		$this->mFakeMaster = $enabled;
	}

	/**
	 * Returns true if this database supports (and uses) cascading deletes
	 *
	 * @return bool
	 */
	function cascadingDeletes() {
		return false;
	}

	/**
	 * Returns true if this database supports (and uses) triggers (e.g. on the page table)
	 *
	 * @return bool
	 */
	function cleanupTriggers() {
		return false;
	}

	/**
	 * Returns true if this database is strict about what can be put into an IP field.
	 * Specifically, it uses a NULL value instead of an empty string.
	 *
	 * @return bool
	 */
	function strictIPs() {
		return false;
	}

	/**
	 * Returns true if this database uses timestamps rather than integers
	 *
	 * @return bool
	*/
	function realTimestamps() {
		return false;
	}

	/**
	 * Returns true if this database does an implicit sort when doing GROUP BY
	 *
	 * @return bool
	 */
	function implicitGroupby() {
		return true;
	}

	/**
	 * Returns true if this database does an implicit order by when the column has an index
	 * For example: SELECT page_title FROM page LIMIT 1
	 *
	 * @return bool
	 */
	function implicitOrderby() {
		return true;
	}

	/**
	 * Returns true if this database requires that SELECT DISTINCT queries require that all
	   ORDER BY expressions occur in the SELECT list per the SQL92 standard
	 *
	 * @return bool
	 */
	function standardSelectDistinct() {
		return true;
	}

	/**
	 * Returns true if this database can do a native search on IP columns
	 * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
	 *
	 * @return bool
	 */
	function searchableIPs() {
		return false;
	}

	/**
	 * Returns true if this database can use functional indexes
	 *
	 * @return bool
	 */
	function functionalIndexes() {
		return false;
	}

	/**
	 * Return the last query that went through DatabaseBase::query()
	 * @return String
	 */
	function lastQuery() {
		return $this->mLastQuery;
	}

	/**
	 * Returns true if the connection may have been used for write queries.
	 * Should return true if unsure.
	 *
	 * @return bool
	 */
	function doneWrites() {
		return $this->mDoneWrites;
	}

	/**
	 * Is a connection to the database open?
	 * @return Boolean
	 */
	function isOpen() {
		return $this->mOpened;
	}

	/**
	 * Set a flag for this connection
	 *
	 * @param $flag Integer: DBO_* constants from Defines.php:
	 *   - DBO_DEBUG: output some debug info (same as debug())
	 *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
	 *   - DBO_IGNORE: ignore errors (same as ignoreErrors())
	 *   - DBO_TRX: automatically start transactions
	 *   - DBO_DEFAULT: automatically sets DBO_TRX if not in command line mode
	 *       and removes it in command line mode
	 *   - DBO_PERSISTENT: use persistant database connection
	 */
	function setFlag( $flag ) {
		$this->mFlags |= $flag;
	}

	/**
	 * Clear a flag for this connection
	 *
	 * @param $flag: same as setFlag()'s $flag param
	 */
	function clearFlag( $flag ) {
		$this->mFlags &= ~$flag;
	}

	/**
	 * Returns a boolean whether the flag $flag is set for this connection
	 *
	 * @param $flag: same as setFlag()'s $flag param
	 * @return Boolean
	 */
	function getFlag( $flag ) {
		return !!( $this->mFlags & $flag );
	}

	/**
	 * General read-only accessor
	 *
	 * @param $name string
	 *
	 * @return string
	 */
	function getProperty( $name ) {
		return $this->$name;
	}

	/**
	 * @return string
	 */
	function getWikiID() {
		if ( $this->mTablePrefix ) {
			return "{$this->mDBname}-{$this->mTablePrefix}";
		} else {
			return $this->mDBname;
		}
	}

	/**
	 * Return a path to the DBMS-specific schema file, otherwise default to tables.sql
	 *
	 * @return string
	 */
	public function getSchemaPath() {
		global $IP;
		if ( file_exists( "$IP/maintenance/" . $this->getType() . "/tables.sql" ) ) {
			return "$IP/maintenance/" . $this->getType() . "/tables.sql";
		} else {
			return "$IP/maintenance/tables.sql";
		}
	}

# ------------------------------------------------------------------------------
# Other functions
# ------------------------------------------------------------------------------

	/**
	 * Constructor.
	 * @param $server String: database server host
	 * @param $user String: database user name
	 * @param $password String: database user password
	 * @param $dbName String: database name
	 * @param $flags
	 * @param $tablePrefix String: database table prefixes. By default use the prefix gave in LocalSettings.php
	 */
	function __construct( $server = false, $user = false, $password = false, $dbName = false,
		$flags = 0, $tablePrefix = 'get from global'
	) {
		global $wgDBprefix, $wgCommandLineMode;

		$this->mFlags = $flags;

		if ( $this->mFlags & DBO_DEFAULT ) {
			if ( $wgCommandLineMode ) {
				$this->mFlags &= ~DBO_TRX;
			} else {
				$this->mFlags |= DBO_TRX;
			}
		}

		/** Get the default table prefix*/
		if ( $tablePrefix == 'get from global' ) {
			$this->mTablePrefix = $wgDBprefix;
		} else {
			$this->mTablePrefix = $tablePrefix;
		}

		if ( $user ) {
			$this->open( $server, $user, $password, $dbName );
		}
	}

	/**
	 * Called by serialize. Throw an exception when DB connection is serialized.
	 * This causes problems on some database engines because the connection is
	 * not restored on unserialize.
	 */
	public function __sleep() {
		throw new MWException( 'Database serialization may cause problems, since the connection is not restored on wakeup.' );
	}

	/**
	 * Same as new DatabaseMysql( ... ), kept for backward compatibility
	 * @deprecated since 1.17
	 *
	 * @param $server
	 * @param $user
	 * @param $password
	 * @param $dbName
	 * @param $flags int
	 * @return DatabaseMysql
	 */
	static function newFromParams( $server, $user, $password, $dbName, $flags = 0 ) {
		wfDeprecated( __METHOD__, '1.17' );
		return new DatabaseMysql( $server, $user, $password, $dbName, $flags );
	}

	/**
	 * Same as new factory( ... ), kept for backward compatibility
	 * @deprecated since 1.18
	 * @see Database::factory()
	 */
	public final static function newFromType( $dbType, $p = array() ) {
		wfDeprecated( __METHOD__, '1.18' );
		if ( isset( $p['tableprefix'] ) ) {
			$p['tablePrefix'] = $p['tableprefix'];
		}
		return self::factory( $dbType, $p );
	}

	/**
	 * Given a DB type, construct the name of the appropriate child class of
	 * DatabaseBase. This is designed to replace all of the manual stuff like:
	 *	$class = 'Database' . ucfirst( strtolower( $type ) );
	 * as well as validate against the canonical list of DB types we have
	 *
	 * This factory function is mostly useful for when you need to connect to a
	 * database other than the MediaWiki default (such as for external auth,
	 * an extension, et cetera). Do not use this to connect to the MediaWiki
	 * database. Example uses in core:
	 * @see LoadBalancer::reallyOpenConnection()
	 * @see ExternalUser_MediaWiki::initFromCond()
	 * @see ForeignDBRepo::getMasterDB()
	 * @see WebInstaller_DBConnect::execute()
	 *
	 * @param $dbType String A possible DB type
	 * @param $p Array An array of options to pass to the constructor.
	 *    Valid options are: host, user, password, dbname, flags, tablePrefix
	 * @return DatabaseBase subclass or null
	 */
	public final static function factory( $dbType, $p = array() ) {
		$canonicalDBTypes = array(
			'mysql', 'postgres', 'sqlite', 'oracle', 'mssql', 'ibm_db2'
		);
		$dbType = strtolower( $dbType );
		$class = 'Database' . ucfirst( $dbType );

		if( in_array( $dbType, $canonicalDBTypes ) || ( class_exists( $class ) && is_subclass_of( $class, 'DatabaseBase' ) ) ) {
			return new $class(
				isset( $p['host'] ) ? $p['host'] : false,
				isset( $p['user'] ) ? $p['user'] : false,
				isset( $p['password'] ) ? $p['password'] : false,
				isset( $p['dbname'] ) ? $p['dbname'] : false,
				isset( $p['flags'] ) ? $p['flags'] : 0,
				isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global'
			);
		} else {
			return null;
		}
	}

	protected function installErrorHandler() {
		$this->mPHPError = false;
		$this->htmlErrors = ini_set( 'html_errors', '0' );
		set_error_handler( array( $this, 'connectionErrorHandler' ) );
	}

	/**
	 * @return bool|string
	 */
	protected function restoreErrorHandler() {
		restore_error_handler();
		if ( $this->htmlErrors !== false ) {
			ini_set( 'html_errors', $this->htmlErrors );
		}
		if ( $this->mPHPError ) {
			$error = preg_replace( '!\[<a.*</a>\]!', '', $this->mPHPError );
			$error = preg_replace( '!^.*?:(.*)$!', '$1', $error );
			return $error;
		} else {
			return false;
		}
	}

	/**
	 * @param $errno
	 * @param $errstr
	 */
	protected function connectionErrorHandler( $errno,  $errstr ) {
		$this->mPHPError = $errstr;
	}

	/**
	 * Closes a database connection.
	 * if it is open : commits any open transactions
	 *
	 * @return Bool operation success. true if already closed.
	 */
	function close() {
		# Stub, should probably be overridden
		return true;
	}

	/**
	 * @param $error String: fallback error message, used if none is given by DB
	 */
	function reportConnectionError( $error = 'Unknown error' ) {
		$myError = $this->lastError();
		if ( $myError ) {
			$error = $myError;
		}

		# New method
		throw new DBConnectionError( $this, $error );
	}

	/**
	 * The DBMS-dependent part of query()
	 *
	 * @param  $sql String: SQL query.
	 * @return ResultWrapper Result object to feed to fetchObject, fetchRow, ...; or false on failure
	 */
	protected abstract function doQuery( $sql );

	/**
	 * Determine whether a query writes to the DB.
	 * Should return true if unsure.
	 *
	 * @param $sql string
	 *
	 * @return bool
	 */
	function isWriteQuery( $sql ) {
		return !preg_match( '/^(?:SELECT|BEGIN|COMMIT|SET|SHOW|\(SELECT)\b/i', $sql );
	}

	/**
	 * Run an SQL query and return the result. Normally throws a DBQueryError
	 * on failure. If errors are ignored, returns false instead.
	 *
	 * In new code, the query wrappers select(), insert(), update(), delete(),
	 * etc. should be used where possible, since they give much better DBMS
	 * independence and automatically quote or validate user input in a variety
	 * of contexts. This function is generally only useful for queries which are
	 * explicitly DBMS-dependent and are unsupported by the query wrappers, such
	 * as CREATE TABLE.
	 *
	 * However, the query wrappers themselves should call this function.
	 *
	 * @param  $sql        String: SQL query
	 * @param  $fname      String: Name of the calling function, for profiling/SHOW PROCESSLIST
	 *     comment (you can use __METHOD__ or add some extra info)
	 * @param  $tempIgnore Boolean:   Whether to avoid throwing an exception on errors...
	 *     maybe best to catch the exception instead?
	 * @return boolean|ResultWrapper. true for a successful write query, ResultWrapper object
	 *     for a successful read query, or false on failure if $tempIgnore set
	 * @throws DBQueryError Thrown when the database returns an error of any kind
	 */
	public function query( $sql, $fname = '', $tempIgnore = false ) {
		$isMaster = !is_null( $this->getLBInfo( 'master' ) );
		if ( !Profiler::instance()->isStub() ) {
			# generalizeSQL will probably cut down the query to reasonable
			# logging size most of the time. The substr is really just a sanity check.

			if ( $isMaster ) {
				$queryProf = 'query-m: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
				$totalProf = 'DatabaseBase::query-master';
			} else {
				$queryProf = 'query: ' . substr( DatabaseBase::generalizeSQL( $sql ), 0, 255 );
				$totalProf = 'DatabaseBase::query';
			}

			wfProfileIn( $totalProf );
			wfProfileIn( $queryProf );
		}

		$this->mLastQuery = $sql;
		if ( !$this->mDoneWrites && $this->isWriteQuery( $sql ) ) {
			# Set a flag indicating that writes have been done
			wfDebug( __METHOD__ . ": Writes done: $sql\n" );
			$this->mDoneWrites = true;
		}

		# Add a comment for easy SHOW PROCESSLIST interpretation
		global $wgUser;
		if ( is_object( $wgUser ) && $wgUser->isItemLoaded( 'name' ) ) {
			$userName = $wgUser->getName();
			if ( mb_strlen( $userName ) > 15 ) {
				$userName = mb_substr( $userName, 0, 15 ) . '...';
			}
			$userName = str_replace( '/', '', $userName );
		} else {
			$userName = '';
		}
		$commentedSql = preg_replace( '/\s/', " /* $fname $userName */ ", $sql, 1 );

		# If DBO_TRX is set, start a transaction
		if ( ( $this->mFlags & DBO_TRX ) && !$this->trxLevel() &&
			$sql != 'BEGIN' && $sql != 'COMMIT' && $sql != 'ROLLBACK' ) {
			# avoid establishing transactions for SHOW and SET statements too -
			# that would delay transaction initializations to once connection
			# is really used by application
			$sqlstart = substr( $sql, 0, 10 ); // very much worth it, benchmark certified(tm)
			if ( strpos( $sqlstart, "SHOW " ) !== 0 && strpos( $sqlstart, "SET " ) !== 0 )
				$this->begin( __METHOD__ . " ($fname)" );
		}

		if ( $this->debug() ) {
			static $cnt = 0;

			$cnt++;
			$sqlx = substr( $commentedSql, 0, 500 );
			$sqlx = strtr( $sqlx, "\t\n", '  ' );

			$master = $isMaster ? 'master' : 'slave';
			wfDebug( "Query {$this->mDBname} ($cnt) ($master): $sqlx\n" );
		}

		if ( istainted( $sql ) & TC_MYSQL ) {
			throw new MWException( 'Tainted query found' );
		}

		$queryId = MWDebug::query( $sql, $fname, $isMaster );

		# Do the query and handle errors
		$ret = $this->doQuery( $commentedSql );

		MWDebug::queryTime( $queryId );

		# Try reconnecting if the connection was lost
		if ( false === $ret && $this->wasErrorReissuable() ) {
			# Transaction is gone, like it or not
			$this->mTrxLevel = 0;
			wfDebug( "Connection lost, reconnecting...\n" );

			if ( $this->ping() ) {
				wfDebug( "Reconnected\n" );
				$sqlx = substr( $commentedSql, 0, 500 );
				$sqlx = strtr( $sqlx, "\t\n", '  ' );
				global $wgRequestTime;
				$elapsed = round( microtime( true ) - $wgRequestTime, 3 );
				if ( $elapsed < 300 ) {
					# Not a database error to lose a transaction after a minute or two
					wfLogDBError( "Connection lost and reconnected after {$elapsed}s, query: $sqlx\n" );
				}
				$ret = $this->doQuery( $commentedSql );
			} else {
				wfDebug( "Failed\n" );
			}
		}

		if ( false === $ret ) {
			$this->reportQueryError( $this->lastError(), $this->lastErrno(), $sql, $fname, $tempIgnore );
		}

		if ( !Profiler::instance()->isStub() ) {
			wfProfileOut( $queryProf );
			wfProfileOut( $totalProf );
		}

		return $this->resultObject( $ret );
	}

	/**
	 * Report a query error. Log the error, and if neither the object ignore
	 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
	 *
	 * @param $error String
	 * @param $errno Integer
	 * @param $sql String
	 * @param $fname String
	 * @param $tempIgnore Boolean
	 */
	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 {
			$sql1line = str_replace( "\n", "\\n", $sql );
			wfLogDBError( "$fname\t{$this->mServer}\t$errno\t$error\t$sql1line\n" );
			wfDebug( "SQL ERROR: " . $error . "\n" );
			throw new DBQueryError( $this, $error, $errno, $sql, $fname );
		}
	}

	/**
	 * Intended to be compatible with the PEAR::DB wrapper functions.
	 * http://pear.php.net/manual/en/package.database.db.intro-execute.php
	 *
	 * ? = scalar value, quoted as necessary
	 * ! = raw SQL bit (a function for instance)
	 * & = filename; reads the file and inserts as a blob
	 *     (we don't use this though...)
	 *
	 * This function should not be used directly by new code outside of the
	 * database classes. The query wrapper functions (select() etc.) should be
	 * used instead.
	 *
	 * @param $sql string
	 * @param $func string
	 *
	 * @return array
	 */
	function prepare( $sql, $func = 'DatabaseBase::prepare' ) {
		/* MySQL doesn't support prepared statements (yet), so just
		   pack up the query for reference. We'll manually replace
		   the bits later. */
		return array( 'query' => $sql, 'func' => $func );
	}

	/**
	 * Free a prepared query, generated by prepare().
	 * @param $prepared
	 */
	function freePrepared( $prepared ) {
		/* No-op by default */
	}

	/**
	 * Execute a prepared query with the various arguments
	 * @param $prepared String: the prepared sql
	 * @param $args Mixed: Either an array here, or put scalars as varargs
	 *
	 * @return ResultWrapper
	 */
	function execute( $prepared, $args = null ) {
		if ( !is_array( $args ) ) {
			# Pull the var args
			$args = func_get_args();
			array_shift( $args );
		}

		$sql = $this->fillPrepared( $prepared['query'], $args );

		return $this->query( $sql, $prepared['func'] );
	}

	/**
	 * Prepare & execute an SQL statement, quoting and inserting arguments
	 * in the appropriate places.
	 *
	 * This function should not be used directly by new code outside of the
	 * database classes. The query wrapper functions (select() etc.) should be
	 * used instead.
	 *
	 * @param $query String
	 * @param $args ...
	 *
	 * @return ResultWrapper
	 */
	function safeQuery( $query, $args = null ) {
		$prepared = $this->prepare( $query, 'DatabaseBase::safeQuery' );

		if ( !is_array( $args ) ) {
			# Pull the var args
			$args = func_get_args();
			array_shift( $args );
		}

		$retval = $this->execute( $prepared, $args );
		$this->freePrepared( $prepared );

		return $retval;
	}

	/**
	 * For faking prepared SQL statements on DBs that don't support
	 * it directly.
	 * @param $preparedQuery String: a 'preparable' SQL statement
	 * @param $args Array of arguments to fill it with
	 * @return string executable SQL
	 */
	function fillPrepared( $preparedQuery, $args ) {
		reset( $args );
		$this->preparedArgs =& $args;

		return preg_replace_callback( '/(\\\\[?!&]|[?!&])/',
			array( &$this, 'fillPreparedArg' ), $preparedQuery );
	}

	/**
	 * preg_callback func for fillPrepared()
	 * The arguments should be in $this->preparedArgs and must not be touched
	 * while we're doing this.
	 *
	 * @param $matches Array
	 * @return String
	 */
	function fillPreparedArg( $matches ) {
		switch( $matches[1] ) {
			case '\\?': return '?';
			case '\\!': return '!';
			case '\\&': return '&';
		}

		list( /* $n */ , $arg ) = each( $this->preparedArgs );

		switch( $matches[1] ) {
			case '?': return $this->addQuotes( $arg );
			case '!': return $arg;
			case '&':
				# return $this->addQuotes( file_get_contents( $arg ) );
				throw new DBUnexpectedError( $this, '& mode is not implemented. If it\'s really needed, uncomment the line above.' );
			default:
				throw new DBUnexpectedError( $this, 'Received invalid match. This should never happen!' );
		}
	}

	/**
	 * Free a result object returned by query() or select(). It's usually not
	 * necessary to call this, just use unset() or let the variable holding
	 * the result object go out of scope.
	 *
	 * @param $res Mixed: A SQL result
	 */
	function freeResult( $res ) {
	}

	/**
	 * Simple UPDATE wrapper.
	 * Usually throws a DBQueryError on failure.
	 * If errors are explicitly ignored, returns success
	 *
	 * This function exists for historical reasons, DatabaseBase::update() has a more standard
	 * calling convention and feature set
	 *
	 * @param $table string
	 * @param $var
	 * @param $value
	 * @param $cond
	 * @param $fname string
	 *
	 * @return bool
	 */
	function set( $table, $var, $value, $cond, $fname = 'DatabaseBase::set' ) {
		$table = $this->tableName( $table );
		$sql = "UPDATE $table SET $var = '" .
		  $this->strencode( $value ) . "' WHERE ($cond)";

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

	/**
	 * A SELECT wrapper which returns a single field from a single result row.
	 *
	 * Usually throws a DBQueryError on failure. If errors are explicitly
	 * ignored, returns false on failure.
	 *
	 * If no result rows are returned from the query, false is returned.
	 *
	 * @param $table string|array Table name. See DatabaseBase::select() for details.
	 * @param $var string The field name to select. This must be a valid SQL
	 *   fragment: do not use unvalidated user input.
	 * @param $cond string|array The condition array. See DatabaseBase::select() for details.
	 * @param $fname string The function name of the caller.
	 * @param $options string|array The query options. See DatabaseBase::select() for details.
	 *
	 * @return false|mixed The value from the field, or false on failure.
	 */
	function selectField( $table, $var, $cond = '', $fname = 'DatabaseBase::selectField',
		$options = array() )
	{
		if ( !is_array( $options ) ) {
			$options = array( $options );
		}

		$options['LIMIT'] = 1;

		$res = $this->select( $table, $var, $cond, $fname, $options );

		if ( $res === false || !$this->numRows( $res ) ) {
			return false;
		}

		$row = $this->fetchRow( $res );

		if ( $row !== false ) {
			return reset( $row );
		} else {
			return false;
		}
	}

	/**
	 * Returns an optional USE INDEX clause to go after the table, and a
	 * string to go at the end of the query.
	 *
	 * @param $options Array: associative array of options to be turned into
	 *              an SQL query, valid keys are listed in the function.
	 * @return Array
	 * @see DatabaseBase::select()
	 */
	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'] ) ) {
			$gb = is_array( $options['GROUP BY'] )
				? implode( ',', $options['GROUP BY'] )
				: $options['GROUP BY'];
			$preLimitTail .= " GROUP BY {$gb}";
		}

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

		if ( isset( $options['ORDER BY'] ) ) {
			$ob = is_array( $options['ORDER BY'] )
				? implode( ',', $options['ORDER BY'] )
				: $options['ORDER BY'];
			$preLimitTail .= " ORDER BY {$ob}";
		}

		// if (isset($options['LIMIT'])) {
		//	$tailOpts .= $this->limitResult('', $options['LIMIT'],
		//		isset($options['OFFSET']) ? $options['OFFSET']
		//		: false);
		// }

		if ( isset( $noKeyOptions['FOR UPDATE'] ) ) {
			$postLimitTail .= ' FOR UPDATE';
		}

		if ( isset( $noKeyOptions['LOCK IN SHARE MODE'] ) ) {
			$postLimitTail .= ' LOCK IN SHARE MODE';
		}

		if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
			$startOpts .= 'DISTINCT';
		}

		# Various MySQL extensions
		if ( isset( $noKeyOptions['STRAIGHT_JOIN'] ) ) {
			$startOpts .= ' /*! STRAIGHT_JOIN */';
		}

		if ( isset( $noKeyOptions['HIGH_PRIORITY'] ) ) {
			$startOpts .= ' HIGH_PRIORITY';
		}

		if ( isset( $noKeyOptions['SQL_BIG_RESULT'] ) ) {
			$startOpts .= ' SQL_BIG_RESULT';
		}

		if ( isset( $noKeyOptions['SQL_BUFFER_RESULT'] ) ) {
			$startOpts .= ' SQL_BUFFER_RESULT';
		}

		if ( isset( $noKeyOptions['SQL_SMALL_RESULT'] ) ) {
			$startOpts .= ' SQL_SMALL_RESULT';
		}

		if ( isset( $noKeyOptions['SQL_CALC_FOUND_ROWS'] ) ) {
			$startOpts .= ' SQL_CALC_FOUND_ROWS';
		}

		if ( isset( $noKeyOptions['SQL_CACHE'] ) ) {
			$startOpts .= ' SQL_CACHE';
		}

		if ( isset( $noKeyOptions['SQL_NO_CACHE'] ) ) {
			$startOpts .= ' SQL_NO_CACHE';
		}

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

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

	/**
	 * Execute a SELECT query constructed using the various parameters provided.
	 * See below for full details of the parameters.
	 *
	 * @param $table String|Array Table name
	 * @param $vars String|Array Field names
	 * @param $conds String|Array Conditions
	 * @param $fname String Caller function name
	 * @param $options Array Query options
	 * @param $join_conds Array Join conditions
	 *
	 * @param $table string|array
	 *
	 * May be either an array of table names, or a single string holding a table
	 * name. If an array is given, table aliases can be specified, for example:
	 *
	 *    array( 'a' => 'user' )
	 *
	 * This includes the user table in the query, with the alias "a" available
	 * for use in field names (e.g. a.user_name).
	 *
	 * All of the table names given here are automatically run through
	 * DatabaseBase::tableName(), which causes the table prefix (if any) to be
	 * added, and various other table name mappings to be performed.
	 *
	 *
	 * @param $vars string|array
	 *
	 * May be either a field name or an array of field names. The field names
	 * here are complete fragments of SQL, for direct inclusion into the SELECT
	 * query. Expressions and aliases may be specified as in SQL, for example:
	 *
	 *   array( 'MAX(rev_id) AS maxrev' )
	 *
	 * If an expression is given, care must be taken to ensure that it is
	 * DBMS-independent.
	 *
	 *
	 * @param $conds string|array
	 *
	 * May be either a string containing a single condition, or an array of
	 * conditions. If an array is given, the conditions constructed from each
	 * element are combined with AND.
	 *
	 * Array elements may take one of two forms:
	 *
	 *   - Elements with a numeric key are interpreted as raw SQL fragments.
	 *   - Elements with a string key are interpreted as equality conditions,
	 *     where the key is the field name.
	 *     - If the value of such an array element is a scalar (such as a
	 *       string), it will be treated as data and thus quoted appropriately.
	 *       If it is null, an IS NULL clause will be added.
	 *     - If the value is an array, an IN(...) clause will be constructed,
	 *       such that the field name may match any of the elements in the
	 *       array. The elements of the array will be quoted.
	 *
	 * Note that expressions are often DBMS-dependent in their syntax.
	 * DBMS-independent wrappers are provided for constructing several types of
	 * expression commonly used in condition queries. See:
	 *    - DatabaseBase::buildLike()
	 *    - DatabaseBase::conditional()
	 *
	 *
	 * @param $options string|array
	 *
	 * Optional: Array of query options. Boolean options are specified by
	 * including them in the array as a string value with a numeric key, for
	 * example:
	 *
	 *    array( 'FOR UPDATE' )
	 *
	 * The supported options are:
	 *
	 *   - OFFSET: Skip this many rows at the start of the result set. OFFSET
	 *     with LIMIT can theoretically be used for paging through a result set,
	 *     but this is discouraged in MediaWiki for performance reasons.
	 *
	 *   - LIMIT: Integer: return at most this many rows. The rows are sorted
	 *     and then the first rows are taken until the limit is reached. LIMIT
	 *     is applied to a result set after OFFSET.
	 *
	 *   - FOR UPDATE: Boolean: lock the returned rows so that they can't be
	 *     changed until the next COMMIT.
	 *
	 *   - DISTINCT: Boolean: return only unique result rows.
	 *
	 *   - GROUP BY: May be either an SQL fragment string naming a field or
	 *     expression to group by, or an array of such SQL fragments.
	 *
	 *   - HAVING: A string containing a HAVING clause.
	 *
	 *   - ORDER BY: May be either an SQL fragment giving a field name or
	 *     expression to order by, or an array of such SQL fragments.
	 *
	 *   - USE INDEX: This may be either a string giving the index name to use
	 *     for the query, or an array. If it is an associative array, each key
	 *     gives the table name (or alias), each value gives the index name to
	 *     use for that table. All strings are SQL fragments and so should be
	 *     validated by the caller.
	 *
	 *   - EXPLAIN: In MySQL, this causes an EXPLAIN SELECT query to be run,
	 *     instead of SELECT.
	 *
	 * And also the following boolean MySQL extensions, see the MySQL manual
	 * for documentation:
	 *
	 *    - LOCK IN SHARE MODE
	 *    - STRAIGHT_JOIN
	 *    - HIGH_PRIORITY
	 *    - SQL_BIG_RESULT
	 *    - SQL_BUFFER_RESULT
	 *    - SQL_SMALL_RESULT
	 *    - SQL_CALC_FOUND_ROWS
	 *    - SQL_CACHE
	 *    - SQL_NO_CACHE
	 *
	 *
	 * @param $join_conds string|array
	 *
	 * Optional associative array of table-specific join conditions. In the
	 * most common case, this is unnecessary, since the join condition can be
	 * in $conds. However, it is useful for doing a LEFT JOIN.
	 *
	 * The key of the array contains the table name or alias. The value is an
	 * array with two elements, numbered 0 and 1. The first gives the type of
	 * join, the second is an SQL fragment giving the join condition for that
	 * table. For example:
	 *
	 *    array( 'page' => array('LEFT JOIN','page_latest=rev_id') )
	 *
	 * @return ResultWrapper. If the query returned no rows, a ResultWrapper
	 *   with no rows in it will be returned. If there was a query error, a
	 *   DBQueryError exception will be thrown, except if the "ignore errors"
	 *   option was set, in which case false will be returned.
	 */
	function select( $table, $vars, $conds = '', $fname = 'DatabaseBase::select',
		$options = array(), $join_conds = array() ) {
		$sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );

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

	/**
	 * The equivalent of DatabaseBase::select() except that the constructed SQL
	 * is returned, instead of being immediately executed.
	 *
	 * @param $table string|array Table name
	 * @param $vars string|array Field names
	 * @param $conds string|array Conditions
	 * @param $fname string Caller function name
	 * @param $options string|array Query options
	 * @param $join_conds string|array Join conditions
	 *
	 * @return SQL query string.
	 * @see DatabaseBase::select()
	 */
	function selectSQLText( $table, $vars, $conds = '', $fname = 'DatabaseBase::select', $options = array(), $join_conds = array() ) {
		if ( is_array( $vars ) ) {
			$vars = implode( ',', $vars );
		}

		$options = (array)$options;

		if ( is_array( $table ) ) {
			$useIndex = ( isset( $options['USE INDEX'] ) && is_array( $options['USE INDEX'] ) )
				? $options['USE INDEX']
				: array();
			if ( count( $join_conds ) || count( $useIndex ) ) {
				$from = ' FROM ' .
					$this->tableNamesWithUseIndexOrJOIN( $table, $useIndex, $join_conds );
			} else {
				$from = ' FROM ' . implode( ',', $this->tableNamesWithAlias( $table ) );
			}
		} elseif ( $table != '' ) {
			if ( $table[0] == ' ' ) {
				$from = ' FROM ' . $table;
			} else {
				$from = ' FROM ' . $this->tableName( $table );
			}
		} else {
			$from = '';
		}

		list( $startOpts, $useIndex, $preLimitTail, $postLimitTail ) = $this->makeSelectOptions( $options );

		if ( !empty( $conds ) ) {
			if ( is_array( $conds ) ) {
				$conds = $this->makeList( $conds, LIST_AND );
			}
			$sql = "SELECT $startOpts $vars $from $useIndex WHERE $conds $preLimitTail";
		} else {
			$sql = "SELECT $startOpts $vars $from $useIndex $preLimitTail";
		}

		if ( isset( $options['LIMIT'] ) ) {
			$sql = $this->limitResult( $sql, $options['LIMIT'],
				isset( $options['OFFSET'] ) ? $options['OFFSET'] : false );
		}
		$sql = "$sql $postLimitTail";

		if ( isset( $options['EXPLAIN'] ) ) {
			$sql = 'EXPLAIN ' . $sql;
		}

		return $sql;
	}

	/**
	 * Single row SELECT wrapper. Equivalent to DatabaseBase::select(), except
	 * that a single row object is returned. If the query returns no rows,
	 * false is returned.
	 *
	 * @param $table string|array Table name
	 * @param $vars string|array Field names
	 * @param $conds array Conditions
	 * @param $fname string Caller function name
	 * @param $options string|array Query options
	 * @param $join_conds array|string Join conditions
	 *
	 * @return ResultWrapper|bool
	 */
	function selectRow( $table, $vars, $conds, $fname = 'DatabaseBase::selectRow',
		$options = array(), $join_conds = array() )
	{
		$options = (array)$options;
		$options['LIMIT'] = 1;
		$res = $this->select( $table, $vars, $conds, $fname, $options, $join_conds );

		if ( $res === false ) {
			return false;
		}

		if ( !$this->numRows( $res ) ) {
			return false;
		}

		$obj = $this->fetchObject( $res );

		return $obj;
	}

	/**
	 * Estimate rows in dataset.
	 *
	 * MySQL allows you to estimate the number of rows that would be returned
	 * by a SELECT query, using EXPLAIN SELECT. The estimate is provided using
	 * index cardinality statistics, and is notoriously inaccurate, especially
	 * when large numbers of rows have recently been added or deleted.
	 *
	 * For DBMSs that don't support fast result size estimation, this function
	 * will actually perform the SELECT COUNT(*).
	 *
	 * Takes the same arguments as DatabaseBase::select().
	 *
	 * @param $table String: table name
	 * @param Array|string $vars : unused
	 * @param Array|string $conds : filters on the table
	 * @param $fname String: function name for profiling
	 * @param $options Array: options for select
	 * @return Integer: row count
	 */
	public function estimateRowCount( $table, $vars = '*', $conds = '',
		$fname = 'DatabaseBase::estimateRowCount', $options = array() )
	{
		$rows = 0;
		$res = $this->select ( $table, 'COUNT(*) AS rowcount', $conds, $fname, $options );

		if ( $res ) {
			$row = $this->fetchRow( $res );
			$rows = ( isset( $row['rowcount'] ) ) ? $row['rowcount'] : 0;
		}

		return $rows;
	}

	/**
	 * Removes most variables from an SQL query and replaces them with X or N for numbers.
	 * It's only slightly flawed. Don't use for anything important.
	 *
	 * @param $sql String A SQL Query
	 *
	 * @return string
	 */
	static function generalizeSQL( $sql ) {
		# This does the same as the regexp below would do, but in such a way
		# as to avoid crashing php on some large strings.
		# $sql = preg_replace ( "/'([^\\\\']|\\\\.)*'|\"([^\\\\\"]|\\\\.)*\"/", "'X'", $sql);

		$sql = str_replace ( "\\\\", '', $sql );
		$sql = str_replace ( "\\'", '', $sql );
		$sql = str_replace ( "\\\"", '', $sql );
		$sql = preg_replace ( "/'.*'/s", "'X'", $sql );
		$sql = preg_replace ( '/".*"/s', "'X'", $sql );

		# All newlines, tabs, etc replaced by single space
		$sql = preg_replace ( '/\s+/', ' ', $sql );

		# All numbers => N
		$sql = preg_replace ( '/-?[0-9]+/s', 'N', $sql );

		return $sql;
	}

	/**
	 * Determines whether a field exists in a table
	 *
	 * @param $table String: table name
	 * @param $field String: filed to check on that table
	 * @param $fname String: calling function name (optional)
	 * @return Boolean: whether $table has filed $field
	 */
	function fieldExists( $table, $field, $fname = 'DatabaseBase::fieldExists' ) {
		$info = $this->fieldInfo( $table, $field );

		return (bool)$info;
	}

	/**
	 * Determines whether an index exists
	 * Usually throws a DBQueryError on failure
	 * If errors are explicitly ignored, returns NULL on failure
	 *
	 * @param $table
	 * @param $index
	 * @param $fname string
	 *
	 * @return bool|null
	 */
	function indexExists( $table, $index, $fname = 'DatabaseBase::indexExists' ) {
		$info = $this->indexInfo( $table, $index, $fname );
		if ( is_null( $info ) ) {
			return null;
		} else {
			return $info !== false;
		}
	}

	/**
	 * Query whether a given table exists
	 *
	 * @param $table string
	 * @param $fname string
	 *
	 * @return bool
	 */
	function tableExists( $table, $fname = __METHOD__ ) {
		$table = $this->tableName( $table );
		$old = $this->ignoreErrors( true );
		$res = $this->query( "SELECT 1 FROM $table LIMIT 1", $fname );
		$this->ignoreErrors( $old );

		return (bool)$res;
	}

	/**
	 * mysql_field_type() wrapper
	 * @param $res
	 * @param $index
	 * @return string
	 */
	function fieldType( $res, $index ) {
		if ( $res instanceof ResultWrapper ) {
			$res = $res->result;
		}

		return mysql_field_type( $res, $index );
	}

	/**
	 * Determines if a given index is unique
	 *
	 * @param $table string
	 * @param $index string
	 *
	 * @return bool
	 */
	function indexUnique( $table, $index ) {
		$indexInfo = $this->indexInfo( $table, $index );

		if ( !$indexInfo ) {
			return null;
		}

		return !$indexInfo[0]->Non_unique;
	}

	/**
	 * Helper for DatabaseBase::insert().
	 *
	 * @param $options array
	 * @return string
	 */
	function makeInsertOptions( $options ) {
		return implode( ' ', $options );
	}

	/**
	 * INSERT wrapper, inserts an array into a table.
	 *
	 * $a may be either:
	 *
	 *   - A single associative array. The array keys are the field names, and
	 *     the values are the values to insert. The values are treated as data
	 *     and will be quoted appropriately. If NULL is inserted, this will be
	 *     converted to a database NULL.
	 *   - An array with numeric keys, holding a list of associative arrays.
	 *     This causes a multi-row INSERT on DBMSs that support it. The keys in
	 *     each subarray must be identical to each other, and in the same order.
	 *
	 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
	 * returns success.
	 *
	 * $options is an array of options, with boolean options encoded as values
	 * with numeric keys, in the same style as $options in
	 * DatabaseBase::select(). Supported options are:
	 *
	 *   - IGNORE: Boolean: if present, duplicate key errors are ignored, and
	 *     any rows which cause duplicate key errors are not inserted. It's
	 *     possible to determine how many rows were successfully inserted using
	 *     DatabaseBase::affectedRows().
	 *
	 * @param $table   String Table name. This will be passed through
	 *                 DatabaseBase::tableName().
	 * @param $a       Array of rows to insert
	 * @param $fname   String Calling function name (use __METHOD__) for logs/profiling
	 * @param $options Array of options
	 *
	 * @return bool
	 */
	function insert( $table, $a, $fname = 'DatabaseBase::insert', $options = array() ) {
		# No rows to insert, easy just return now
		if ( !count( $a ) ) {
			return true;
		}

		$table = $this->tableName( $table );

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

		$options = $this->makeInsertOptions( $options );

		if ( isset( $a[0] ) && is_array( $a[0] ) ) {
			$multi = true;
			$keys = array_keys( $a[0] );
		} else {
			$multi = false;
			$keys = array_keys( $a );
		}

		$sql = 'INSERT ' . $options .
			" INTO $table (" . implode( ',', $keys ) . ') VALUES ';

		if ( $multi ) {
			$first = true;
			foreach ( $a as $row ) {
				if ( $first ) {
					$first = false;
				} else {
					$sql .= ',';
				}
				$sql .= '(' . $this->makeList( $row ) . ')';
			}
		} else {
			$sql .= '(' . $this->makeList( $a ) . ')';
		}

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

	/**
	 * Make UPDATE options for the DatabaseBase::update function
	 *
	 * @param $options Array: The options passed to DatabaseBase::update
	 * @return string
	 */
	function makeUpdateOptions( $options ) {
		if ( !is_array( $options ) ) {
			$options = array( $options );
		}

		$opts = array();

		if ( in_array( 'LOW_PRIORITY', $options ) ) {
			$opts[] = $this->lowPriorityOption();
		}

		if ( in_array( 'IGNORE', $options ) ) {
			$opts[] = 'IGNORE';
		}

		return implode( ' ', $opts );
	}

	/**
	 * UPDATE wrapper. Takes a condition array and a SET array.
	 *
	 * @param $table  String name of the table to UPDATE. This will be passed through
	 *                DatabaseBase::tableName().
	 *
	 * @param $values Array:  An array of values to SET. For each array element,
	 *                the key gives the field name, and the value gives the data
	 *                to set that field to. The data will be quoted by
	 *                DatabaseBase::addQuotes().
	 *
	 * @param $conds  Array:  An array of conditions (WHERE). See
	 *                DatabaseBase::select() for the details of the format of
	 *                condition arrays. Use '*' to update all rows…