Update to MediaWiki 1.26.0

16 files changed, 2548 insertions, 474 deletions

diff --git a/includes/db/DBConnRef.php b/includes/db/DBConnRef.php
new file mode 100644
index 00000000..b4f3f792
--- /dev/null
+++ b/includes/db/DBConnRef.php
@@ -0,0 +1,524 @@
+<?php
+/**
+ * Helper class to handle automatically marking connections as reusable (via RAII pattern)
+ * as well handling deferring the actual network connection until the handle is used
+ *
+ * @note: proxy methods are defined explicity to avoid interface errors
+ * @ingroup Database
+ * @since 1.22
+ */
+class DBConnRef implements IDatabase {
+	/** @var LoadBalancer */
+	private $lb;
+
+	/** @var DatabaseBase|null */
+	private $conn;
+
+	/** @var array|null */
+	private $params;
+
+	/**
+	 * @param LoadBalancer $lb
+	 * @param DatabaseBase|array $conn Connection or (server index, group, wiki ID) array
+	 */
+	public function __construct( LoadBalancer $lb, $conn ) {
+		$this->lb = $lb;
+		if ( $conn instanceof DatabaseBase ) {
+			$this->conn = $conn;
+		} else {
+			$this->params = $conn;
+		}
+	}
+
+	function __call( $name, array $arguments ) {
+		if ( $this->conn === null ) {
+			list( $db, $groups, $wiki ) = $this->params;
+			$this->conn = $this->lb->getConnection( $db, $groups, $wiki );
+		}
+
+		return call_user_func_array( array( $this->conn, $name ), $arguments );
+	}
+
+	public function getServerInfo() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function bufferResults( $buffer = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function trxLevel() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function trxTimestamp() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function tablePrefix( $prefix = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function dbSchema( $schema = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getLBInfo( $name = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function setLBInfo( $name, $value = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function implicitGroupby() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function implicitOrderby() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lastQuery() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function doneWrites() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lastDoneWrites() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function writesOrCallbacksPending() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function pendingWriteQueryDuration() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function isOpen() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function setFlag( $flag ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function clearFlag( $flag ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getFlag( $flag ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getProperty( $name ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getWikiID() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getType() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function open( $server, $user, $password, $dbName ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function fetchObject( $res ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function fetchRow( $res ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function numRows( $res ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function numFields( $res ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function fieldName( $res, $n ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function insertId() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function dataSeek( $res, $row ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lastErrno() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lastError() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function fieldInfo( $table, $field ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function affectedRows() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getSoftwareLink() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getServerVersion() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function close() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function reportConnectionError( $error = 'Unknown error' ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function query( $sql, $fname = __METHOD__, $tempIgnore = false ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function freeResult( $res ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectField(
+		$table, $var, $cond = '', $fname = __METHOD__, $options = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectFieldValues(
+		$table, $var, $cond = '', $fname = __METHOD__, $options = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function select(
+		$table, $vars, $conds = '', $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectSQLText(
+		$table, $vars, $conds = '', $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectRow(
+		$table, $vars, $conds, $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function estimateRowCount(
+		$table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectRowCount(
+		$table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function fieldExists( $table, $field, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function indexExists( $table, $index, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function tableExists( $table, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function indexUnique( $table, $index ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function update( $table, $values, $conds, $fname = __METHOD__, $options = array() ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function makeList( $a, $mode = LIST_COMMA ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function makeWhereFrom2d( $data, $baseKey, $subKey ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function bitNot( $field ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function bitAnd( $fieldLeft, $fieldRight ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function bitOr( $fieldLeft, $fieldRight ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function buildConcat( $stringList ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function buildGroupConcatField(
+		$delim, $table, $field, $conds = '', $join_conds = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function selectDB( $db ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getDBname() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getServer() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function addQuotes( $s ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function buildLike() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function anyChar() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function anyString() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function nextSequenceValue( $seqName ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function upsert(
+		$table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function deleteJoin(
+		$delTable, $joinTable, $delVar, $joinVar, $conds, $fname = __METHOD__
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function delete( $table, $conds, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function insertSelect(
+		$destTable, $srcTable, $varMap, $conds,
+		$fname = __METHOD__, $insertOptions = array(), $selectOptions = array()
+	) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function unionSupportsOrderAndLimit() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function unionQueries( $sqls, $all ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function conditional( $cond, $trueVal, $falseVal ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function strreplace( $orig, $old, $new ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getServerUptime() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function wasDeadlock() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function wasLockTimeout() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function wasErrorReissuable() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function wasReadOnlyError() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function masterPosWait( DBMasterPos $pos, $timeout ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getSlavePos() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getMasterPos() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function onTransactionIdle( $callback ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function onTransactionPreCommitOrIdle( $callback ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function startAtomic( $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function endAtomic( $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function begin( $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function commit( $fname = __METHOD__, $flush = '' ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function rollback( $fname = __METHOD__, $flush = '' ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function listTables( $prefix = null, $fname = __METHOD__ ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function timestamp( $ts = 0 ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function timestampOrNull( $ts = null ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function resultObject( $result ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function ping() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getLag() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function maxListLen() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function encodeBlob( $b ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function decodeBlob( $b ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function setSessionOptions( array $options ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function setSchemaVars( $vars ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lockIsFree( $lockName, $method ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function lock( $lockName, $method, $timeout = 5 ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function unlock( $lockName, $method ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function namedLocksEnqueue() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function getInfinity() {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function encodeExpiry( $expiry ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function decodeExpiry( $expiry, $format = TS_MW ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	public function setBigSelects( $value = true ) {
+		return $this->__call( __FUNCTION__, func_get_args() );
+	}
+
+	/**
+	 * Clean up the connection when out of scope
+	 */
+	function __destruct() {
+		if ( $this->conn !== null ) {
+			$this->lb->reuseConnection( $this->conn );
+		}
+	}
+}
diff --git a/includes/db/Database.php b/includes/db/Database.php
index 0c0248da..1e54f554 100644
--- a/includes/db/Database.php
+++ b/includes/db/Database.php
@@ -26,13 +26,6 @@
  */
 
 /**
- * Interface for classes that implement or wrap DatabaseBase
- * @ingroup Database
- */
-interface IDatabase {
-}
-
-/**
  * Database abstraction object
  * @ingroup Database
  */
@@ -65,10 +58,11 @@ abstract class DatabaseBase implements IDatabase {
 	protected $mSchema;
 	protected $mFlags;
 	protected $mForeign;
-	protected $mErrorCount = 0;
 	protected $mLBInfo = array();
 	protected $mDefaultBigSelects = null;
 	protected $mSchemaVars = false;
+	/** @var array */
+	protected $mSessionVars = array();
 
 	protected $preparedArgs;
 
@@ -142,6 +136,13 @@ abstract class DatabaseBase implements IDatabase {
 	private $mTrxAutomaticAtomic = false;
 
 	/**
+	 * Track the seconds spent in write queries for the current transaction
+	 *
+	 * @var float
+	 */
+	private $mTrxWriteDuration = 0.0;
+
+	/**
 	 * @since 1.21
 	 * @var resource File handle for upgrade
 	 */
@@ -228,7 +229,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param null|bool $ignoreErrors
 	 * @return bool The previous value of the flag.
 	 */
-	public function ignoreErrors( $ignoreErrors = null ) {
+	protected function ignoreErrors( $ignoreErrors = null ) {
 		return wfSetBit( $this->mFlags, DBO_IGNORE, $ignoreErrors );
 	}
 
@@ -258,15 +259,6 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
-	 * Get/set the number of errors logged. Only useful when errors are ignored
-	 * @param int $count The count to set, or omitted to leave it unchanged.
-	 * @return int The error count
-	 */
-	public function errorCount( $count = null ) {
-		return wfSetVar( $this->mErrorCount, $count );
-	}
-
-	/**
 	 * Get/set the table prefix.
 	 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
 	 * @return string The previous table prefix.
@@ -474,6 +466,18 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
+	 * Get the time spend running write queries for this
+	 *
+	 * High times could be due to scanning, updates, locking, and such
+	 *
+	 * @return float|bool Returns false if not transaction is active
+	 * @since 1.26
+	 */
+	public function pendingWriteQueryDuration() {
+		return $this->mTrxLevel ? $this->mTrxWriteDuration : false;
+	}
+
+	/**
 	 * Is a connection to the database open?
 	 * @return bool
 	 */
@@ -592,125 +596,6 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
-	 * Get the type of the DBMS, as it appears in $wgDBtype.
-	 *
-	 * @return string
-	 */
-	abstract function getType();
-
-	/**
-	 * Open a connection to the database. Usually aborts on failure
-	 *
-	 * @param string $server Database server host
-	 * @param string $user Database user name
-	 * @param string $password Database user password
-	 * @param string $dbName Database name
-	 * @return bool
-	 * @throws DBConnectionError
-	 */
-	abstract 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.
-	 * If no more rows are available, false is returned.
-	 *
-	 * @param ResultWrapper|stdClass $res Object as returned from DatabaseBase::query(), etc.
-	 * @return stdClass|bool
-	 * @throws DBUnexpectedError Thrown if the database returns an error
-	 */
-	abstract function fetchObject( $res );
-
-	/**
-	 * Fetch the next row from the given result object, in associative array
-	 * form. Fields are retrieved with $row['fieldname'].
-	 * If no more rows are available, false is returned.
-	 *
-	 * @param ResultWrapper $res Result object as returned from DatabaseBase::query(), etc.
-	 * @return array|bool
-	 * @throws DBUnexpectedError Thrown if the database returns an error
-	 */
-	abstract function fetchRow( $res );
-
-	/**
-	 * Get the number of rows in a result object
-	 *
-	 * @param mixed $res A SQL result
-	 * @return int
-	 */
-	abstract function numRows( $res );
-
-	/**
-	 * Get the number of fields in a result object
-	 * @see http://www.php.net/mysql_num_fields
-	 *
-	 * @param mixed $res A SQL result
-	 * @return int
-	 */
-	abstract function numFields( $res );
-
-	/**
-	 * Get a field name in a result object
-	 * @see http://www.php.net/mysql_field_name
-	 *
-	 * @param mixed $res A SQL result
-	 * @param int $n
-	 * @return string
-	 */
-	abstract 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
-	 */
-	abstract function insertId();
-
-	/**
-	 * Change the position of the cursor in a result object
-	 * @see http://www.php.net/mysql_data_seek
-	 *
-	 * @param mixed $res A SQL result
-	 * @param int $row
-	 */
-	abstract function dataSeek( $res, $row );
-
-	/**
-	 * Get the last error number
-	 * @see http://www.php.net/mysql_errno
-	 *
-	 * @return int
-	 */
-	abstract function lastErrno();
-
-	/**
-	 * Get a description of the last error
-	 * @see http://www.php.net/mysql_error
-	 *
-	 * @return string
-	 */
-	abstract function lastError();
-
-	/**
-	 * mysql_fetch_field() wrapper
-	 * Returns false if the field doesn't exist
-	 *
-	 * @param string $table Table name
-	 * @param string $field Field name
-	 *
-	 * @return Field
-	 */
-	abstract function fieldInfo( $table, $field );
-
-	/**
 	 * Get information about an index into an object
 	 * @param string $table Table name
 	 * @param string $index Index name
@@ -720,14 +605,6 @@ abstract class DatabaseBase implements IDatabase {
 	abstract function indexInfo( $table, $index, $fname = __METHOD__ );
 
 	/**
-	 * Get the number of rows affected by the last write query
-	 * @see http://www.php.net/mysql_affected_rows
-	 *
-	 * @return int
-	 */
-	abstract function affectedRows();
-
-	/**
 	 * Wrapper for addslashes()
 	 *
 	 * @param string $s String to be slashed.
@@ -736,24 +613,6 @@ abstract class DatabaseBase implements IDatabase {
 	abstract 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
-	 */
-	abstract function getSoftwareLink();
-
-	/**
-	 * A string describing the current software version, like from
-	 * mysql_get_server_info().
-	 *
-	 * @return string Version information from the database server.
-	 */
-	abstract function getServerVersion();
-
-	/**
 	 * Constructor.
 	 *
 	 * FIXME: It is possible to construct a Database object with no associated
@@ -794,15 +653,17 @@ abstract class DatabaseBase implements IDatabase {
 			}
 		}
 
+		$this->mSessionVars = $params['variables'];
+
 		/** Get the default table prefix*/
-		if ( $tablePrefix == 'get from global' ) {
+		if ( $tablePrefix === 'get from global' ) {
 			$this->mTablePrefix = $wgDBprefix;
 		} else {
 			$this->mTablePrefix = $tablePrefix;
 		}
 
 		/** Get the database schema*/
-		if ( $schema == 'get from global' ) {
+		if ( $schema === 'get from global' ) {
 			$this->mSchema = $wgDBmwschema;
 		} else {
 			$this->mSchema = $schema;
@@ -892,10 +753,6 @@ abstract class DatabaseBase implements IDatabase {
 		// Although postgres and oracle support schemas, we don't use them (yet)
 		// to maintain backwards compatibility
 		$defaultSchemas = array(
-			'mysql' => null,
-			'postgres' => null,
-			'sqlite' => null,
-			'oracle' => null,
 			'mssql' => 'get from global',
 		);
 
@@ -907,8 +764,11 @@ abstract class DatabaseBase implements IDatabase {
 			$p['password'] = isset( $p['password'] ) ? $p['password'] : false;
 			$p['dbname'] = isset( $p['dbname'] ) ? $p['dbname'] : false;
 			$p['flags'] = isset( $p['flags'] ) ? $p['flags'] : 0;
+			$p['variables'] = isset( $p['variables'] ) ? $p['variables'] : array();
 			$p['tablePrefix'] = isset( $p['tablePrefix'] ) ? $p['tablePrefix'] : 'get from global';
-			$p['schema'] = isset( $p['schema'] ) ? $p['schema'] : $defaultSchemas[$dbType];
+			if ( !isset( $p['schema'] ) ) {
+				$p['schema'] = isset( $defaultSchemas[$dbType] ) ? $defaultSchemas[$dbType] : null;
+			}
 			$p['foreign'] = isset( $p['foreign'] ) ? $p['foreign'] : false;
 
 			return new $class( $p );
@@ -998,6 +858,17 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
+	 * Make sure isOpen() returns true as a sanity check
+	 *
+	 * @throws DBUnexpectedError
+	 */
+	protected function assertOpen() {
+		if ( !$this->isOpen() ) {
+			throw new DBUnexpectedError( $this, "DB connection was already closed." );
+		}
+	}
+
+	/**
 	 * Closes underlying database connection
 	 * @since 1.20
 	 * @return bool Whether connection was closed successfully
@@ -1034,7 +905,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string $sql
 	 * @return bool
 	 */
-	public function isWriteQuery( $sql ) {
+	protected function isWriteQuery( $sql ) {
 		return !preg_match( '/^(?:SELECT|BEGIN|ROLLBACK|COMMIT|SET|SHOW|EXPLAIN|\(SELECT)\b/i', $sql );
 	}
 
@@ -1047,7 +918,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string $sql
 	 * @return bool
 	 */
-	public function isTransactableQuery( $sql ) {
+	protected function isTransactableQuery( $sql ) {
 		$verb = substr( $sql, 0, strcspn( $sql, " \t\r\n" ) );
 		return !in_array( $verb, array( 'BEGIN', 'COMMIT', 'ROLLBACK', 'SHOW', 'SET' ) );
 	}
@@ -1153,13 +1024,12 @@ abstract class DatabaseBase implements IDatabase {
 		$queryId = MWDebug::query( $sql, $fname, $isMaster );
 
 		# Avoid fatals if close() was called
-		if ( !$this->isOpen() ) {
-			throw new DBUnexpectedError( $this, "DB connection was already closed." );
-		}
+		$this->assertOpen();
 
 		# Do the query and handle errors
 		$startTime = microtime( true );
 		$ret = $this->doQuery( $commentedSql );
+		$queryRuntime = microtime( true ) - $startTime;
 		# Log the query time and feed it into the DB trx profiler
 		$this->getTransactionProfiler()->recordQueryCompletion(
 			$queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
@@ -1191,6 +1061,7 @@ abstract class DatabaseBase implements IDatabase {
 					# Should be safe to silently retry (no trx and thus no callbacks)
 					$startTime = microtime( true );
 					$ret = $this->doQuery( $commentedSql );
+					$queryRuntime = microtime( true ) - $startTime;
 					# Log the query time and feed it into the DB trx profiler
 					$this->getTransactionProfiler()->recordQueryCompletion(
 						$queryProf, $startTime, $isWriteQuery, $this->affectedRows() );
@@ -1211,6 +1082,10 @@ abstract class DatabaseBase implements IDatabase {
 		$queryProfSection = false;
 		$totalProfSection = false;
 
+		if ( $isWriteQuery && $this->mTrxLevel ) {
+			$this->mTrxWriteDuration += $queryRuntime;
+		}
+
 		return $res;
 	}
 
@@ -1226,8 +1101,6 @@ abstract class DatabaseBase implements IDatabase {
 	 * @throws DBQueryError
 	 */
 	public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false ) {
-		++$this->mErrorCount;
-
 		if ( $this->ignoreErrors() || $tempIgnore ) {
 			wfDebug( "SQL ERROR (ignored): $error\n" );
 		} else {
@@ -1421,6 +1294,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string|array $options The query options. See DatabaseBase::select() for details.
 	 *
 	 * @return bool|array The values from the field, or false on failure
+	 * @throws DBUnexpectedError
 	 * @since 1.25
 	 */
 	public function selectFieldValues(
@@ -1881,7 +1755,7 @@ abstract class DatabaseBase implements IDatabase {
 	) {
 		$rows = 0;
 		$sql = $this->selectSQLText( $table, '1', $conds, $fname, $options );
-		$res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count" );
+		$res = $this->query( "SELECT COUNT(*) AS rowcount FROM ($sql) tmp_count", $fname );
 
 		if ( $res ) {
 			$row = $this->fetchRow( $res );
@@ -2015,9 +1889,6 @@ abstract class DatabaseBase implements IDatabase {
 	 *     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:
@@ -2033,6 +1904,9 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 	 * @param array $options Array of options
 	 *
+	 * @throws DBQueryError Usually throws a DBQueryError on failure. If errors are explicitly ignored,
+	 * returns success.
+	 *
 	 * @return bool
 	 */
 	public function insert( $table, $a, $fname = __METHOD__, $options = array() ) {
@@ -2455,7 +2329,7 @@ abstract class DatabaseBase implements IDatabase {
 		}
 
 		# Quote $schema and merge it with the table name if needed
-		if ( $schema !== null ) {
+		if ( strlen( $schema ) ) {
 			if ( $format == 'quoted' && !$this->isQuotedIdentifier( $schema ) ) {
 				$schema = $this->addIdentifierQuotes( $schema );
 			}
@@ -2842,6 +2716,7 @@ abstract class DatabaseBase implements IDatabase {
 			$rows = array( $rows );
 		}
 
+		// @FXIME: this is not atomic, but a trx would break affectedRows()
 		foreach ( $rows as $row ) {
 			# Delete rows which collide
 			if ( $uniqueIndexes ) {
@@ -3303,6 +3178,17 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
+	 * Determines if the given query error was a connection drop
+	 * STUB
+	 *
+	 * @param integer|string $errno
+	 * @return bool
+	 */
+	public function wasConnectionError( $errno ) {
+		return false;
+	}
+
+	/**
 	 * Perform a deadlock-prone transaction.
 	 *
 	 * This function invokes a callback function to perform a set of write
@@ -3318,7 +3204,8 @@ abstract class DatabaseBase implements IDatabase {
 	 * iteration, or false on error, for example if the retry limit was
 	 * reached.
 	 *
-	 * @return bool
+	 * @return mixed
+	 * @throws DBQueryError
 	 */
 	public function deadlockLoop() {
 		$args = func_get_args();
@@ -3332,15 +3219,13 @@ abstract class DatabaseBase implements IDatabase {
 
 		$this->begin( __METHOD__ );
 
+		$retVal = null;
 		$e = null;
 		do {
 			try {
 				$retVal = call_user_func_array( $function, $args );
 				break;
 			} catch ( DBQueryError $e ) {
-				$error = $this->lastError();
-				$errno = $this->lastErrno();
-				$sql = $this->lastQuery();
 				if ( $this->wasDeadlock() ) {
 					// Retry after a randomized delay
 					usleep( mt_rand( self::DEADLOCK_DELAY_MIN, self::DEADLOCK_DELAY_MAX ) );
@@ -3525,7 +3410,11 @@ abstract class DatabaseBase implements IDatabase {
 		if ( !$this->mTrxLevel ) {
 			$this->begin( $fname );
 			$this->mTrxAutomatic = true;
-			$this->mTrxAutomaticAtomic = true;
+			// If DBO_TRX is set, a series of startAtomic/endAtomic pairs will result
+			// in all changes being in one transaction to keep requests transactional.
+			if ( !$this->getFlag( DBO_TRX ) ) {
+				$this->mTrxAutomaticAtomic = true;
+			}
 		}
 
 		$this->mTrxAtomicLevels->push( $fname );
@@ -3605,19 +3494,18 @@ abstract class DatabaseBase implements IDatabase {
 			}
 
 			$this->runOnTransactionPreCommitCallbacks();
+			$writeTime = $this->pendingWriteQueryDuration();
 			$this->doCommit( $fname );
 			if ( $this->mTrxDoneWrites ) {
 				$this->mDoneWrites = microtime( true );
 				$this->getTransactionProfiler()->transactionWritingOut(
-					$this->mServer, $this->mDBname, $this->mTrxShortId );
+					$this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
 			}
 			$this->runOnTransactionIdleCallbacks();
 		}
 
 		# Avoid fatals if close() was called
-		if ( !$this->isOpen() ) {
-			throw new DBUnexpectedError( $this, "DB connection was already closed." );
-		}
+		$this->assertOpen();
 
 		$this->doBegin( $fname );
 		$this->mTrxTimestamp = microtime( true );
@@ -3629,6 +3517,7 @@ abstract class DatabaseBase implements IDatabase {
 		$this->mTrxIdleCallbacks = array();
 		$this->mTrxPreCommitCallbacks = array();
 		$this->mTrxShortId = wfRandomString( 12 );
+		$this->mTrxWriteDuration = 0.0;
 	}
 
 	/**
@@ -3681,16 +3570,15 @@ abstract class DatabaseBase implements IDatabase {
 		}
 
 		# Avoid fatals if close() was called
-		if ( !$this->isOpen() ) {
-			throw new DBUnexpectedError( $this, "DB connection was already closed." );
-		}
+		$this->assertOpen();
 
 		$this->runOnTransactionPreCommitCallbacks();
+		$writeTime = $this->pendingWriteQueryDuration();
 		$this->doCommit( $fname );
 		if ( $this->mTrxDoneWrites ) {
 			$this->mDoneWrites = microtime( true );
 			$this->getTransactionProfiler()->transactionWritingOut(
-				$this->mServer, $this->mDBname, $this->mTrxShortId );
+				$this->mServer, $this->mDBname, $this->mTrxShortId, $writeTime );
 		}
 		$this->runOnTransactionIdleCallbacks();
 	}
@@ -3739,9 +3627,7 @@ abstract class DatabaseBase implements IDatabase {
 		}
 
 		# Avoid fatals if close() was called
-		if ( !$this->isOpen() ) {
-			throw new DBUnexpectedError( $this, "DB connection was already closed." );
-		}
+		$this->assertOpen();
 
 		$this->doRollback( $fname );
 		$this->mTrxIdleCallbacks = array(); // cancel
@@ -3794,6 +3680,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string $prefix Only show tables with this prefix, e.g. mw_
 	 * @param string $fname Calling function name
 	 * @throws MWException
+	 * @return array
 	 */
 	function listTables( $prefix = null, $fname = __METHOD__ ) {
 		throw new MWException( 'DatabaseBase::listTables is not implemented in descendant class' );
@@ -3816,6 +3703,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @param string $prefix Only show VIEWs with this prefix, eg. unit_test_
 	 * @param string $fname Name of calling function
 	 * @throws MWException
+	 * @return array
 	 * @since 1.22
 	 */
 	public function listViews( $prefix = null, $fname = __METHOD__ ) {
@@ -3827,6 +3715,7 @@ abstract class DatabaseBase implements IDatabase {
 	 *
 	 * @param string $name Name of the database-structure to test.
 	 * @throws MWException
+	 * @return bool
 	 * @since 1.22
 	 */
 	public function isView( $name ) {
@@ -3988,9 +3877,9 @@ abstract class DatabaseBase implements IDatabase {
 	public function sourceFile(
 		$filename, $lineCallback = false, $resultCallback = false, $fname = false, $inputCallback = false
 	) {
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$fp = fopen( $filename, 'r' );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( false === $fp ) {
 			throw new MWException( "Could not open \"{$filename}\".\n" );
@@ -4205,7 +4094,7 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
-	 * Check to see if a named lock is available. This is non-blocking.
+	 * Check to see if a named lock is available (non-blocking)
 	 *
 	 * @param string $lockName Name of lock to poll
 	 * @param string $method Name of method calling us
@@ -4219,8 +4108,7 @@ abstract class DatabaseBase implements IDatabase {
 	/**
 	 * Acquire a named lock
 	 *
-	 * Abstracted from Filestore::lock() so child classes can implement for
-	 * their own needs.
+	 * Named locks are not related to transactions
 	 *
 	 * @param string $lockName Name of lock to aquire
 	 * @param string $method Name of method calling us
@@ -4232,7 +4120,9 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
-	 * Release a lock.
+	 * Release a lock
+	 *
+	 * Named locks are not related to transactions
 	 *
 	 * @param string $lockName Name of lock to release
 	 * @param string $method Name of method calling us
@@ -4246,6 +4136,16 @@ abstract class DatabaseBase implements IDatabase {
 	}
 
 	/**
+	 * Check to see if a named lock used by lock() use blocking queues
+	 *
+	 * @return bool
+	 * @since 1.26
+	 */
+	public function namedLocksEnqueue() {
+		return false;
+	}
+
+	/**
 	 * Lock specific tables
 	 *
 	 * @param array $read Array of tables to lock for read access
@@ -4328,7 +4228,7 @@ abstract class DatabaseBase implements IDatabase {
 	 * @return string
 	 */
 	public function decodeExpiry( $expiry, $format = TS_MW ) {
-		return ( $expiry == '' || $expiry == $this->getInfinity() )
+		return ( $expiry == '' || $expiry == 'infinity' || $expiry == $this->getInfinity() )
 			? 'infinity'
 			: wfTimestamp( $format, $expiry );
 	}
diff --git a/includes/db/DatabaseError.php b/includes/db/DatabaseError.php
index 86950a89..928de616 100644
--- a/includes/db/DatabaseError.php
+++ b/includes/db/DatabaseError.php
@@ -329,12 +329,19 @@ class DBQueryError extends DBExpectedError {
 	 * @param string $fname
 	 */
 	function __construct( DatabaseBase $db, $error, $errno, $sql, $fname ) {
-		$message = "A database error has occurred. Did you forget to run " .
-			"maintenance/update.php after upgrading?  See: " .
-			"https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
-			"Query: $sql\n" .
-			"Function: $fname\n" .
-			"Error: $errno $error\n";
+		if ( $db->wasConnectionError( $errno ) ) {
+			$message = "A connection error occured. \n" .
+				"Query: $sql\n" .
+				"Function: $fname\n" .
+				"Error: $errno $error\n";
+		} else {
+			$message = "A database error has occurred. Did you forget to run " .
+				"maintenance/update.php after upgrading?  See: " .
+				"https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script\n" .
+				"Query: $sql\n" .
+				"Function: $fname\n" .
+				"Error: $errno $error\n";
+		}
 		parent::__construct( $db, $message );
 
 		$this->error = $error;
diff --git a/includes/db/DatabaseMssql.php b/includes/db/DatabaseMssql.php
index 2b8f395f..85f1b96d 100644
--- a/includes/db/DatabaseMssql.php
+++ b/includes/db/DatabaseMssql.php
@@ -119,9 +119,9 @@ class DatabaseMssql extends DatabaseBase {
 			$connectionInfo['PWD'] = $password;
 		}
 
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$this->mConn = sqlsrv_connect( $server, $connectionInfo );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( $this->mConn === false ) {
 			throw new DBConnectionError( $this, $this->lastError() );
@@ -1089,7 +1089,9 @@ class DatabaseMssql extends DatabaseBase {
 	 * @param string $s
 	 * @return string
 	 */
-	public function strencode( $s ) { # Should not be called by us
+	public function strencode( $s ) {
+		// Should not be called by us
+
 		return str_replace( "'", "''", $s );
 	}
 
diff --git a/includes/db/DatabaseMysql.php b/includes/db/DatabaseMysql.php
index 823d9b67..5b151477 100644
--- a/includes/db/DatabaseMysql.php
+++ b/includes/db/DatabaseMysql.php
@@ -33,10 +33,12 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @return resource False on error
 	 */
 	protected function doQuery( $sql ) {
+		$conn = $this->getBindingHandle();
+
 		if ( $this->bufferResults() ) {
-			$ret = mysql_query( $sql, $this->mConn );
+			$ret = mysql_query( $sql, $conn );
 		} else {
-			$ret = mysql_unbuffered_query( $sql, $this->mConn );
+			$ret = mysql_unbuffered_query( $sql, $conn );
 		}
 
 		return $ret;
@@ -48,8 +50,7 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @throws DBConnectionError
 	 */
 	protected function mysqlConnect( $realServer ) {
-		# Fail now
-		# Otherwise we get a suppressed fatal error, which is very hard to track down
+		# Avoid a suppressed fatal error, which is very hard to track down
 		if ( !extension_loaded( 'mysql' ) ) {
 			throw new DBConnectionError(
 				$this,
@@ -73,6 +74,9 @@ class DatabaseMysql extends DatabaseMysqlBase {
 
 		$conn = false;
 
+		# The kernel's default SYN retransmission period is far too slow for us,
+		# so we use a short timeout plus a manual retry. Retrying means that a small
+		# but finite rate of SYN packet loss won't cause user-visible errors.
 		for ( $i = 0; $i < $numAttempts && !$conn; $i++ ) {
 			if ( $i > 1 ) {
 				usleep( 1000 );
@@ -93,8 +97,10 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	protected function mysqlSetCharset( $charset ) {
+		$conn = $this->getBindingHandle();
+
 		if ( function_exists( 'mysql_set_charset' ) ) {
-			return mysql_set_charset( $charset, $this->mConn );
+			return mysql_set_charset( $charset, $conn );
 		} else {
 			return $this->query( 'SET NAMES ' . $charset, __METHOD__ );
 		}
@@ -104,14 +110,18 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	protected function closeConnection() {
-		return mysql_close( $this->mConn );
+		$conn = $this->getBindingHandle();
+
+		return mysql_close( $conn );
 	}
 
 	/**
 	 * @return int
 	 */
 	function insertId() {
-		return mysql_insert_id( $this->mConn );
+		$conn = $this->getBindingHandle();
+
+		return mysql_insert_id( $conn );
 	}
 
 	/**
@@ -129,7 +139,9 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @return int
 	 */
 	function affectedRows() {
-		return mysql_affected_rows( $this->mConn );
+		$conn = $this->getBindingHandle();
+
+		return mysql_affected_rows( $conn );
 	}
 
 	/**
@@ -137,9 +149,11 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	function selectDB( $db ) {
+		$conn = $this->getBindingHandle();
+
 		$this->mDBname = $db;
 
-		return mysql_select_db( $db, $this->mConn );
+		return mysql_select_db( $db, $conn );
 	}
 
 	protected function mysqlFreeResult( $res ) {
@@ -183,10 +197,14 @@ class DatabaseMysql extends DatabaseMysqlBase {
 	}
 
 	protected function mysqlRealEscapeString( $s ) {
-		return mysql_real_escape_string( $s, $this->mConn );
+		$conn = $this->getBindingHandle();
+
+		return mysql_real_escape_string( $s, $conn );
 	}
 
 	protected function mysqlPing() {
-		return mysql_ping( $this->mConn );
+		$conn = $this->getBindingHandle();
+
+		return mysql_ping( $conn );
 	}
 }
diff --git a/includes/db/DatabaseMysqlBase.php b/includes/db/DatabaseMysqlBase.php
index aac95a8c..be34242b 100644
--- a/includes/db/DatabaseMysqlBase.php
+++ b/includes/db/DatabaseMysqlBase.php
@@ -59,22 +59,16 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 	function open( $server, $user, $password, $dbName ) {
 		global $wgAllDBsAreLocalhost, $wgSQLMode;
 
-		# Debugging hack -- fake cluster
-		if ( $wgAllDBsAreLocalhost ) {
-			$realServer = 'localhost';
-		} else {
-			$realServer = $server;
-		}
+		# Close/unset connection handle
 		$this->close();
+
+		# Debugging hack -- fake cluster
+		$realServer = $wgAllDBsAreLocalhost ? 'localhost' : $server;
 		$this->mServer = $server;
 		$this->mUser = $user;
 		$this->mPassword = $password;
 		$this->mDBname = $dbName;
 
-		# The kernel's default SYN retransmission period is far too slow for us,
-		# so we use a short timeout plus a manual retry. Retrying means that a small
-		# but finite rate of SYN packet loss won't cause user-visible errors.
-		$this->mConn = false;
 		$this->installErrorHandler();
 		try {
 			$this->mConn = $this->mysqlConnect( $realServer );
@@ -104,9 +98,9 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		}
 
 		if ( $dbName != '' ) {
-			wfSuppressWarnings();
+			MediaWiki\suppressWarnings();
 			$success = $this->selectDB( $dbName );
-			wfRestoreWarnings();
+			MediaWiki\restoreWarnings();
 			if ( !$success ) {
 				wfLogDBError(
 					"Error selecting database {db_name} on server {db_server}",
@@ -132,6 +126,15 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		if ( is_string( $wgSQLMode ) ) {
 			$set[] = 'sql_mode = ' . $this->addQuotes( $wgSQLMode );
 		}
+		// Set any custom settings defined by site config
+		// (e.g. https://dev.mysql.com/doc/refman/4.1/en/innodb-parameters.html)
+		foreach ( $this->mSessionVars as $var => $val ) {
+			// Escape strings but not numbers to avoid MySQL complaining
+			if ( !is_int( $val ) && !is_float( $val ) ) {
+				$val = $this->addQuotes( $val );
+			}
+			$set[] = $this->addIdentifierQuotes( $var ) . ' = ' . $val;
+		}
 
 		if ( $set ) {
 			// Use doQuery() to avoid opening implicit transactions (DBO_TRX)
@@ -194,9 +197,9 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$ok = $this->mysqlFreeResult( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		if ( !$ok ) {
 			throw new DBUnexpectedError( $this, "Unable to free MySQL result" );
 		}
@@ -219,9 +222,9 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$row = $this->mysqlFetchObject( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		$errno = $this->lastErrno();
 		// Unfortunately, mysql_fetch_object does not reset the last errno.
@@ -255,9 +258,9 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$row = $this->mysqlFetchArray( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		$errno = $this->lastErrno();
 		// Unfortunately, mysql_fetch_array does not reset the last errno.
@@ -291,9 +294,9 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$n = $this->mysqlNumRows( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		// Unfortunately, mysql_num_rows does not reset the last errno.
 		// We are not checking for any errors here, since
@@ -404,12 +407,12 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 	function lastError() {
 		if ( $this->mConn ) {
 			# Even if it's non-zero, it can still be invalid
-			wfSuppressWarnings();
+			MediaWiki\suppressWarnings();
 			$error = $this->mysqlError( $this->mConn );
 			if ( !$error ) {
 				$error = $this->mysqlError();
 			}
-			wfRestoreWarnings();
+			MediaWiki\restoreWarnings();
 		} else {
 			$error = $this->mysqlError();
 		}
@@ -577,9 +580,12 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 	function ping() {
 		$ping = $this->mysqlPing();
 		if ( $ping ) {
+			// Connection was good or lost but reconnected...
+			// @note: mysqlnd (php 5.6+) does not support this (PHP bug 52561)
 			return true;
 		}
 
+		// Try a full disconnect/reconnect cycle if ping() failed
 		$this->closeConnection();
 		$this->mOpened = false;
 		$this->mConn = false;
@@ -873,6 +879,10 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 		return ( $row->lockstatus == 1 );
 	}
 
+	public function namedLocksEnqueue() {
+		return true;
+	}
+
 	/**
 	 * @param array $read
 	 * @param array $write
@@ -930,7 +940,7 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 				$value = $this->mDefaultBigSelects;
 			}
 		} elseif ( $this->mDefaultBigSelects === null ) {
-			$this->mDefaultBigSelects = (bool)$this->selectField( false, '@@sql_big_selects' );
+			$this->mDefaultBigSelects = (bool)$this->selectField( false, '@@sql_big_selects', '', __METHOD__ );
 		}
 		$encValue = $value ? '1' : '0';
 		$this->query( "SET sql_big_selects=$encValue", __METHOD__ );
@@ -1045,6 +1055,32 @@ abstract class DatabaseMysqlBase extends DatabaseBase {
 			( $this->lastErrno() == 1290 && strpos( $this->lastError(), '--read-only' ) !== false );
 	}
 
+	function wasConnectionError( $errno ) {
+		return $errno == 2013 || $errno == 2006;
+	}
+
+	/**
+	 * Get the underlying binding handle, mConn
+	 *
+	 * Makes sure that mConn is set (disconnects and ping() failure can unset it).
+	 * This catches broken callers than catch and ignore disconnection exceptions.
+	 * Unlike checking isOpen(), this is safe to call inside of open().
+	 *
+	 * @return resource|object
+	 * @throws DBUnexpectedError
+	 * @since 1.26
+	 */
+	protected function getBindingHandle() {
+		if ( !$this->mConn ) {
+			throw new DBUnexpectedError(
+				$this,
+				'DB connection was already closed or the connection dropped.'
+			);
+		}
+
+		return $this->mConn;
+	}
+
 	/**
 	 * @param string $oldName
 	 * @param string $newName
diff --git a/includes/db/DatabaseMysqli.php b/includes/db/DatabaseMysqli.php
index ad12e196..8ca23627 100644
--- a/includes/db/DatabaseMysqli.php
+++ b/includes/db/DatabaseMysqli.php
@@ -29,15 +29,20 @@
  * @see Database
  */
 class DatabaseMysqli extends DatabaseMysqlBase {
+	/** @var mysqli */
+	protected $mConn;
+
 	/**
 	 * @param string $sql
 	 * @return resource
 	 */
 	protected function doQuery( $sql ) {
+		$conn = $this->getBindingHandle();
+
 		if ( $this->bufferResults() ) {
-			$ret = $this->mConn->query( $sql );
+			$ret = $conn->query( $sql );
 		} else {
-			$ret = $this->mConn->query( $sql, MYSQLI_USE_RESULT );
+			$ret = $conn->query( $sql, MYSQLI_USE_RESULT );
 		}
 
 		return $ret;
@@ -50,8 +55,8 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 */
 	protected function mysqlConnect( $realServer ) {
 		global $wgDBmysql5;
-		# Fail now
-		# Otherwise we get a suppressed fatal error, which is very hard to track down
+
+		# Avoid suppressed fatal error, which is very hard to track down
 		if ( !function_exists( 'mysqli_init' ) ) {
 			throw new DBConnectionError( $this, "MySQLi functions missing,"
 				. " have you compiled PHP with the --with-mysqli option?\n" );
@@ -116,8 +121,10 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	protected function mysqlSetCharset( $charset ) {
-		if ( method_exists( $this->mConn, 'set_charset' ) ) {
-			return $this->mConn->set_charset( $charset );
+		$conn = $this->getBindingHandle();
+
+		if ( method_exists( $conn, 'set_charset' ) ) {
+			return $conn->set_charset( $charset );
 		} else {
 			return $this->query( 'SET NAMES ' . $charset, __METHOD__ );
 		}
@@ -127,14 +134,18 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	protected function closeConnection() {
-		return $this->mConn->close();
+		$conn = $this->getBindingHandle();
+
+		return $conn->close();
 	}
 
 	/**
 	 * @return int
 	 */
 	function insertId() {
-		return $this->mConn->insert_id;
+		$conn = $this->getBindingHandle();
+
+		return (int)$conn->insert_id;
 	}
 
 	/**
@@ -152,7 +163,9 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 * @return int
 	 */
 	function affectedRows() {
-		return $this->mConn->affected_rows;
+		$conn = $this->getBindingHandle();
+
+		return $conn->affected_rows;
 	}
 
 	/**
@@ -160,9 +173,11 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 * @return bool
 	 */
 	function selectDB( $db ) {
+		$conn = $this->getBindingHandle();
+
 		$this->mDBname = $db;
 
-		return $this->mConn->select_db( $db );
+		return $conn->select_db( $db );
 	}
 
 	/**
@@ -289,11 +304,15 @@ class DatabaseMysqli extends DatabaseMysqlBase {
 	 * @return string
 	 */
 	protected function mysqlRealEscapeString( $s ) {
-		return $this->mConn->real_escape_string( $s );
+		$conn = $this->getBindingHandle();
+
+		return $conn->real_escape_string( $s );
 	}
 
 	protected function mysqlPing() {
-		return $this->mConn->ping();
+		$conn = $this->getBindingHandle();
+
+		return $conn->ping();
 	}
 
 	/**
diff --git a/includes/db/DatabaseOracle.php b/includes/db/DatabaseOracle.php
index 9b00fbd1..87c31646 100644
--- a/includes/db/DatabaseOracle.php
+++ b/includes/db/DatabaseOracle.php
@@ -220,9 +220,9 @@ class DatabaseOracle extends DatabaseBase {
 
 	function __destruct() {
 		if ( $this->mOpened ) {
-			wfSuppressWarnings();
+			MediaWiki\suppressWarnings();
 			$this->close();
-			wfRestoreWarnings();
+			MediaWiki\restoreWarnings();
 		}
 	}
 
@@ -306,7 +306,7 @@ class DatabaseOracle extends DatabaseBase {
 
 		$session_mode = $this->mFlags & DBO_SYSDBA ? OCI_SYSDBA : OCI_DEFAULT;
 
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		if ( $this->mFlags & DBO_PERSISTENT ) {
 			$this->mConn = oci_pconnect(
 				$this->mUser,
@@ -332,7 +332,7 @@ class DatabaseOracle extends DatabaseBase {
 				$session_mode
 			);
 		}
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( $this->mUser != $this->mDBname ) {
 			//change current schema in session
@@ -393,7 +393,7 @@ class DatabaseOracle extends DatabaseBase {
 			$explain_count
 		);
 
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 
 		if ( ( $this->mLastResult = $stmt = oci_parse( $this->mConn, $sql ) ) === false ) {
 			$e = oci_error( $this->mConn );
@@ -411,7 +411,7 @@ class DatabaseOracle extends DatabaseBase {
 			}
 		}
 
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( $explain_count > 0 ) {
 			return $this->doQuery( 'SELECT id, cardinality "ROWS" FROM plan_table ' .
@@ -687,7 +687,7 @@ class DatabaseOracle extends DatabaseBase {
 			}
 		}
 
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 
 		if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
 			$e = oci_error( $stmt );
@@ -702,7 +702,7 @@ class DatabaseOracle extends DatabaseBase {
 			$this->mAffectedRows = oci_num_rows( $stmt );
 		}
 
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( isset( $lob ) ) {
 			foreach ( $lob as $lob_v ) {
@@ -971,20 +971,6 @@ class DatabaseOracle extends DatabaseBase {
 		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
 	 */
@@ -1250,9 +1236,9 @@ class DatabaseOracle extends DatabaseBase {
 		}
 		$sql = 'ALTER SESSION SET CURRENT_SCHEMA=' . strtoupper( $db );
 		$stmt = oci_parse( $this->mConn, $sql );
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$success = oci_execute( $stmt );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		if ( !$success ) {
 			$e = oci_error( $stmt );
 			if ( $e['code'] != '1435' ) {
@@ -1491,7 +1477,7 @@ class DatabaseOracle extends DatabaseBase {
 			}
 		}
 
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 
 		if ( oci_execute( $stmt, $this->execFlags() ) === false ) {
 			$e = oci_error( $stmt );
@@ -1506,7 +1492,7 @@ class DatabaseOracle extends DatabaseBase {
 			$this->mAffectedRows = oci_num_rows( $stmt );
 		}
 
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 
 		if ( isset( $lob ) ) {
 			foreach ( $lob as $lob_v ) {
diff --git a/includes/db/DatabasePostgres.php b/includes/db/DatabasePostgres.php
index 9287f7a6..56a5b2cf 100644
--- a/includes/db/DatabasePostgres.php
+++ b/includes/db/DatabasePostgres.php
@@ -217,7 +217,7 @@ class PostgresTransactionState {
  * @since 1.19
  */
 class SavepointPostgres {
-	/** @var DatabaseBase Establish a savepoint within a transaction */
+	/** @var DatabasePostgres Establish a savepoint within a transaction */
 	protected $dbw;
 	protected $id;
 	protected $didbegin;
@@ -551,9 +551,9 @@ class DatabasePostgres extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$ok = pg_free_result( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		if ( !$ok ) {
 			throw new DBUnexpectedError( $this, "Unable to free Postgres result\n" );
 		}
@@ -568,9 +568,9 @@ class DatabasePostgres extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$row = pg_fetch_object( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		# @todo FIXME: HACK HACK HACK HACK debug
 
 		# @todo hashar: not sure if the following test really trigger if the object
@@ -589,9 +589,9 @@ class DatabasePostgres extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$row = pg_fetch_array( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		if ( pg_last_error( $this->mConn ) ) {
 			throw new DBUnexpectedError(
 				$this,
@@ -606,9 +606,9 @@ class DatabasePostgres extends DatabaseBase {
 		if ( $res instanceof ResultWrapper ) {
 			$res = $res->result;
 		}
-		wfSuppressWarnings();
+		MediaWiki\suppressWarnings();
 		$n = pg_num_rows( $res );
-		wfRestoreWarnings();
+		MediaWiki\restoreWarnings();
 		if ( pg_last_error( $this->mConn ) ) {
 			throw new DBUnexpectedError(
 				$this,
@@ -1510,7 +1510,9 @@ SQL;
 		return pg_unescape_bytea( $b );
 	}
 
-	function strencode( $s ) { # Should not be called by us
+	function strencode( $s ) {
+		// Should not be called by us
+
 		return pg_escape_string( $this->mConn, $s );
 	}
 
@@ -1702,4 +1704,5 @@ SQL;
 	}
 } // end DatabasePostgres class
 
-class PostgresBlob extends Blob {}
+class PostgresBlob extends Blob {
+}
diff --git a/includes/db/DatabaseSqlite.php b/includes/db/DatabaseSqlite.php
index ed86bab1..656547b5 100644
--- a/includes/db/DatabaseSqlite.php
+++ b/includes/db/DatabaseSqlite.php
@@ -64,16 +64,16 @@ class DatabaseSqlite extends DatabaseBase {
 		$this->dbDir = isset( $p['dbDirectory'] ) ? $p['dbDirectory'] : $wgSQLiteDataDir;
 
 		if ( isset( $p['dbFilePath'] ) ) {
-			$this->mFlags = isset( $p['flags'] ) ? $p['flags'] : 0;
-			// Standalone .sqlite file mode
+			parent::__construct( $p );
+			// Standalone .sqlite file mode.
+			// Super doesn't open when $user is false, but we can work with $dbName,
+			// which is derived from the file path in this case.
 			$this->openFile( $p['dbFilePath'] );
-			// @FIXME: clean up base constructor so this can call super instead
-			$this->mTrxAtomicLevels = new SplStack;
 		} else {
 			$this->mDBname = $p['dbname'];
-			// Stock wiki mode using standard file names per DB
+			// Stock wiki mode using standard file names per DB.
 			parent::__construct( $p );
-			// parent doesn't open when $user is false, but we can work with $dbName
+			// Super doesn't open when $user is false, but we can work with $dbName
 			if ( $p['dbname'] && !$this->isOpen() ) {
 				if ( $this->open( $p['host'], $p['user'], $p['password'], $p['dbname'] ) ) {
 					if ( $wgSharedDB ) {
@@ -105,8 +105,10 @@ class DatabaseSqlite extends DatabaseBase {
 	 */
 	public static function newStandaloneInstance( $filename, array $p = array() ) {
 		$p['dbFilePath'] = $filename;
+		$p['schema'] = false;
+		$p['tablePrefix'] = '';
 
-		return new self( $p );
+		return DatabaseBase::factory( 'sqlite', $p );
 	}
 
 	/**
@@ -282,7 +284,7 @@ class DatabaseSqlite extends DatabaseBase {
 	 * @return bool
 	 */
 	function isWriteQuery( $sql ) {
-		return parent::isWriteQuery( $sql ) && !preg_match( '/^ATTACH\b/i', $sql );
+		return parent::isWriteQuery( $sql ) && !preg_match( '/^(ATTACH|PRAGMA)\b/i', $sql );
 	}
 
 	/**
@@ -962,7 +964,36 @@ class DatabaseSqlite extends DatabaseBase {
 			}
 		}
 
-		return $this->query( $sql, $fname );
+		$res = $this->query( $sql, $fname );
+
+		// Take over indexes
+		$indexList = $this->query( 'PRAGMA INDEX_LIST(' . $this->addQuotes( $oldName ) . ')' );
+		foreach ( $indexList as $index ) {
+			if ( strpos( $index->name, 'sqlite_autoindex' ) === 0 ) {
+				continue;
+			}
+
+			if ( $index->unique ) {
+				$sql = 'CREATE UNIQUE INDEX';
+			} else {
+				$sql = 'CREATE INDEX';
+			}
+			// Try to come up with a new index name, given indexes have database scope in SQLite
+			$indexName = $newName . '_' . $index->name;
+			$sql .= ' ' . $indexName . ' ON ' . $newName;
+
+			$indexInfo = $this->query( 'PRAGMA INDEX_INFO(' . $this->addQuotes( $index->name ) . ')' );
+			$fields = array();
+			foreach ( $indexInfo as $indexInfoRow ) {
+				$fields[ $indexInfoRow->seqno ] = $indexInfoRow->name;
+			}
+
+			$sql .= '(' . implode( ',', $fields ) . ')';
+
+			$this->query( $sql );
+		}
+
+		return $res;
 	}
 
 	/**
diff --git a/includes/db/IDatabase.php b/includes/db/IDatabase.php
new file mode 100644
index 00000000..49d0514d
--- /dev/null
+++ b/includes/db/IDatabase.php
@@ -0,0 +1,1513 @@
+<?php
+
+/**
+ * @defgroup Database Database
+ *
+ * This file deals with database interface functions
+ * and query specifics/optimisations.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+
+/**
+ * Basic database interface for live and lazy-loaded DB handles
+ *
+ * @todo: loosen up DB classes from MWException
+ * @note: DatabaseBase and DBConnRef should be updated to reflect any changes
+ * @ingroup Database
+ */
+interface IDatabase {
+	/**
+	 * 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();
+
+	/**
+	 * 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 null|bool $buffer
+	 * @return null|bool The previous value of the flag
+	 */
+	public function bufferResults( $buffer = null );
+
+	/**
+	 * Gets the current transaction level.
+	 *
+	 * Historically, transactions were allowed to be "nested". This is no
+	 * longer supported, so this function really only returns a boolean.
+	 *
+	 * @return int The previous value
+	 */
+	public function trxLevel();
+
+	/**
+	 * Get the UNIX timestamp of the time that the transaction was established
+	 *
+	 * This can be used to reason about the staleness of SELECT data
+	 * in REPEATABLE-READ transaction isolation level.
+	 *
+	 * @return float|null Returns null if there is not active transaction
+	 * @since 1.25
+	 */
+	public function trxTimestamp();
+
+	/**
+	 * Get/set the table prefix.
+	 * @param string $prefix The table prefix to set, or omitted to leave it unchanged.
+	 * @return string The previous table prefix.
+	 */
+	public function tablePrefix( $prefix = null );
+
+	/**
+	 * Get/set the db schema.
+	 * @param string $schema The database schema to set, or omitted to leave it unchanged.
+	 * @return string The previous db schema.
+	 */
+	public function dbSchema( $schema = null );
+
+	/**
+	 * Get properties passed down from the server info array of the load
+	 * balancer.
+	 *
+	 * @param string $name The entry of the info array to get, or null to get the
+	 *   whole array
+	 *
+	 * @return array|mixed|null
+	 */
+	public function getLBInfo( $name = 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 string $name
+	 * @param array $value
+	 */
+	public function setLBInfo( $name, $value = null );
+
+	/**
+	 * Returns true if this database does an implicit sort when doing GROUP BY
+	 *
+	 * @return bool
+	 */
+	public function implicitGroupby();
+
+	/**
+	 * 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
+	 */
+	public function implicitOrderby();
+
+	/**
+	 * Return the last query that went through DatabaseBase::query()
+	 * @return string
+	 */
+	public function lastQuery();
+
+	/**
+	 * Returns true if the connection may have been used for write queries.
+	 * Should return true if unsure.
+	 *
+	 * @return bool
+	 */
+	public function doneWrites();
+
+	/**
+	 * Returns the last time the connection may have been used for write queries.
+	 * Should return a timestamp if unsure.
+	 *
+	 * @return int|float UNIX timestamp or false
+	 * @since 1.24
+	 */
+	public function lastDoneWrites();
+
+	/**
+	 * Returns true if there is a transaction open with possible write
+	 * queries or transaction pre-commit/idle callbacks waiting on it to finish.
+	 *
+	 * @return bool
+	 */
+	public function writesOrCallbacksPending();
+
+	/**
+	 * Get the time spend running write queries for this
+	 *
+	 * High times could be due to scanning, updates, locking, and such
+	 *
+	 * @return float|bool Returns false if not transaction is active
+	 * @since 1.26
+	 */
+	public function pendingWriteQueryDuration();
+
+	/**
+	 * Is a connection to the database open?
+	 * @return bool
+	 */
+	public function isOpen();
+
+	/**
+	 * Set a flag for this connection
+	 *
+	 * @param int $flag DBO_* constants from Defines.php:
+	 *   - DBO_DEBUG: output some debug info (same as debug())
+	 *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
+	 *   - 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
+	 */
+	public function setFlag( $flag );
+
+	/**
+	 * Clear a flag for this connection
+	 *
+	 * @param int $flag DBO_* constants from Defines.php:
+	 *   - DBO_DEBUG: output some debug info (same as debug())
+	 *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
+	 *   - 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
+	 */
+	public function clearFlag( $flag );
+
+	/**
+	 * Returns a boolean whether the flag $flag is set for this connection
+	 *
+	 * @param int $flag DBO_* constants from Defines.php:
+	 *   - DBO_DEBUG: output some debug info (same as debug())
+	 *   - DBO_NOBUFFER: don't buffer results (inverse of bufferResults())
+	 *   - DBO_TRX: automatically start transactions
+	 *   - DBO_PERSISTENT: use persistant database connection
+	 * @return bool
+	 */
+	public function getFlag( $flag );
+
+	/**
+	 * General read-only accessor
+	 *
+	 * @param string $name
+	 * @return string
+	 */
+	public function getProperty( $name );
+
+	/**
+	 * @return string
+	 */
+	public function getWikiID();
+
+	/**
+	 * Get the type of the DBMS, as it appears in $wgDBtype.
+	 *
+	 * @return string
+	 */
+	public function getType();
+
+	/**
+	 * Open a connection to the database. Usually aborts on failure
+	 *
+	 * @param string $server Database server host
+	 * @param string $user Database user name
+	 * @param string $password Database user password
+	 * @param string $dbName Database name
+	 * @return bool
+	 * @throws DBConnectionError
+	 */
+	public 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.
+	 * If no more rows are available, false is returned.
+	 *
+	 * @param ResultWrapper|stdClass $res Object as returned from DatabaseBase::query(), etc.
+	 * @return stdClass|bool
+	 * @throws DBUnexpectedError Thrown if the database returns an error
+	 */
+	public function fetchObject( $res );
+
+	/**
+	 * Fetch the next row from the given result object, in associative array
+	 * form. Fields are retrieved with $row['fieldname'].
+	 * If no more rows are available, false is returned.
+	 *
+	 * @param ResultWrapper $res Result object as returned from DatabaseBase::query(), etc.
+	 * @return array|bool
+	 * @throws DBUnexpectedError Thrown if the database returns an error
+	 */
+	public function fetchRow( $res );
+
+	/**
+	 * Get the number of rows in a result object
+	 *
+	 * @param mixed $res A SQL result
+	 * @return int
+	 */
+	public function numRows( $res );
+
+	/**
+	 * Get the number of fields in a result object
+	 * @see http://www.php.net/mysql_num_fields
+	 *
+	 * @param mixed $res A SQL result
+	 * @return int
+	 */
+	public function numFields( $res );
+
+	/**
+	 * Get a field name in a result object
+	 * @see http://www.php.net/mysql_field_name
+	 *
+	 * @param mixed $res A SQL result
+	 * @param int $n
+	 * @return string
+	 */
+	public 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
+	 */
+	public function insertId();
+
+	/**
+	 * Change the position of the cursor in a result object
+	 * @see http://www.php.net/mysql_data_seek
+	 *
+	 * @param mixed $res A SQL result
+	 * @param int $row
+	 */
+	public function dataSeek( $res, $row );
+
+	/**
+	 * Get the last error number
+	 * @see http://www.php.net/mysql_errno
+	 *
+	 * @return int
+	 */
+	public function lastErrno();
+
+	/**
+	 * Get a description of the last error
+	 * @see http://www.php.net/mysql_error
+	 *
+	 * @return string
+	 */
+	public function lastError();
+
+	/**
+	 * mysql_fetch_field() wrapper
+	 * Returns false if the field doesn't exist
+	 *
+	 * @param string $table Table name
+	 * @param string $field Field name
+	 *
+	 * @return Field
+	 */
+	public function fieldInfo( $table, $field );
+
+	/**
+	 * Get the number of rows affected by the last write query
+	 * @see http://www.php.net/mysql_affected_rows
+	 *
+	 * @return int
+	 */
+	public function affectedRows();
+
+	/**
+	 * 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
+	 */
+	public function getSoftwareLink();
+
+	/**
+	 * A string describing the current software version, like from
+	 * mysql_get_server_info().
+	 *
+	 * @return string Version information from the database server.
+	 */
+	public function getServerVersion();
+
+	/**
+	 * Closes a database connection.
+	 * if it is open : commits any open transactions
+	 *
+	 * @throws MWException
+	 * @return bool Operation success. true if already closed.
+	 */
+	public function close();
+
+	/**
+	 * @param string $error Fallback error message, used if none is given by DB
+	 * @throws DBConnectionError
+	 */
+	public function reportConnectionError( $error = 'Unknown error' );
+
+	/**
+	 * 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 string $sql SQL query
+	 * @param string $fname Name of the calling function, for profiling/SHOW PROCESSLIST
+	 *     comment (you can use __METHOD__ or add some extra info)
+	 * @param bool $tempIgnore Whether to avoid throwing an exception on errors...
+	 *     maybe best to catch the exception instead?
+	 * @throws MWException
+	 * @return bool|ResultWrapper True for a successful write query, ResultWrapper object
+	 *     for a successful read query, or false on failure if $tempIgnore set
+	 */
+	public function query( $sql, $fname = __METHOD__, $tempIgnore = false );
+
+	/**
+	 * Report a query error. Log the error, and if neither the object ignore
+	 * flag nor the $tempIgnore flag is set, throw a DBQueryError.
+	 *
+	 * @param string $error
+	 * @param int $errno
+	 * @param string $sql
+	 * @param string $fname
+	 * @param bool $tempIgnore
+	 * @throws DBQueryError
+	 */
+	public function reportQueryError( $error, $errno, $sql, $fname, $tempIgnore = false );
+
+	/**
+	 * 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 mixed $res A SQL result
+	 */
+	public function freeResult( $res );
+
+	/**
+	 * 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 string|array $table Table name. See DatabaseBase::select() for details.
+	 * @param string $var The field name to select. This must be a valid SQL
+	 *   fragment: do not use unvalidated user input.
+	 * @param string|array $cond The condition array. See DatabaseBase::select() for details.
+	 * @param string $fname The function name of the caller.
+	 * @param string|array $options The query options. See DatabaseBase::select() for details.
+	 *
+	 * @return bool|mixed The value from the field, or false on failure.
+	 */
+	public function selectField(
+		$table, $var, $cond = '', $fname = __METHOD__, $options = array()
+	);
+
+	/**
+	 * A SELECT wrapper which returns a list of single field values from result rows.
+	 *
+	 * 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 string|array $table Table name. See DatabaseBase::select() for details.
+	 * @param string $var The field name to select. This must be a valid SQL
+	 *   fragment: do not use unvalidated user input.
+	 * @param string|array $cond The condition array. See DatabaseBase::select() for details.
+	 * @param string $fname The function name of the caller.
+	 * @param string|array $options The query options. See DatabaseBase::select() for details.
+	 *
+	 * @return bool|array The values from the field, or false on failure
+	 * @since 1.25
+	 */
+	public function selectFieldValues(
+		$table, $var, $cond = '', $fname = __METHOD__, $options = array()
+	);
+
+	/**
+	 * Execute a SELECT query constructed using the various parameters provided.
+	 * See below for full details of the parameters.
+	 *
+	 * @param string|array $table Table name
+	 * @param string|array $vars Field names
+	 * @param string|array $conds Conditions
+	 * @param string $fname Caller function name
+	 * @param array $options Query options
+	 * @param array $join_conds Join conditions
+	 *
+	 *
+	 * @param string|array $table
+	 *
+	 * 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 string|array $vars
+	 *
+	 * May be either a field name or an array of field names. The field names
+	 * can be complete fragments of SQL, for direct inclusion into the SELECT
+	 * query. If an array is given, field aliases can be specified, for example:
+	 *
+	 *   array( 'maxrev' => 'MAX(rev_id)' )
+	 *
+	 * This includes an expression with the alias "maxrev" in the query.
+	 *
+	 * If an expression is given, care must be taken to ensure that it is
+	 * DBMS-independent.
+	 *
+	 *
+	 * @param string|array $conds
+	 *
+	 * 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
+	 *       from its non-null elements, and an IS NULL clause will be added
+	 *       if null is present, such that the field may match any of the
+	 *       elements in the array. The non-null elements 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 string|array $options
+	 *
+	 * 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: May be either an string containing a HAVING clause or an array of
+	 *     conditions building the HAVING clause. If an array is given, the conditions
+	 *     constructed from each element are combined with AND.
+	 *
+	 *   - 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 string|array $join_conds
+	 *
+	 * 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|bool 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.
+	 */
+	public function select(
+		$table, $vars, $conds = '', $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	);
+
+	/**
+	 * The equivalent of DatabaseBase::select() except that the constructed SQL
+	 * is returned, instead of being immediately executed. This can be useful for
+	 * doing UNION queries, where the SQL text of each query is needed. In general,
+	 * however, callers outside of Database classes should just use select().
+	 *
+	 * @param string|array $table Table name
+	 * @param string|array $vars Field names
+	 * @param string|array $conds Conditions
+	 * @param string $fname Caller function name
+	 * @param string|array $options Query options
+	 * @param string|array $join_conds Join conditions
+	 *
+	 * @return string SQL query string.
+	 * @see DatabaseBase::select()
+	 */
+	public function selectSQLText(
+		$table, $vars, $conds = '', $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	);
+
+	/**
+	 * 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 string|array $table Table name
+	 * @param string|array $vars Field names
+	 * @param array $conds Conditions
+	 * @param string $fname Caller function name
+	 * @param string|array $options Query options
+	 * @param array|string $join_conds Join conditions
+	 *
+	 * @return stdClass|bool
+	 */
+	public function selectRow( $table, $vars, $conds, $fname = __METHOD__,
+		$options = array(), $join_conds = array()
+	);
+
+	/**
+	 * Estimate the number of 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 string $table Table name
+	 * @param string $vars Unused
+	 * @param array|string $conds Filters on the table
+	 * @param string $fname Function name for profiling
+	 * @param array $options Options for select
+	 * @return int Row count
+	 */
+	public function estimateRowCount(
+		$table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
+	);
+
+	/**
+	 * Get the number of rows in dataset
+	 *
+	 * This is useful when trying to do COUNT(*) but with a LIMIT for performance.
+	 *
+	 * Takes the same arguments as DatabaseBase::select().
+	 *
+	 * @param string $table Table name
+	 * @param string $vars Unused
+	 * @param array|string $conds Filters on the table
+	 * @param string $fname Function name for profiling
+	 * @param array $options Options for select
+	 * @return int Row count
+	 * @since 1.24
+	 */
+	public function selectRowCount(
+		$table, $vars = '*', $conds = '', $fname = __METHOD__, $options = array()
+	);
+
+	/**
+	 * Determines whether a field exists in a table
+	 *
+	 * @param string $table Table name
+	 * @param string $field Filed to check on that table
+	 * @param string $fname Calling function name (optional)
+	 * @return bool Whether $table has filed $field
+	 */
+	public function fieldExists( $table, $field, $fname = __METHOD__ );
+
+	/**
+	 * Determines whether an index exists
+	 * Usually throws a DBQueryError on failure
+	 * If errors are explicitly ignored, returns NULL on failure
+	 *
+	 * @param string $table
+	 * @param string $index
+	 * @param string $fname
+	 * @return bool|null
+	 */
+	public function indexExists( $table, $index, $fname = __METHOD__ );
+
+	/**
+	 * Query whether a given table exists
+	 *
+	 * @param string $table
+	 * @param string $fname
+	 * @return bool
+	 */
+	public function tableExists( $table, $fname = __METHOD__ );
+
+	/**
+	 * Determines if a given index is unique
+	 *
+	 * @param string $table
+	 * @param string $index
+	 *
+	 * @return bool
+	 */
+	public function indexUnique( $table, $index );
+
+	/**
+	 * 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 string $table Table name. This will be passed through
+	 *   DatabaseBase::tableName().
+	 * @param array $a Array of rows to insert
+	 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
+	 * @param array $options Array of options
+	 *
+	 * @return bool
+	 */
+	public function insert( $table, $a, $fname = __METHOD__, $options = array() );
+
+	/**
+	 * UPDATE wrapper. Takes a condition array and a SET array.
+	 *
+	 * @param string $table Name of the table to UPDATE. This will be passed through
+	 *   DatabaseBase::tableName().
+	 * @param array $values 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 array $conds An array of conditions (WHERE). See
+	 *   DatabaseBase::select() for the details of the format of condition
+	 *   arrays. Use '*' to update all rows.
+	 * @param string $fname The function name of the caller (from __METHOD__),
+	 *   for logging and profiling.
+	 * @param array $options An array of UPDATE options, can be:
+	 *   - IGNORE: Ignore unique key conflicts
+	 *   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
+	 * @return bool
+	 */
+	public function update( $table, $values, $conds, $fname = __METHOD__, $options = array() );
+
+	/**
+	 * Makes an encoded list of strings from an array
+	 *
+	 * @param array $a Containing the data
+	 * @param int $mode Constant
+	 *    - LIST_COMMA: Comma separated, no field names
+	 *    - LIST_AND:   ANDed WHERE clause (without the WHERE). See the
+	 *      documentation for $conds in DatabaseBase::select().
+	 *    - LIST_OR:    ORed WHERE clause (without the WHERE)
+	 *    - LIST_SET:   Comma separated with field names, like a SET clause
+	 *    - LIST_NAMES: Comma separated field names
+	 * @throws MWException|DBUnexpectedError
+	 * @return string
+	 */
+	public function makeList( $a, $mode = LIST_COMMA );
+
+	/**
+	 * Build a partial where clause from a 2-d array such as used for LinkBatch.
+	 * The keys on each level may be either integers or strings.
+	 *
+	 * @param array $data Organized as 2-d
+	 *    array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
+	 * @param string $baseKey Field name to match the base-level keys to (eg 'pl_namespace')
+	 * @param string $subKey Field name to match the sub-level keys to (eg 'pl_title')
+	 * @return string|bool SQL fragment, or false if no items in array
+	 */
+	public function makeWhereFrom2d( $data, $baseKey, $subKey );
+
+	/**
+	 * @param string $field
+	 * @return string
+	 */
+	public function bitNot( $field );
+
+	/**
+	 * @param string $fieldLeft
+	 * @param string $fieldRight
+	 * @return string
+	 */
+	public function bitAnd( $fieldLeft, $fieldRight );
+
+	/**
+	 * @param string $fieldLeft
+	 * @param string $fieldRight
+	 * @return string
+	 */
+	public function bitOr( $fieldLeft, $fieldRight );
+
+	/**
+	 * Build a concatenation list to feed into a SQL query
+	 * @param array $stringList List of raw SQL expressions; caller is
+	 *   responsible for any quoting
+	 * @return string
+	 */
+	public function buildConcat( $stringList );
+
+	/**
+	 * Build a GROUP_CONCAT or equivalent statement for a query.
+	 *
+	 * This is useful for combining a field for several rows into a single string.
+	 * NULL values will not appear in the output, duplicated values will appear,
+	 * and the resulting delimiter-separated values have no defined sort order.
+	 * Code using the results may need to use the PHP unique() or sort() methods.
+	 *
+	 * @param string $delim Glue to bind the results together
+	 * @param string|array $table Table name
+	 * @param string $field Field name
+	 * @param string|array $conds Conditions
+	 * @param string|array $join_conds Join conditions
+	 * @return string SQL text
+	 * @since 1.23
+	 */
+	public function buildGroupConcatField(
+		$delim, $table, $field, $conds = '', $join_conds = array()
+	);
+
+	/**
+	 * Change the current database
+	 *
+	 * @param string $db
+	 * @return bool Success or failure
+	 */
+	public function selectDB( $db );
+
+	/**
+	 * Get the current DB name
+	 * @return string
+	 */
+	public function getDBname();
+
+	/**
+	 * Get the server hostname or IP address
+	 * @return string
+	 */
+	public function getServer();
+
+	/**
+	 * Adds quotes and backslashes.
+	 *
+	 * @param string|Blob $s
+	 * @return string
+	 */
+	public function addQuotes( $s );
+
+	/**
+	 * LIKE statement wrapper, receives a variable-length argument list with
+	 * parts of pattern to match containing either string literals that will be
+	 * escaped or tokens returned by anyChar() or anyString(). Alternatively,
+	 * the function could be provided with an array of aforementioned
+	 * parameters.
+	 *
+	 * Example: $dbr->buildLike( 'My_page_title/', $dbr->anyString() ) returns
+	 * a LIKE clause that searches for subpages of 'My page title'.
+	 * Alternatively:
+	 *   $pattern = array( 'My_page_title/', $dbr->anyString() );
+	 *   $query .= $dbr->buildLike( $pattern );
+	 *
+	 * @since 1.16
+	 * @return string Fully built LIKE statement
+	 */
+	public function buildLike();
+
+	/**
+	 * Returns a token for buildLike() that denotes a '_' to be used in a LIKE query
+	 *
+	 * @return LikeMatch
+	 */
+	public function anyChar();
+
+	/**
+	 * Returns a token for buildLike() that denotes a '%' to be used in a LIKE query
+	 *
+	 * @return LikeMatch
+	 */
+	public function anyString();
+
+	/**
+	 * Returns an appropriately quoted sequence value for inserting a new row.
+	 * MySQL has autoincrement fields, so this is just NULL. But the PostgreSQL
+	 * subclass will return an integer, and save the value for insertId()
+	 *
+	 * Any implementation of this function should *not* involve reusing
+	 * sequence numbers created for rolled-back transactions.
+	 * See http://bugs.mysql.com/bug.php?id=30767 for details.
+	 * @param string $seqName
+	 * @return null|int
+	 */
+	public function nextSequenceValue( $seqName );
+
+	/**
+	 * REPLACE query wrapper.
+	 *
+	 * REPLACE is a very handy MySQL extension, which functions like an INSERT
+	 * except that when there is a duplicate key error, the old row is deleted
+	 * and the new row is inserted in its place.
+	 *
+	 * We simulate this with standard SQL with a DELETE followed by INSERT. To
+	 * perform the delete, we need to know what the unique indexes are so that
+	 * we know how to find the conflicting rows.
+	 *
+	 * 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 string $table The table to replace the row(s) in.
+	 * @param array $uniqueIndexes Is an array of indexes. Each element may be either
+	 *    a field name or an array of field names
+	 * @param array $rows Can be either a single row to insert, or multiple rows,
+	 *    in the same format as for DatabaseBase::insert()
+	 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
+	 */
+	public function replace( $table, $uniqueIndexes, $rows, $fname = __METHOD__ );
+
+	/**
+	 * INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table.
+	 *
+	 * This updates any conflicting rows (according to the unique indexes) using
+	 * the provided SET clause and inserts any remaining (non-conflicted) rows.
+	 *
+	 * $rows 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.
+	 *
+	 * 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.
+	 *
+	 * Usually throws a DBQueryError on failure. If errors are explicitly ignored,
+	 * returns success.
+	 *
+	 * @since 1.22
+	 *
+	 * @param string $table Table name. This will be passed through DatabaseBase::tableName().
+	 * @param array $rows A single row or list of rows to insert
+	 * @param array $uniqueIndexes List of single field names or field name tuples
+	 * @param array $set 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 string $fname Calling function name (use __METHOD__) for logs/profiling
+	 * @throws Exception
+	 * @return bool
+	 */
+	public function upsert(
+		$table, array $rows, array $uniqueIndexes, array $set, $fname = __METHOD__
+	);
+
+	/**
+	 * DELETE where the condition is a join.
+	 *
+	 * MySQL overrides this to use a multi-table DELETE syntax, in other databases
+	 * we use sub-selects
+	 *
+	 * For safety, an empty $conds will not delete everything. If you want to
+	 * delete all rows where the join condition matches, set $conds='*'.
+	 *
+	 * DO NOT put the join condition in $conds.
+	 *
+	 * @param string $delTable The table to delete from.
+	 * @param string $joinTable The other table.
+	 * @param string $delVar The variable to join on, in the first table.
+	 * @param string $joinVar The variable to join on, in the second table.
+	 * @param array $conds Condition array of field names mapped to variables,
+	 *   ANDed together in the WHERE clause
+	 * @param string $fname Calling function name (use __METHOD__) for logs/profiling
+	 * @throws DBUnexpectedError
+	 */
+	public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
+		$fname = __METHOD__
+	);
+
+	/**
+	 * DELETE query wrapper.
+	 *
+	 * @param array $table Table name
+	 * @param string|array $conds Array of conditions. See $conds in DatabaseBase::select()
+	 *   for the format. Use $conds == "*" to delete all rows
+	 * @param string $fname Name of the calling function
+	 * @throws DBUnexpectedError
+	 * @return bool|ResultWrapper
+	 */
+	public function delete( $table, $conds, $fname = __METHOD__ );
+
+	/**
+	 * INSERT SELECT wrapper. Takes data from a SELECT query and inserts it
+	 * into another table.
+	 *
+	 * @param string $destTable The table name to insert into
+	 * @param string|array $srcTable May be either a table name, or an array of table names
+	 *    to include in a join.
+	 *
+	 * @param array $varMap Must be an associative array of the form
+	 *    array( 'dest1' => 'source1', ...). Source items may be literals
+	 *    rather than field names, but strings should be quoted with
+	 *    DatabaseBase::addQuotes()
+	 *
+	 * @param array $conds Condition array. See $conds in DatabaseBase::select() for
+	 *    the details of the format of condition arrays. May be "*" to copy the
+	 *    whole table.
+	 *
+	 * @param string $fname The function name of the caller, from __METHOD__
+	 *
+	 * @param array $insertOptions Options for the INSERT part of the query, see
+	 *    DatabaseBase::insert() for details.
+	 * @param array $selectOptions Options for the SELECT part of the query, see
+	 *    DatabaseBase::select() for details.
+	 *
+	 * @return ResultWrapper
+	 */
+	public function insertSelect( $destTable, $srcTable, $varMap, $conds,
+		$fname = __METHOD__,
+		$insertOptions = array(), $selectOptions = array()
+	);
+
+	/**
+	 * Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries
+	 * within the UNION construct.
+	 * @return bool
+	 */
+	public function unionSupportsOrderAndLimit();
+
+	/**
+	 * Construct a UNION query
+	 * This is used for providing overload point for other DB abstractions
+	 * not compatible with the MySQL syntax.
+	 * @param array $sqls SQL statements to combine
+	 * @param bool $all Use UNION ALL
+	 * @return string SQL fragment
+	 */
+	public function unionQueries( $sqls, $all );
+
+	/**
+	 * Returns an SQL expression for a simple conditional. This doesn't need
+	 * to be overridden unless CASE isn't supported in your DBMS.
+	 *
+	 * @param string|array $cond SQL expression which will result in a boolean value
+	 * @param string $trueVal SQL expression to return if true
+	 * @param string $falseVal SQL expression to return if false
+	 * @return string SQL fragment
+	 */
+	public function conditional( $cond, $trueVal, $falseVal );
+
+	/**
+	 * Returns a comand for str_replace function in SQL query.
+	 * Uses REPLACE() in MySQL
+	 *
+	 * @param string $orig Column to modify
+	 * @param string $old Column to seek
+	 * @param string $new Column to replace with
+	 *
+	 * @return string
+	 */
+	public function strreplace( $orig, $old, $new );
+
+	/**
+	 * Determines how long the server has been up
+	 * STUB
+	 *
+	 * @return int
+	 */
+	public function getServerUptime();
+
+	/**
+	 * Determines if the last failure was due to a deadlock
+	 * STUB
+	 *
+	 * @return bool
+	 */
+	public function wasDeadlock();
+
+	/**
+	 * Determines if the last failure was due to a lock timeout
+	 * STUB
+	 *
+	 * @return bool
+	 */
+	public function wasLockTimeout();
+
+	/**
+	 * Determines if the last query error was something that should be dealt
+	 * with by pinging the connection and reissuing the query.
+	 * STUB
+	 *
+	 * @return bool
+	 */
+	public function wasErrorReissuable();
+
+	/**
+	 * Determines if the last failure was due to the database being read-only.
+	 * STUB
+	 *
+	 * @return bool
+	 */
+	public function wasReadOnlyError();
+
+	/**
+	 * Wait for the slave to catch up to a given master position.
+	 *
+	 * @param DBMasterPos $pos
+	 * @param int $timeout The maximum number of seconds to wait for
+	 *   synchronisation
+	 * @return int Zero if the slave was past that position already,
+	 *   greater than zero if we waited for some period of time, less than
+	 *   zero if we timed out.
+	 */
+	public function masterPosWait( DBMasterPos $pos, $timeout );
+
+	/**
+	 * Get the replication position of this slave
+	 *
+	 * @return DBMasterPos|bool False if this is not a slave.
+	 */
+	public function getSlavePos();
+
+	/**
+	 * Get the position of this master
+	 *
+	 * @return DBMasterPos|bool False if this is not a master
+	 */
+	public function getMasterPos();
+
+	/**
+	 * Run an anonymous function as soon as there is no transaction pending.
+	 * If there is a transaction and it is rolled back, then the callback is cancelled.
+	 * Queries in the function will run in AUTO-COMMIT mode unless there are begin() calls.
+	 * Callbacks must commit any transactions that they begin.
+	 *
+	 * This is useful for updates to different systems or when separate transactions are needed.
+	 * For example, one might want to enqueue jobs into a system outside the database, but only
+	 * after the database is updated so that the jobs will see the data when they actually run.
+	 * It can also be used for updates that easily cause deadlocks if locks are held too long.
+	 *
+	 * @param callable $callback
+	 * @since 1.20
+	 */
+	public function onTransactionIdle( $callback );
+
+	/**
+	 * Run an anonymous function before the current transaction commits or now if there is none.
+	 * If there is a transaction and it is rolled back, then the callback is cancelled.
+	 * Callbacks must not start nor commit any transactions.
+	 *
+	 * This is useful for updates that easily cause deadlocks if locks are held too long
+	 * but where atomicity is strongly desired for these updates and some related updates.
+	 *
+	 * @param callable $callback
+	 * @since 1.22
+	 */
+	public function onTransactionPreCommitOrIdle( $callback );
+
+	/**
+	 * Begin an atomic section of statements
+	 *
+	 * If a transaction has been started already, just keep track of the given
+	 * section name to make sure the transaction is not committed pre-maturely.
+	 * This function can be used in layers (with sub-sections), so use a stack
+	 * to keep track of the different atomic sections. If there is no transaction,
+	 * start one implicitly.
+	 *
+	 * The goal of this function is to create an atomic section of SQL queries
+	 * without having to start a new transaction if it already exists.
+	 *
+	 * Atomic sections are more strict than transactions. With transactions,
+	 * attempting to begin a new transaction when one is already running results
+	 * in MediaWiki issuing a brief warning and doing an implicit commit. All
+	 * atomic levels *must* be explicitly closed using DatabaseBase::endAtomic(),
+	 * and any database transactions cannot be began or committed until all atomic
+	 * levels are closed. There is no such thing as implicitly opening or closing
+	 * an atomic section.
+	 *
+	 * @since 1.23
+	 * @param string $fname
+	 * @throws DBError
+	 */
+	public function startAtomic( $fname = __METHOD__ );
+
+	/**
+	 * Ends an atomic section of SQL statements
+	 *
+	 * Ends the next section of atomic SQL statements and commits the transaction
+	 * if necessary.
+	 *
+	 * @since 1.23
+	 * @see DatabaseBase::startAtomic
+	 * @param string $fname
+	 * @throws DBError
+	 */
+	public function endAtomic( $fname = __METHOD__ );
+
+	/**
+	 * Begin a transaction. If a transaction is already in progress,
+	 * that transaction will be committed before the new transaction is started.
+	 *
+	 * Note that when the DBO_TRX flag is set (which is usually the case for web
+	 * requests, but not for maintenance scripts), any previous database query
+	 * will have started a transaction automatically.
+	 *
+	 * Nesting of transactions is not supported. Attempts to nest transactions
+	 * will cause a warning, unless the current transaction was started
+	 * automatically because of the DBO_TRX flag.
+	 *
+	 * @param string $fname
+	 * @throws DBError
+	 */
+	public function begin( $fname = __METHOD__ );
+
+	/**
+	 * Commits a transaction previously started using begin().
+	 * If no transaction is in progress, a warning is issued.
+	 *
+	 * Nesting of transactions is not supported.
+	 *
+	 * @param string $fname
+	 * @param string $flush Flush flag, set to 'flush' to disable warnings about
+	 *   explicitly committing implicit transactions, or calling commit when no
+	 *   transaction is in progress. This will silently break any ongoing
+	 *   explicit transaction. Only set the flush flag if you are sure that it
+	 *   is safe to ignore these warnings in your context.
+	 * @throws DBUnexpectedError
+	 */
+	public function commit( $fname = __METHOD__, $flush = '' );
+
+	/**
+	 * Rollback a transaction previously started using begin().
+	 * If no transaction is in progress, a warning is issued.
+	 *
+	 * No-op on non-transactional databases.
+	 *
+	 * @param string $fname
+	 * @param string $flush Flush flag, set to 'flush' to disable warnings about
+	 *   calling rollback when no transaction is in progress. This will silently
+	 *   break any ongoing explicit transaction. Only set the flush flag if you
+	 *   are sure that it is safe to ignore these warnings in your context.
+	 * @throws DBUnexpectedError
+	 * @since 1.23 Added $flush parameter
+	 */
+	public function rollback( $fname = __METHOD__, $flush = '' );
+
+	/**
+	 * List all tables on the database
+	 *
+	 * @param string $prefix Only show tables with this prefix, e.g. mw_
+	 * @param string $fname Calling function name
+	 * @throws MWException
+	 * @return array
+	 */
+	public function listTables( $prefix = null, $fname = __METHOD__ );
+
+	/**
+	 * Convert a timestamp in one of the formats accepted by wfTimestamp()
+	 * to the format used for inserting into timestamp fields in this DBMS.
+	 *
+	 * The result is unquoted, and needs to be passed through addQuotes()
+	 * before it can be included in raw SQL.
+	 *
+	 * @param string|int $ts
+	 *
+	 * @return string
+	 */
+	public function timestamp( $ts = 0 );
+
+	/**
+	 * Convert a timestamp in one of the formats accepted by wfTimestamp()
+	 * to the format used for inserting into timestamp fields in this DBMS. If
+	 * NULL is input, it is passed through, allowing NULL values to be inserted
+	 * into timestamp fields.
+	 *
+	 * The result is unquoted, and needs to be passed through addQuotes()
+	 * before it can be included in raw SQL.
+	 *
+	 * @param string|int $ts
+	 *
+	 * @return string
+	 */
+	public function timestampOrNull( $ts = null );
+
+	/**
+	 * Take the result from a query, and wrap it in a ResultWrapper if
+	 * necessary. Boolean values are passed through as is, to indicate success
+	 * of write queries or failure.
+	 *
+	 * Once upon a time, DatabaseBase::query() returned a bare MySQL result
+	 * resource, and it was necessary to call this function to convert it to
+	 * a wrapper. Nowadays, raw database objects are never exposed to external
+	 * callers, so this is unnecessary in external code. For compatibility with
+	 * old code, ResultWrapper objects are passed through unaltered.
+	 *
+	 * @param bool|ResultWrapper|resource $result
+	 * @return bool|ResultWrapper
+	 */
+	public function resultObject( $result );
+
+	/**
+	 * Ping the server and try to reconnect if it there is no connection
+	 *
+	 * @return bool Success or failure
+	 */
+	public function ping();
+
+	/**
+	 * Get slave lag. Currently supported only by MySQL.
+	 *
+	 * Note that this function will generate a fatal error on many
+	 * installations. Most callers should use LoadBalancer::safeGetLag()
+	 * instead.
+	 *
+	 * @return int Database replication lag in seconds
+	 */
+	public function getLag();
+
+	/**
+	 * Return the maximum number of items allowed in a list, or 0 for unlimited.
+	 *
+	 * @return int
+	 */
+	public function maxListLen();
+
+	/**
+	 * Some DBMSs have a special format for inserting into blob fields, they
+	 * don't allow simple quoted strings to be inserted. To insert into such
+	 * a field, pass the data through this function before passing it to
+	 * DatabaseBase::insert().
+	 *
+	 * @param string $b
+	 * @return string
+	 */
+	public function encodeBlob( $b );
+
+	/**
+	 * Some DBMSs return a special placeholder object representing blob fields
+	 * in result objects. Pass the object through this function to return the
+	 * original string.
+	 *
+	 * @param string|Blob $b
+	 * @return string
+	 */
+	public function decodeBlob( $b );
+
+	/**
+	 * Override database's default behavior. $options include:
+	 *     'connTimeout' : Set the connection timeout value in seconds.
+	 *                     May be useful for very long batch queries such as
+	 *                     full-wiki dumps, where a single query reads out over
+	 *                     hours or days.
+	 *
+	 * @param array $options
+	 * @return void
+	 */
+	public function setSessionOptions( array $options );
+
+	/**
+	 * Set variables to be used in sourceFile/sourceStream, in preference to the
+	 * ones in $GLOBALS. If an array is set here, $GLOBALS will not be used at
+	 * all. If it's set to false, $GLOBALS will be used.
+	 *
+	 * @param bool|array $vars Mapping variable name to value.
+	 */
+	public function setSchemaVars( $vars );
+
+	/**
+	 * Check to see if a named lock is available (non-blocking)
+	 *
+	 * @param string $lockName Name of lock to poll
+	 * @param string $method Name of method calling us
+	 * @return bool
+	 * @since 1.20
+	 */
+	public function lockIsFree( $lockName, $method );
+
+	/**
+	 * Acquire a named lock
+	 *
+	 * Named locks are not related to transactions
+	 *
+	 * @param string $lockName Name of lock to aquire
+	 * @param string $method Name of method calling us
+	 * @param int $timeout
+	 * @return bool
+	 */
+	public function lock( $lockName, $method, $timeout = 5 );
+
+	/**
+	 * Release a lock
+	 *
+	 * Named locks are not related to transactions
+	 *
+	 * @param string $lockName Name of lock to release
+	 * @param string $method Name of method calling us
+	 *
+	 * @return int Returns 1 if the lock was released, 0 if the lock was not established
+	 * by this thread (in which case the lock is not released), and NULL if the named
+	 * lock did not exist
+	 */
+	public function unlock( $lockName, $method );
+
+	/**
+	 * Check to see if a named lock used by lock() use blocking queues
+	 *
+	 * @return bool
+	 * @since 1.26
+	 */
+	public function namedLocksEnqueue();
+
+	/**
+	 * Find out when 'infinity' is. Most DBMSes support this. This is a special
+	 * keyword for timestamps in PostgreSQL, and works with CHAR(14) as well
+	 * because "i" sorts after all numbers.
+	 *
+	 * @return string
+	 */
+	public function getInfinity();
+
+	/**
+	 * Encode an expiry time into the DBMS dependent format
+	 *
+	 * @param string $expiry Timestamp for expiry, or the 'infinity' string
+	 * @return string
+	 */
+	public function encodeExpiry( $expiry );
+
+	/**
+	 * Decode an expiry time into a DBMS independent format
+	 *
+	 * @param string $expiry DB timestamp field value for expiry
+	 * @param int $format TS_* constant, defaults to TS_MW
+	 * @return string
+	 */
+	public function decodeExpiry( $expiry, $format = TS_MW );
+
+	/**
+	 * Allow or deny "big selects" for this session only. This is done by setting
+	 * the sql_big_selects session variable.
+	 *
+	 * This is a MySQL-specific feature.
+	 *
+	 * @param bool|string $value True for allow, false for deny, or "default" to
+	 *   restore the initial value
+	 */
+	public function setBigSelects( $value = true );
+}
diff --git a/includes/db/LBFactory.php b/includes/db/LBFactory.php
index 4551e2d7..cf522b20 100644
--- a/includes/db/LBFactory.php
+++ b/includes/db/LBFactory.php
@@ -178,6 +178,15 @@ abstract class LBFactory {
 	}
 
 	/**
+	 * Commit on all connections. Done for two reasons:
+	 * 1. To commit changes to the masters.
+	 * 2. To release the snapshot on all connections, master and slave.
+	 */
+	public function commitAll() {
+		$this->forEachLBCallMethod( 'commitAll' );
+	}
+
+	/**
 	 * Commit changes on all master connections
 	 */
 	public function commitMasterChanges() {
@@ -199,7 +208,7 @@ abstract class LBFactory {
 	 */
 	public function hasMasterChanges() {
 		$ret = false;
-		$this->forEachLB( function ( $lb ) use ( &$ret ) {
+		$this->forEachLB( function ( LoadBalancer $lb ) use ( &$ret ) {
 			$ret = $ret || $lb->hasMasterChanges();
 		} );
 		return $ret;
diff --git a/includes/db/LBFactoryMulti.php b/includes/db/LBFactoryMulti.php
index aa305ab1..92fbccd6 100644
--- a/includes/db/LBFactoryMulti.php
+++ b/includes/db/LBFactoryMulti.php
@@ -232,7 +232,7 @@ class LBFactoryMulti extends LBFactory {
 	public function getMainLB( $wiki = false ) {
 		$section = $this->getSectionForWiki( $wiki );
 		if ( !isset( $this->mainLBs[$section] ) ) {
-			$lb = $this->newMainLB( $wiki, $section );
+			$lb = $this->newMainLB( $wiki );
 			$lb->parentInfo( array( 'id' => "main-$section" ) );
 			$this->chronProt->initLB( $lb );
 			$this->mainLBs[$section] = $lb;
diff --git a/includes/db/LoadBalancer.php b/includes/db/LoadBalancer.php
index d9584e14..52dca087 100644
--- a/includes/db/LoadBalancer.php
+++ b/includes/db/LoadBalancer.php
@@ -60,8 +60,6 @@ class LoadBalancer {
 	private $mLastError = 'Unknown error';
 	/** @var integer Total connections opened */
 	private $connsOpened = 0;
-	/** @var ProcessCacheLRU */
-	private $mProcCache;
 
 	/** @var integer Warn when this many connection are held */
 	const CONN_HELD_WARN_THRESHOLD = 10;
@@ -113,8 +111,6 @@ class LoadBalancer {
 				}
 			}
 		}
-
-		$this->mProcCache = new ProcessCacheLRU( 30 );
 	}
 
 	/**
@@ -214,7 +210,7 @@ class LoadBalancer {
 	 * @return bool|int|string
 	 */
 	public function getReaderIndex( $group = false, $wiki = false ) {
-		global $wgReadOnly, $wgDBtype;
+		global $wgDBtype;
 
 		# @todo FIXME: For now, only go through all this for mysql databases
 		if ( $wgDBtype != 'mysql' ) {
@@ -258,7 +254,7 @@ class LoadBalancer {
 		# meets our criteria
 		$currentLoads = $nonErrorLoads;
 		while ( count( $currentLoads ) ) {
-			if ( $wgReadOnly || $this->mAllowLagged || $laggedSlaveMode ) {
+			if ( $this->mAllowLagged || $laggedSlaveMode ) {
 				$i = ArrayUtils::pickRandom( $currentLoads );
 			} else {
 				$i = false;
@@ -277,8 +273,6 @@ class LoadBalancer {
 				if ( $i === false && count( $currentLoads ) != 0 ) {
 					# All slaves lagged. Switch to read-only mode
 					wfDebugLog( 'replication', "All slaves lagged. Switch to read-only mode" );
-					$wgReadOnly = 'The database has been automatically locked ' .
-						'while the slave database servers catch up to the master';
 					$i = ArrayUtils::pickRandom( $currentLoads );
 					$laggedSlaveMode = true;
 				}
@@ -293,8 +287,8 @@ class LoadBalancer {
 				return false;
 			}
 
-			wfDebugLog( 'connect', __METHOD__ .
-				": Using reader #$i: {$this->mServers[$i]['host']}..." );
+			$serverName = $this->getServerName( $i );
+			wfDebugLog( 'connect', __METHOD__ . ": Using reader #$i: $serverName..." );
 
 			$conn = $this->openConnection( $i, $wiki );
 			if ( !$conn ) {
@@ -330,6 +324,10 @@ class LoadBalancer {
 			}
 			if ( $this->mReadIndex <= 0 && $this->mLoads[$i] > 0 && $group === false ) {
 				$this->mReadIndex = $i;
+				# Record if the generic reader index is in "lagged slave" mode
+				if ( $laggedSlaveMode ) {
+					$this->mLaggedSlaveMode = true;
+				}
 			}
 			$serverName = $this->getServerName( $i );
 			wfDebug( __METHOD__ . ": using server $serverName for group '$group'\n" );
@@ -357,6 +355,37 @@ class LoadBalancer {
 	}
 
 	/**
+	 * Set the master wait position and wait for a "generic" slave to catch up to it
+	 *
+	 * This can be used a faster proxy for waitForAll()
+	 *
+	 * @param DBMasterPos $pos
+	 * @param int $timeout Max seconds to wait; default is mWaitTimeout
+	 * @return bool Success (able to connect and no timeouts reached)
+	 * @since 1.26
+	 */
+	public function waitForOne( $pos, $timeout = null ) {
+		$this->mWaitForPos = $pos;
+
+		$i = $this->mReadIndex;
+		if ( $i <= 0 ) {
+			// Pick a generic slave if there isn't one yet
+			$readLoads = $this->mLoads;
+			unset( $readLoads[$this->getWriterIndex()] ); // slaves only
+			$readLoads = array_filter( $readLoads ); // with non-zero load
+			$i = ArrayUtils::pickRandom( $readLoads );
+		}
+
+		if ( $i > 0 ) {
+			$ok = $this->doWait( $i, true, $timeout );
+		} else {
+			$ok = true; // no applicable loads
+		}
+
+		return $ok;
+	}
+
+	/**
 	 * Set the master wait position and wait for ALL slaves to catch up to it
 	 * @param DBMasterPos $pos
 	 * @param int $timeout Max seconds to wait; default is mWaitTimeout
@@ -429,7 +458,7 @@ class LoadBalancer {
 
 		if ( $result == -1 || is_null( $result ) ) {
 			# Timed out waiting for slave, use master instead
-			$server = $this->mServers[$index]['host'];
+			$server = $server = $this->getServerName( $index );
 			$msg = __METHOD__ . ": Timed out waiting on $server pos {$this->mWaitForPos}";
 			wfDebug( "$msg\n" );
 			wfDebugLog( 'DBPerformance', "$msg:\n" . wfBacktrace( true ) );
@@ -505,7 +534,6 @@ class LoadBalancer {
 		# Now we have an explicit index into the servers array
 		$conn = $this->openConnection( $i, $wiki );
 		if ( !$conn ) {
-
 			return $this->reportConnectionError();
 		}
 
@@ -618,25 +646,32 @@ class LoadBalancer {
 	public function openConnection( $i, $wiki = false ) {
 		if ( $wiki !== false ) {
 			$conn = $this->openForeignConnection( $i, $wiki );
-
-			return $conn;
-		}
-		if ( isset( $this->mConns['local'][$i][0] ) ) {
+		} elseif ( isset( $this->mConns['local'][$i][0] ) ) {
 			$conn = $this->mConns['local'][$i][0];
 		} else {
 			$server = $this->mServers[$i];
 			$server['serverIndex'] = $i;
 			$conn = $this->reallyOpenConnection( $server, false );
+			$serverName = $this->getServerName( $i );
 			if ( $conn->isOpen() ) {
-				wfDebug( "Connected to database $i at {$this->mServers[$i]['host']}\n" );
+				wfDebug( "Connected to database $i at $serverName\n" );
 				$this->mConns['local'][$i][0] = $conn;
 			} else {
-				wfDebug( "Failed to connect to database $i at {$this->mServers[$i]['host']}\n" );
+				wfDebug( "Failed to connect to database $i at $serverName\n" );
 				$this->mErrorConnection = $conn;
 				$conn = false;
 			}
 		}
 
+		if ( $conn && !$conn->isOpen() ) {
+			// Connection was made but later unrecoverably lost for some reason.
+			// Do not return a handle that will just throw exceptions on use,
+			// but let the calling code (e.g. getReaderIndex) try another server.
+			// See DatabaseMyslBase::ping() for how this can happen.
+			$this->mErrorConnection = $conn;
+			$conn = false;
+		}
+
 		return $conn;
 	}
 
@@ -812,8 +847,9 @@ class LoadBalancer {
 
 	/**
 	 * @return int
+	 * @since 1.26
 	 */
-	private function getWriterIndex() {
+	public function getWriterIndex() {
 		return 0;
 	}
 
@@ -854,12 +890,14 @@ class LoadBalancer {
 	 */
 	public function getServerName( $i ) {
 		if ( isset( $this->mServers[$i]['hostName'] ) ) {
-			return $this->mServers[$i]['hostName'];
+			$name = $this->mServers[$i]['hostName'];
 		} elseif ( isset( $this->mServers[$i]['host'] ) ) {
-			return $this->mServers[$i]['host'];
+			$name = $this->mServers[$i]['host'];
 		} else {
-			return '';
+			$name = '';
 		}
+
+		return ( $name != '' ) ? $name : 'localhost';
 	}
 
 	/**
@@ -1096,9 +1134,12 @@ class LoadBalancer {
 	}
 
 	/**
-	 * @return bool
+	 * @return bool Whether the generic connection for reads is highly "lagged"
 	 */
 	public function getLaggedSlaveMode() {
+		# Get a generic reader connection
+		$this->getConnection( DB_SLAVE );
+
 		return $this->mLaggedSlaveMode;
 	}
 
@@ -1195,16 +1236,8 @@ class LoadBalancer {
 			return array( 0 => 0 ); // no replication = no lag
 		}
 
-		if ( $this->mProcCache->has( 'slave_lag', 'times', 1 ) ) {
-			return $this->mProcCache->get( 'slave_lag', 'times' );
-		}
-
 		# Send the request to the load monitor
-		$times = $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
-
-		$this->mProcCache->set( 'slave_lag', 'times', $times );
-
-		return $times;
+		return $this->getLoadMonitor()->getLagTimes( array_keys( $this->mServers ), $wiki );
 	}
 
 	/**
@@ -1231,54 +1264,10 @@ class LoadBalancer {
 
 	/**
 	 * Clear the cache for slag lag delay times
+	 *
+	 * This is only used for testing
 	 */
 	public function clearLagTimeCache() {
-		$this->mProcCache->clear( 'slave_lag' );
-	}
-}
-
-/**
- * Helper class to handle automatically marking connections as reusable (via RAII pattern)
- * as well handling deferring the actual network connection until the handle is used
- *
- * @ingroup Database
- * @since 1.22
- */
-class DBConnRef implements IDatabase {
-	/** @var LoadBalancer */
-	private $lb;
-
-	/** @var DatabaseBase|null */
-	private $conn;
-
-	/** @var array|null */
-	private $params;
-
-	/**
-	 * @param LoadBalancer $lb
-	 * @param DatabaseBase|array $conn Connection or (server index, group, wiki ID) array
-	 */
-	public function __construct( LoadBalancer $lb, $conn ) {
-		$this->lb = $lb;
-		if ( $conn instanceof DatabaseBase ) {
-			$this->conn = $conn;
-		} else {
-			$this->params = $conn;
-		}
-	}
-
-	public function __call( $name, $arguments ) {
-		if ( $this->conn === null ) {
-			list( $db, $groups, $wiki ) = $this->params;
-			$this->conn = $this->lb->getConnection( $db, $groups, $wiki );
-		}
-
-		return call_user_func_array( array( $this->conn, $name ), $arguments );
-	}
-
-	public function __destruct() {
-		if ( $this->conn !== null ) {
-			$this->lb->reuseConnection( $this->conn );
-		}
+		$this->getLoadMonitor()->clearCaches();
 	}
 }
diff --git a/includes/db/LoadMonitor.php b/includes/db/LoadMonitor.php
index 91840dd9..4975ea19 100644
--- a/includes/db/LoadMonitor.php
+++ b/includes/db/LoadMonitor.php
@@ -64,90 +64,3 @@ class LoadMonitorNull implements LoadMonitor {
 		return array_fill_keys( $serverIndexes, 0 );
 	}
 }
-
-/**
- * Basic MySQL load monitor with no external dependencies
- * Uses memcached to cache the replication lag for a short time
- *
- * @ingroup Database
- */
-class LoadMonitorMySQL implements LoadMonitor {
-	/** @var LoadBalancer */
-	public $parent;
-	/** @var BagOStuff */
-	protected $cache;
-
-	public function __construct( $parent ) {
-		global $wgMemc;
-
-		$this->parent = $parent;
-		$this->cache = $wgMemc ?: wfGetMainCache();
-	}
-
-	public function scaleLoads( &$loads, $group = false, $wiki = false ) {
-	}
-
-	public function getLagTimes( $serverIndexes, $wiki ) {
-		if ( count( $serverIndexes ) == 1 && reset( $serverIndexes ) == 0 ) {
-			// Single server only, just return zero without caching
-			return array( 0 => 0 );
-		}
-
-		$expiry = 5;
-		$requestRate = 10;
-
-		$cache = $this->cache;
-		$masterName = $this->parent->getServerName( 0 );
-		$memcKey = wfMemcKey( 'lag_times', $masterName );
-		$times = $cache->get( $memcKey );
-		if ( is_array( $times ) ) {
-			# Randomly recache with probability rising over $expiry
-			$elapsed = time() - $times['timestamp'];
-			$chance = max( 0, ( $expiry - $elapsed ) * $requestRate );
-			if ( mt_rand( 0, $chance ) != 0 ) {
-				unset( $times['timestamp'] ); // hide from caller
-
-				return $times;
-			}
-			wfIncrStats( 'lag_cache_miss_expired' );
-		} else {
-			wfIncrStats( 'lag_cache_miss_absent' );
-		}
-
-		# Cache key missing or expired
-		if ( $cache->add( "$memcKey:lock", 1, 10 ) ) {
-			# Let this process alone update the cache value
-			$unlocker = new ScopedCallback( function () use ( $cache, $memcKey ) {
-				$cache->delete( $memcKey );
-			} );
-		} elseif ( is_array( $times ) ) {
-			# Could not acquire lock but an old cache exists, so use it
-			unset( $times['timestamp'] ); // hide from caller
-
-			return $times;
-		}
-
-		$times = array();
-		foreach ( $serverIndexes as $i ) {
-			if ( $i == 0 ) { # Master
-				$times[$i] = 0;
-			} elseif ( false !== ( $conn = $this->parent->getAnyOpenConnection( $i ) ) ) {
-				$times[$i] = $conn->getLag();
-			} elseif ( false !== ( $conn = $this->parent->openConnection( $i, $wiki ) ) ) {
-				$times[$i] = $conn->getLag();
-				// Close the connection to avoid sleeper connections piling up.
-				// Note that the caller will pick one of these DBs and reconnect,
-				// which is slightly inefficient, but this only matters for the lag
-				// time cache miss cache, which is far less common that cache hits.
-				$this->parent->closeConnection( $conn );
-			}
-		}
-
-		# Add a timestamp key so we know when it was cached
-		$times['timestamp'] = time();
-		$cache->set( $memcKey, $times, $expiry + 10 );
-		unset( $times['timestamp'] ); // hide from caller
-
-		return $times;
-	}
-}
diff --git a/includes/db/LoadMonitorMySQL.php b/includes/db/LoadMonitorMySQL.php
new file mode 100644
index 00000000..30084190
--- /dev/null
+++ b/includes/db/LoadMonitorMySQL.php
@@ -0,0 +1,124 @@
+<?php
+/**
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Database
+ */
+
+/**
+ * Basic MySQL load monitor with no external dependencies
+ * Uses memcached to cache the replication lag for a short time
+ *
+ * @ingroup Database
+ */
+class LoadMonitorMySQL implements LoadMonitor {
+	/** @var LoadBalancer */
+	public $parent;
+	/** @var BagOStuff */
+	protected $srvCache;
+	/** @var BagOStuff */
+	protected $mainCache;
+
+	public function __construct( $parent ) {
+		$this->parent = $parent;
+
+		$this->srvCache = ObjectCache::newAccelerator( 'hash' );
+		$this->mainCache = wfGetMainCache();
+	}
+
+	public function scaleLoads( &$loads, $group = false, $wiki = false ) {
+	}
+
+	public function getLagTimes( $serverIndexes, $wiki ) {
+		if ( count( $serverIndexes ) == 1 && reset( $serverIndexes ) == 0 ) {
+			# Single server only, just return zero without caching
+			return array( 0 => 0 );
+		}
+
+		$key = $this->getLagTimeCacheKey();
+		# Randomize TTLs to reduce stampedes (4.0 - 5.0 sec)
+		$ttl = mt_rand( 4e6, 5e6 ) / 1e6;
+		# Keep keys around longer as fallbacks
+		$staleTTL = 60;
+
+		# (a) Check the local APC cache
+		$value = $this->srvCache->get( $key );
+		if ( $value && $value['timestamp'] > ( microtime( true ) - $ttl ) ) {
+			wfDebugLog( 'replication',  __FUNCTION__ . ": got lag times ($key) from local cache" );
+			return $value['lagTimes']; // cache hit
+		}
+		$staleValue = $value ?: false;
+
+		# (b) Check the shared cache and backfill APC
+		$value = $this->mainCache->get( $key );
+		if ( $value && $value['timestamp'] > ( microtime( true ) - $ttl ) ) {
+			$this->srvCache->set( $key, $value, $staleTTL );
+			wfDebugLog( 'replication',  __FUNCTION__ . ": got lag times ($key) from main cache" );
+
+			return $value['lagTimes']; // cache hit
+		}
+		$staleValue = $value ?: $staleValue;
+
+		# (c) Cache key missing or expired; regenerate and backfill
+		if ( $this->mainCache->lock( $key, 0, 10 ) ) {
+			# Let this process alone update the cache value
+			$cache = $this->mainCache;
+			/** @noinspection PhpUnusedLocalVariableInspection */
+			$unlocker = new ScopedCallback( function () use ( $cache, $key ) {
+				$cache->unlock( $key );
+			} );
+		} elseif ( $staleValue ) {
+			# Could not acquire lock but an old cache exists, so use it
+			return $staleValue['lagTimes'];
+		}
+
+		$lagTimes = array();
+		foreach ( $serverIndexes as $i ) {
+			if ( $i == 0 ) { # Master
+				$lagTimes[$i] = 0;
+			} elseif ( false !== ( $conn = $this->parent->getAnyOpenConnection( $i ) ) ) {
+				$lagTimes[$i] = $conn->getLag();
+			} elseif ( false !== ( $conn = $this->parent->openConnection( $i, $wiki ) ) ) {
+				$lagTimes[$i] = $conn->getLag();
+				# Close the connection to avoid sleeper connections piling up.
+				# Note that the caller will pick one of these DBs and reconnect,
+				# which is slightly inefficient, but this only matters for the lag
+				# time cache miss cache, which is far less common that cache hits.
+				$this->parent->closeConnection( $conn );
+			}
+		}
+
+		# Add a timestamp key so we know when it was cached
+		$value = array( 'lagTimes' => $lagTimes, 'timestamp' => microtime( true ) );
+		$this->mainCache->set( $key, $value, $staleTTL );
+		$this->srvCache->set( $key, $value, $staleTTL );
+		wfDebugLog( 'replication',  __FUNCTION__ . ": re-calculated lag times ($key)" );
+
+		return $value['lagTimes'];
+	}
+
+	public function clearCaches() {
+		$key = $this->getLagTimeCacheKey();
+		$this->srvCache->delete( $key );
+		$this->mainCache->delete( $key );
+	}
+
+	private function getLagTimeCacheKey() {
+		# Lag is per-server, not per-DB, so key on the master DB name
+		return wfGlobalCacheKey( 'lag-times', $this->parent->getServerName( 0 ) );
+	}
+}