Basic database interface for live and lazy-loaded DB handles. More...

Inheritance diagram for IDatabase:

Public Member Functions
	addQuotes ($s)
	Adds quotes and backslashes. More...

	affectedRows ()
	Get the number of rows affected by the last write query. More...

	anyChar ()
	Returns a token for buildLike() that denotes a '_' to be used in a LIKE query. More...

	anyString ()
	Returns a token for buildLike() that denotes a '' to be used in a LIKE query. More...

	begin ($fname=__METHOD__)
	Begin a transaction. More...

	bitAnd ($fieldLeft, $fieldRight)

	bitNot ($field)

	bitOr ($fieldLeft, $fieldRight)

	bufferResults ($buffer=null)
	Turns buffering of SQL result sets on (true) or off (false). More...

	buildConcat ($stringList)
	Build a concatenation list to feed into a SQL query. More...

	buildGroupConcatField ($delim, $table, $field, $conds= '', $join_conds=[])
	Build a GROUP_CONCAT or equivalent statement for a query. More...

	buildLike ()
	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(). More...

	clearFlag ($flag)
	Clear a flag for this connection. More...

	close ()
	Closes a database connection. More...

	commit ($fname=__METHOD__, $flush= '')
	Commits a transaction previously started using begin(). More...

	conditional ($cond, $trueVal, $falseVal)
	Returns an SQL expression for a simple conditional. More...

	dataSeek ($res, $row)
	Change the position of the cursor in a result object. More...

	dbSchema ($schema=null)
	Get/set the db schema. More...

	decodeBlob ($b)
	Some DBMSs return a special placeholder object representing blob fields in result objects. More...

	decodeExpiry ($expiry, $format=TS_MW)
	Decode an expiry time into a DBMS independent format. More...

	delete ($table, $conds, $fname=__METHOD__)
	DELETE query wrapper. More...

	deleteJoin ($delTable, $joinTable, $delVar, $joinVar, $conds, $fname=__METHOD__)
	DELETE where the condition is a join. More...

	doAtomicSection ($fname, callable $callback)
	Run a callback to do an atomic set of updates for this database. More...

	doneWrites ()
	Returns true if the connection may have been used for write queries. More...

	encodeBlob ($b)
	Some DBMSs have a special format for inserting into blob fields, they don't allow simple quoted strings to be inserted. More...

	encodeExpiry ($expiry)
	Encode an expiry time into the DBMS dependent format. More...

	endAtomic ($fname=__METHOD__)
	Ends an atomic section of SQL statements. More...

	estimateRowCount ($table, $vars= '*', $conds= '', $fname=__METHOD__, $options=[])
	Estimate the number of rows in dataset. More...

	fetchObject ($res)
	Fetch the next row from the given result object, in object form. More...

	fetchRow ($res)
	Fetch the next row from the given result object, in associative array form. More...

	fieldExists ($table, $field, $fname=__METHOD__)
	Determines whether a field exists in a table. More...

	fieldInfo ($table, $field)
	mysql_fetch_field() wrapper Returns false if the field doesn't exist More...

	fieldName ($res, $n)
	Get a field name in a result object. More...

	freeResult ($res)
	Free a result object returned by query() or select(). More...

	getDBname ()
	Get the current DB name. More...

	getFlag ($flag)
	Returns a boolean whether the flag $flag is set for this connection. More...

	getInfinity ()
	Find out when 'infinity' is. More...

	getLag ()
	Get slave lag. More...

	getLBInfo ($name=null)
	Get properties passed down from the server info array of the load balancer. More...

	getMasterPos ()
	Get the position of this master. More...

	getProperty ($name)
	General read-only accessor. More...

	getScopedLockAndFlush ($lockKey, $fname, $timeout)
	Acquire a named lock, flush any transaction, and return an RAII style unlocker object. More...

	getServer ()
	Get the server hostname or IP address. More...

	getServerInfo ()
	A string describing the current software version, and possibly other details in a user-friendly way. More...

	getServerUptime ()
	Determines how long the server has been up STUB. More...

	getServerVersion ()
	A string describing the current software version, like from mysql_get_server_info(). More...

	getSessionLagStatus ()
	Get the slave lag when the current transaction started or a general lag estimate if not transaction is active. More...

	getSlavePos ()
	Get the replication position of this slave. More...

	getSoftwareLink ()
	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. More...

	getType ()
	Get the type of the DBMS, as it appears in $wgDBtype. More...

	getWikiID ()

	implicitGroupby ()
	Returns true if this database does an implicit sort when doing GROUP BY. More...

	implicitOrderby ()
	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. More...

	indexExists ($table, $index, $fname=__METHOD__)
	Determines whether an index exists Usually throws a DBQueryError on failure If errors are explicitly ignored, returns NULL on failure. More...

	indexUnique ($table, $index)
	Determines if a given index is unique. More...

	insert ($table, $a, $fname=__METHOD__, $options=[])
	INSERT wrapper, inserts an array into a table. More...

	insertId ()
	Get the inserted value of an auto-increment row. More...

	insertSelect ($destTable, $srcTable, $varMap, $conds, $fname=__METHOD__, $insertOptions=[], $selectOptions=[])
	INSERT SELECT wrapper. More...

	isOpen ()
	Is a connection to the database open? More...

	isReadOnly ()

	lastDoneWrites ()
	Returns the last time the connection may have been used for write queries. More...

	lastErrno ()
	Get the last error number. More...

	lastError ()
	Get a description of the last error. More...

	lastQuery ()
	Return the last query that went through IDatabase::query() More...

	listTables ($prefix=null, $fname=__METHOD__)
	List all tables on the database. More...

	lock ($lockName, $method, $timeout=5)
	Acquire a named lock. More...

	lockIsFree ($lockName, $method)
	Check to see if a named lock is available (non-blocking) More...

	makeList ($a, $mode=LIST_COMMA)
	Makes an encoded list of strings from an array. More...

	makeWhereFrom2d ($data, $baseKey, $subKey)
	Build a partial where clause from a 2-d array such as used for LinkBatch. More...

	masterPosWait (DBMasterPos $pos, $timeout)
	Wait for the slave to catch up to a given master position. More...

	maxListLen ()
	Return the maximum number of items allowed in a list, or 0 for unlimited. More...

	namedLocksEnqueue ()
	Check to see if a named lock used by lock() use blocking queues. More...

	nextSequenceValue ($seqName)
	Returns an appropriately quoted sequence value for inserting a new row. More...

	numFields ($res)
	Get the number of fields in a result object. More...

	numRows ($res)
	Get the number of rows in a result object. More...

	onTransactionIdle (callable $callback)
	Run a callback as soon as there is no transaction pending. More...

	onTransactionPreCommitOrIdle (callable $callback)
	Run a callback before the current transaction commits or now if there is none. More...

	onTransactionResolution (callable $callback)
	Run a callback as soon as the current transaction commits or rolls back. More...

	open ($server, $user, $password, $dbName)
	Open a connection to the database. More...

	pendingWriteCallers ()
	Get the list of method names that did write queries for this transaction. More...

	pendingWriteQueryDuration ()
	Get the time spend running write queries for this transaction. More...

	ping ()
	Ping the server and try to reconnect if it there is no connection. More...

	query ($sql, $fname=__METHOD__, $tempIgnore=false)
	Run an SQL query and return the result. More...

	replace ($table, $uniqueIndexes, $rows, $fname=__METHOD__)
	REPLACE query wrapper. More...

	reportConnectionError ($error= 'Unknown error')

	reportQueryError ($error, $errno, $sql, $fname, $tempIgnore=false)
	Report a query error. More...

	rollback ($fname=__METHOD__, $flush= '')
	Rollback a transaction previously started using begin(). More...

	select ($table, $vars, $conds= '', $fname=__METHOD__, $options=[], $join_conds=[])
	Execute a SELECT query constructed using the various parameters provided. More...

	selectDB ($db)
	Change the current database. More...

	selectField ($table, $var, $cond= '', $fname=__METHOD__, $options=[])
	A SELECT wrapper which returns a single field from a single result row. More...

	selectFieldValues ($table, $var, $cond= '', $fname=__METHOD__, $options=[])
	A SELECT wrapper which returns a list of single field values from result rows. More...

	selectRow ($table, $vars, $conds, $fname=__METHOD__, $options=[], $join_conds=[])
	Single row SELECT wrapper. More...

	selectRowCount ($tables, $vars= '*', $conds= '', $fname=__METHOD__, $options=[], $join_conds=[])
	Get the number of rows in dataset. More...

	selectSQLText ($table, $vars, $conds= '', $fname=__METHOD__, $options=[], $join_conds=[])
	The equivalent of IDatabase::select() except that the constructed SQL is returned, instead of being immediately executed. More...

	serverIsReadOnly ()

	setBigSelects ($value=true)
	Allow or deny "big selects" for this session only. More...

	setFlag ($flag)
	Set a flag for this connection. More...

	setLBInfo ($name, $value=null)
	Set the LB info array, or a member of it. More...

	setSchemaVars ($vars)
	Set variables to be used in sourceFile/sourceStream, in preference to the ones in $GLOBALS. More...

	setSessionOptions (array $options)
	Override database's default behavior. More...

	startAtomic ($fname=__METHOD__)
	Begin an atomic section of statements. More...

	strreplace ($orig, $old, $new)
	Returns a comand for str_replace function in SQL query. More...

	tableExists ($table, $fname=__METHOD__)
	Query whether a given table exists. More...

	tablePrefix ($prefix=null)
	Get/set the table prefix. More...

	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. More...

	timestampOrNull ($ts=null)
	Convert a timestamp in one of the formats accepted by wfTimestamp() to the format used for inserting into timestamp fields in this DBMS. More...

	trxLevel ()
	Gets the current transaction level. More...

	trxTimestamp ()
	Get the UNIX timestamp of the time that the transaction was established. More...

	unionQueries ($sqls, $all)
	Construct a UNION query This is used for providing overload point for other DB abstractions not compatible with the MySQL syntax. More...

	unionSupportsOrderAndLimit ()
	Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries within the UNION construct. More...

	unlock ($lockName, $method)
	Release a lock. More...

	update ($table, $values, $conds, $fname=__METHOD__, $options=[])
	UPDATE wrapper. More...

	upsert ($table, array $rows, array $uniqueIndexes, array $set, $fname=__METHOD__)
	INSERT ON DUPLICATE KEY UPDATE wrapper, upserts an array into a table. More...

	wasDeadlock ()
	Determines if the last failure was due to a deadlock STUB. More...

	wasErrorReissuable ()
	Determines if the last query error was something that should be dealt with by pinging the connection and reissuing the query. More...

	wasLockTimeout ()
	Determines if the last failure was due to a lock timeout STUB. More...

	wasReadOnlyError ()
	Determines if the last failure was due to the database being read-only. More...

	writesOrCallbacksPending ()
	Returns true if there is a transaction open with possible write queries or transaction pre-commit/idle callbacks waiting on it to finish. More...

	writesPending ()

Public Attributes
const	TRIGGER_COMMIT = 2

const	TRIGGER_IDLE = 1

const	TRIGGER_ROLLBACK = 3

Detailed Description

Basic database interface for live and lazy-loaded DB handles.

Todo:

: loosen up DB classes from MWException

Note: : IDatabase and DBConnRef should be updated to reflect any changes

Definition at line 35 of file IDatabase.php.

Member Function Documentation

IDatabase::addQuotes ( $s )

Adds quotes and backslashes.

Parameters

string | Blob $s

Returns: string

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, DatabaseMssql, DatabaseSqlite, and DBConnRef.

Referenced by DBFileJournal\doGetChangeEntries(), DBFileJournal\doGetPositionAtTime(), DBFileJournal\doPurgeOldLogs(), WatchedItemStore\getVisitingWatchersCondition(), Title\invalidateCache(), Block\purgeExpired(), Title\purgeExpiredRestrictions(), and SpecialWhatLinksHere\showIndirectLinks().

IDatabase::affectedRows ( )

Get the number of rows affected by the last write query.

See Also: http://www.php.net/mysql_affected_rows

Returns: int

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMssql, FakeDatabase, DBConnRef, DatabaseMysqli, DatabaseTestHelper, DatabaseMysql, and FakeDatabaseMysqlBase.

Referenced by DatabaseBase\query().

IDatabase::anyChar ( )

Returns a token for buildLike() that denotes a '_' to be used in a LIKE query.

Returns: LikeMatch

Implemented in DatabaseBase, and DBConnRef.

IDatabase::anyString ( )

Returns a token for buildLike() that denotes a '' to be used in a LIKE query.

Returns: LikeMatch

Implemented in DatabaseBase, and DBConnRef.

IDatabase::begin ( $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.

Parameters

string $fname

Exceptions

DBError

Implemented in DatabaseBase, and DBConnRef.

Referenced by Maintenance\beginTransaction().

IDatabase::bitAnd	(	$fieldLeft,
		$fieldRight
	)

Parameters

string	$fieldLeft
string	$fieldRight

Returns: string

Implemented in DatabaseBase, DatabaseOracle, and DBConnRef.

IDatabase::bitNot ( $field )

Parameters

string $field

Returns: string

Implemented in DatabaseBase, DatabaseOracle, and DBConnRef.

IDatabase::bitOr	(	$fieldLeft,
		$fieldRight
	)

Parameters

string	$fieldLeft
string	$fieldRight

Returns: string

Implemented in DatabaseBase, DatabaseOracle, and DBConnRef.

IDatabase::bufferResults ( $buffer = null )

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.

Parameters

null | bool $buffer

Returns: null|bool The previous value of the flag

Implemented in DatabaseBase, and DBConnRef.

IDatabase::buildConcat ( $stringList )

Build a concatenation list to feed into a SQL query.

Parameters

array $stringList List of raw SQL expressions; caller is responsible for any quoting

Returns: string

Implemented in DatabaseBase, DatabasePostgres, DatabaseMssql, DatabaseSqlite, and DBConnRef.

IDatabase::buildGroupConcatField	(	$delim,
		$table,
		$field,
		$conds = `''`,
		$join_conds = `[]`
	)

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.

Parameters

string	$delim	Glue to bind the results together
string \| array	$table	Table name
string	$field	Field name
string \| array	$conds	Conditions
string \| array	$join_conds	Join conditions

Returns: string SQL text

Since: 1.23

Implemented in DatabaseBase, DatabaseOracle, DatabaseMssql, DatabaseSqlite, and DBConnRef.

IDatabase::buildLike ( )

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

Returns: string Fully built LIKE statement

Implemented in DatabaseBase, DatabaseMssql, DatabaseSqlite, and DBConnRef.

IDatabase::clearFlag ( $flag )

Clear a flag for this connection.

Parameters

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

Implemented in DatabaseBase, DBConnRef, and FakeDatabase.

IDatabase::close ( )

Closes a database connection.

if it is open : commits any open transactions

Exceptions

MWException

Returns: bool Operation success. true if already closed.

Implemented in DatabaseBase, and DBConnRef.

IDatabase::commit	(	$fname = `__METHOD__`,
		$flush = `''`
	)

Commits a transaction previously started using begin().

If no transaction is in progress, a warning is issued.

Nesting of transactions is not supported.

Parameters

string	$fname
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 trigger an exception if there is an ongoing explicit transaction.

Only set the flush flag if you are sure that these warnings are not applicable, and no explicit transactions are open.

Exceptions

DBUnexpectedError

Implemented in DatabaseBase, and DBConnRef.

Referenced by Maintenance\commitTransaction().

IDatabase::conditional	(	$cond,
		$trueVal,
		$falseVal
	)

Returns an SQL expression for a simple conditional.

This doesn't need to be overridden unless CASE isn't supported in your DBMS.

Parameters

string \| array	$cond	SQL expression which will result in a boolean value
string	$trueVal	SQL expression to return if true
string	$falseVal	SQL expression to return if false

Returns: string SQL fragment

Implemented in DatabaseBase, and DBConnRef.

IDatabase::dataSeek	(	$res,
		$row
	)

Change the position of the cursor in a result object.

See Also: http://www.php.net/mysql_data_seek

Parameters

mixed	$res	A SQL result
int	$row

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, FakeDatabase, and DatabaseTestHelper.

IDatabase::dbSchema ( $schema = null )

Get/set the db schema.

Parameters

string $schema The database schema to set, or omitted to leave it unchanged.

Returns: string The previous db schema.

Implemented in DatabaseBase, and DBConnRef.

IDatabase::decodeBlob ( $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.

Parameters

string | Blob $b

Returns: string

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, DatabaseSqlite, and DBConnRef.

IDatabase::decodeExpiry	(	$expiry,
		$format = `TS_MW`
	)

Decode an expiry time into a DBMS independent format.

Parameters

string	$expiry	DB timestamp field value for expiry
int	$format	TS_* constant, defaults to TS_MW

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::delete	(	$table,
		$conds,
		$fname = `__METHOD__`
	)

DELETE query wrapper.

Parameters

array	$table	Table name
string \| array	$conds	Array of conditions. See $conds in IDatabase::select() for the format. Use $conds == "*" to delete all rows
string	$fname	Name of the calling function

Exceptions

DBUnexpectedError

Returns: bool|ResultWrapper

Implemented in DatabaseBase, DatabaseOracle, DatabaseMssql, and DBConnRef.

Referenced by DBFileJournal\doPurgeOldLogs(), Block\purgeExpired(), Title\purgeExpiredRestrictions(), and QueryPage\recache().

IDatabase::deleteJoin	(	$delTable,
		$joinTable,
		$delVar,
		$joinVar,
		$conds,
		$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.

Parameters

string	$delTable	The table to delete from.
string	$joinTable	The other table.
string	$delVar	The variable to join on, in the first table.
string	$joinVar	The variable to join on, in the second table.
array	$conds	Condition array of field names mapped to variables, ANDed together in the WHERE clause
string	$fname	Calling function name (use METHOD) for logs/profiling

Exceptions

DBUnexpectedError

Implemented in DatabaseBase, DatabaseMysqlBase, DatabaseMssql, and DBConnRef.

IDatabase::doAtomicSection	(		$fname,
		callable	$callback
	)

Run a callback to do an atomic set of updates for this database.

The $callback takes the following arguments:

This database object
The value of $fname

If any exception occurs in the callback, then rollback() will be called and the error will be re-thrown. It may also be that the rollback itself fails with an exception before then. In any case, such errors are expected to terminate the request, without any outside caller attempting to catch errors and commit anyway. Note that any rollback undoes all prior atomic section and uncommitted updates, which trashes the current request, requiring an error to be displayed.

This can be an alternative to explicit startAtomic()/endAtomic() calls.

See Also: DatabaseBase::startAtomic; DatabaseBase::endAtomic

Parameters

string	$fname	Caller name (usually METHOD)
callable	$callback	Callback that issues DB updates

Exceptions

DBError
RuntimeException
UnexpectedValueException

Since: 1.27

Implemented in DatabaseBase, and DBConnRef.

IDatabase::doneWrites ( )

Returns true if the connection may have been used for write queries.

Should return true if unsure.

Returns: bool

Implemented in DatabaseBase, and DBConnRef.

IDatabase::encodeBlob ( $b )

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 IDatabase::insert().

Parameters

string $b

Returns: string

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, DatabaseSqlite, and DBConnRef.

IDatabase::encodeExpiry ( $expiry )

Encode an expiry time into the DBMS dependent format.

Parameters

string $expiry Timestamp for expiry, or the 'infinity' string

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::endAtomic ( $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 Also: IDatabase::startAtomic

Parameters

string $fname

Exceptions

DBError

Implemented in DatabaseBase, and DBConnRef.

Referenced by JobQueueDB\doBatchPushInternal().

IDatabase::estimateRowCount	(	$table,
		$vars = `'*'`,
		$conds = `''`,
		$fname = `__METHOD__`,
		$options = `[]`
	)

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 IDatabase::select().

Parameters

string	$table	Table name
string	$vars	Unused
array \| string	$conds	Filters on the table
string	$fname	Function name for profiling
array	$options	Options for select

Returns: int Row count

Implemented in DatabaseBase, DatabasePostgres, DatabaseMssql, DatabaseMysqlBase, and DBConnRef.

IDatabase::fetchObject ( $res )

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.

Parameters

ResultWrapper | stdClass $res Object as returned from IDatabase::query(), etc.

Returns: stdClass|bool

Exceptions

DBUnexpectedError Thrown if the database returns an error

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMssql, DatabaseMysqlBase, DBConnRef, DatabaseTestHelper, and FakeDatabase.

Referenced by DatabaseBase\selectRow(), and DatabaseBase\textFieldSize().

IDatabase::fetchRow ( $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.

Parameters

ResultWrapper $res Result object as returned from IDatabase::query(), etc.

Returns: array|bool

Exceptions

DBUnexpectedError Thrown if the database returns an error

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, DatabaseTestHelper, and FakeDatabase.

Referenced by DatabaseBase\estimateRowCount(), DatabaseBase\selectField(), and DatabaseBase\selectRowCount().

IDatabase::fieldExists	(	$table,
		$field,
		$fname = `__METHOD__`
	)

Determines whether a field exists in a table.

Parameters

string	$table	Table name
string	$field	Filed to check on that table
string	$fname	Calling function name (optional)

Returns: bool Whether $table has filed $field

Implemented in DatabaseBase, DatabaseMssql, and DBConnRef.

IDatabase::fieldInfo	(	$table,
		$field
	)

mysql_fetch_field() wrapper Returns false if the field doesn't exist

Parameters

string	$table	Table name
string	$field	Field name

Returns: Field

Implemented in DatabasePostgres, DatabaseOracle, DatabaseMssql, DatabaseSqlite, DatabaseMysqlBase, DBConnRef, FakeDatabase, and DatabaseTestHelper.

Referenced by DatabaseBase\fieldExists().

IDatabase::fieldName	(	$res,
		$n
	)

Get a field name in a result object.

See Also: http://www.php.net/mysql_field_name

Parameters

mixed	$res	A SQL result
int	$n

Returns: string

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, FakeDatabase, and DatabaseTestHelper.

IDatabase::freeResult ( $res )

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.

Parameters

mixed $res A SQL result

Implemented in DatabaseBase, DatabaseOracle, DatabasePostgres, DatabaseSqlite, DatabaseMssql, DatabaseMysqlBase, and DBConnRef.

IDatabase::getDBname ( )

Get the current DB name.

Returns: string

Implemented in DatabaseBase, DatabaseOracle, DatabasePostgres, and DBConnRef.

IDatabase::getFlag ( $flag )

Returns a boolean whether the flag $flag is set for this connection.

Parameters

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

Returns: bool

Implemented in DatabaseBase, and DBConnRef.

IDatabase::getInfinity ( )

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.

Returns: string

Implemented in DatabaseBase, DatabaseOracle, and DBConnRef.

IDatabase::getLag ( )

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.

Returns: int|bool Database replication lag in seconds or false on error

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

Referenced by LoadBalancer\safeGetLag().

IDatabase::getLBInfo ( $name = null )

Get properties passed down from the server info array of the load balancer.

Parameters

string $name The entry of the info array to get, or null to get the whole array

Returns: array|mixed|null

Implemented in DatabaseBase, and DBConnRef.

Referenced by LoadBalancer\safeWaitForMasterPos().

IDatabase::getMasterPos ( )

Get the position of this master.

Returns: DBMasterPos|bool False if this is not a master

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::getProperty ( $name )

General read-only accessor.

Parameters

string $name

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::getScopedLockAndFlush	(	$lockKey,
		$fname,
		$timeout
	)

Acquire a named lock, flush any transaction, and return an RAII style unlocker object.

This is suitiable for transactions that need to be serialized using cooperative locks, where each transaction can see each others' changes. Any transaction is flushed to clear out stale REPEATABLE-READ snapshot data. Once the returned object falls out of PHP scope, any transaction will be committed and the lock will be released.

If the lock acquisition failed, then no transaction flush happens, and null is returned.

Parameters

string	$lockKey	Name of lock to release
string	$fname	Name of the calling method
int	$timeout	Acquisition timeout in seconds

Returns: ScopedCallback|null

Exceptions

DBUnexpectedError

Since: 1.27

Implemented in DatabaseBase, and DBConnRef.

Referenced by LinksUpdate\acquirePageLock().

IDatabase::getServer ( )

Get the server hostname or IP address.

Returns: string

Implemented in DatabaseBase, DatabaseOracle, DatabasePostgres, and DBConnRef.

IDatabase::getServerInfo ( )

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.

Returns: string Version information from the database server

Implemented in DatabaseSqlite, DatabaseBase, DatabaseTestHelper, and DBConnRef.

IDatabase::getServerUptime ( )

Determines how long the server has been up STUB.

Returns: int

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::getServerVersion ( )

A string describing the current software version, like from mysql_get_server_info().

Returns: string Version information from the database server.

Implemented in DatabasePostgres, DatabaseOracle, DatabaseMssql, DatabaseMysqlBase, DatabaseSqlite, FakeDatabase, DBConnRef, DatabaseTestHelper, and FakeDatabaseMysqlBase.

Referenced by DatabaseBase\getServerInfo().

IDatabase::getSessionLagStatus ( )

Get the slave lag when the current transaction started or a general lag estimate if not transaction is active.

This is useful when transactions might use snapshot isolation (e.g. REPEATABLE-READ in innodb), so the "real" lag of that data is this lag plus transaction duration. If they don't, it is still safe to be pessimistic. In AUTO-COMMIT mode, this still gives an indication of the staleness of subsequent reads.

Returns: array ('lag': seconds or false on error, 'since': UNIX timestamp of BEGIN)

Since: 1.27

Implemented in DatabaseBase, and DBConnRef.

IDatabase::getSlavePos ( )

Get the replication position of this slave.

Returns: DBMasterPos|bool False if this is not a slave.

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::getSoftwareLink ( )

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.

Returns: string Wikitext of a link to the server software's web site

Implemented in DatabasePostgres, DatabaseOracle, DatabaseMssql, DatabaseMysqlBase, DatabaseSqlite, FakeDatabase, DBConnRef, and DatabaseTestHelper.

IDatabase::getType ( )

Get the type of the DBMS, as it appears in $wgDBtype.

Returns: string

Implemented in DatabaseMssql, DatabaseOracle, DatabasePostgres, DBConnRef, DatabaseSqlite, DatabaseTestHelper, DatabaseMysqlBase, and FakeDatabase.

Referenced by DatabaseBase\getSqlFilePath(), WatchedItemQueryService\getWatchedItemsWithRCInfoQueryConds(), MediaWikiTestCase\listTables(), DatabaseUpdater\newForDB(), DatabaseBase\patchPath(), MediaWikiTestCase\resetDB(), MediaWikiTestCase\setupDatabaseWithTestPrefix(), and MediaWikiTestCase\setupTestDB().

IDatabase::getWikiID ( )

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::implicitGroupby ( )

Returns true if this database does an implicit sort when doing GROUP BY.

Returns: bool

Implemented in DatabaseBase, DatabaseOracle, DatabasePostgres, DatabaseSqlite, DBConnRef, and DatabaseMssql.

IDatabase::implicitOrderby ( )

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.

Returns: bool

Implemented in DatabaseBase, DatabaseOracle, DatabasePostgres, DBConnRef, and DatabaseMssql.

IDatabase::indexExists	(	$table,
		$index,
		$fname = `__METHOD__`
	)

Determines whether an index exists Usually throws a DBQueryError on failure If errors are explicitly ignored, returns NULL on failure.

Parameters

string	$table
string	$index
string	$fname

Returns: bool|null

Implemented in DatabaseBase, DatabaseOracle, and DBConnRef.

IDatabase::indexUnique	(	$table,
		$index
	)

Determines if a given index is unique.

Parameters

string	$table
string	$index

Returns: bool

Implemented in DatabaseBase, and DBConnRef.

IDatabase::insert	(	$table,
		$a,
		$fname = `__METHOD__`,
		$options = `[]`
	)

INSERT wrapper, inserts an array into a table.

$a may be either:

A single associative array. The array keys are the field names, and the values are the values to insert. The values are treated as data and will be quoted appropriately. If NULL is inserted, this will be converted to a database NULL.
An array with numeric keys, holding a list of associative arrays. This causes a multi-row INSERT on DBMSs that support it. The keys in each subarray must be identical to each other, and in the same order.

Usually throws a DBQueryError on failure. If errors are explicitly ignored, returns success.

$options is an array of options, with boolean options encoded as values with numeric keys, in the same style as $options in IDatabase::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 IDatabase::affectedRows().

Parameters

string	$table	Table name. This will be passed through DatabaseBase::tableName().
array	$a	Array of rows to insert
string	$fname	Calling function name (use METHOD) for logs/profiling
array	$options	Array of options

Returns: bool

Implemented in DatabaseBase, DatabasePostgres, DatabaseSqlite, DatabaseMssql, DatabaseOracle, DBConnRef, and FakeDatabase.

Referenced by JobQueueDB\doBatchPushInternal(), DBFileJournal\doLogChangeBatch(), and QueryPage\recache().

IDatabase::insertId ( )

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();

Returns: int

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMssql, DBConnRef, DatabaseMysqli, FakeDatabase, DatabaseMysql, DatabaseTestHelper, and FakeDatabaseMysqlBase.

IDatabase::insertSelect	(	$destTable,
		$srcTable,
		$varMap,
		$conds,
		$fname = `__METHOD__`,
		$insertOptions = `[]`,
		$selectOptions = `[]`
	)

INSERT SELECT wrapper.

Takes data from a SELECT query and inserts it into another table.

Parameters

string	$destTable	The table name to insert into
string \| array	$srcTable	May be either a table name, or an array of table names to include in a join.
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 IDatabase::addQuotes()
array	$conds	Condition array. See $conds in IDatabase::select() for the details of the format of condition arrays. May be "*" to copy the whole table.
string	$fname	The function name of the caller, from METHOD
array	$insertOptions	Options for the INSERT part of the query, see IDatabase::insert() for details.
array	$selectOptions	Options for the SELECT part of the query, see IDatabase::select() for details.

Returns: ResultWrapper

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, DatabaseMssql, and DBConnRef.

IDatabase::isOpen ( )

Is a connection to the database open?

Returns: bool

Implemented in DatabaseBase, DatabaseTestHelper, and DBConnRef.

IDatabase::isReadOnly ( )

Returns: bool Whether this DB is read-only

Since: 1.27

Implemented in DatabaseBase, and DBConnRef.

IDatabase::lastDoneWrites ( )

Returns the last time the connection may have been used for write queries.

Should return a timestamp if unsure.

Returns: int|float UNIX timestamp or false

Since: 1.24

Implemented in DatabaseBase, and DBConnRef.

IDatabase::lastErrno ( )

Get the last error number.

See Also: http://www.php.net/mysql_errno

Returns: int

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMssql, DBConnRef, DatabaseMysqli, FakeDatabase, DatabaseMysql, DatabaseTestHelper, and FakeDatabaseMysqlBase.

Referenced by DatabaseMysqlBase\fetchObject(), DatabaseMysqlBase\fetchRow(), DatabaseBase\query(), DatabaseMysqlBase\wasDeadlock(), DatabaseMysqlBase\wasErrorReissuable(), DatabaseMysqlBase\wasLockTimeout(), and DatabaseMysqlBase\wasReadOnlyError().

IDatabase::lastError ( )

Get a description of the last error.

See Also: http://www.php.net/mysql_error

Returns: string

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, FakeDatabase, and DatabaseTestHelper.

Referenced by MediaWikiTestCase\assertSelect(), DatabaseBase\query(), DatabaseBase\reportConnectionError(), and DatabaseBase\sourceStream().

IDatabase::lastQuery ( )

Return the last query that went through IDatabase::query()

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::listTables	(	$prefix = `null`,
		$fname = `__METHOD__`
	)

List all tables on the database.

Parameters

string	$prefix	Only show tables with this prefix, e.g. mw_
string	$fname	Calling function name

Exceptions

MWException

Returns: array

Implemented in DatabaseBase, DatabaseMysqlBase, DatabasePostgres, DatabaseSqlite, DatabaseOracle, and DBConnRef.

IDatabase::lock	(	$lockName,
		$method,
		$timeout = `5`
	)

Acquire a named lock.

Named locks are not related to transactions

Parameters

string	$lockName	Name of lock to aquire
string	$method	Name of the calling method
int	$timeout	Acquisition timeout in seconds

Returns: bool

Implemented in DatabaseBase, DatabasePostgres, DatabaseMysqlBase, DatabaseSqlite, and DBConnRef.

IDatabase::lockIsFree	(	$lockName,
		$method
	)

Check to see if a named lock is available (non-blocking)

Parameters

string	$lockName	Name of lock to poll
string	$method	Name of method calling us

Returns: bool

Since: 1.20

Implemented in DatabaseBase, DatabasePostgres, DatabaseMysqlBase, and DBConnRef.

IDatabase::makeList	(	$a,
		$mode = `LIST_COMMA`
	)

Makes an encoded list of strings from an array.

Parameters

array	$a	Containing the data
int	$mode	Constant LIST_COMMA: Comma separated, no field names LIST_AND: ANDed WHERE clause (without the WHERE). See the documentation for $conds in IDatabase::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

Exceptions

MWException|DBUnexpectedError

Returns: string

Implemented in DatabaseBase, and DBConnRef.

Referenced by WatchedItemStore\getVisitingWatchersCondition().

IDatabase::makeWhereFrom2d	(	$data,
		$baseKey,
		$subKey
	)

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.

Parameters

array	$data	Organized as 2-d array(baseKeyVal => array(subKeyVal => [ignored], ...), ...)
string	$baseKey	Field name to match the base-level keys to (eg 'pl_namespace')
string	$subKey	Field name to match the sub-level keys to (eg 'pl_title')

Returns: string|bool SQL fragment, or false if no items in array

Implemented in DatabaseBase, and DBConnRef.

IDatabase::masterPosWait	(	DBMasterPos	$pos,
			$timeout
	)

Wait for the slave to catch up to a given master position.

Parameters

DBMasterPos	$pos
int	$timeout	The maximum number of seconds to wait for synchronisation

Returns: int|null Zero if the slave was past that position already, greater than zero if we waited for some period of time, less than zero if it timed out, and null on error

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

Referenced by LoadBalancer\safeWaitForMasterPos().

IDatabase::maxListLen ( )

Return the maximum number of items allowed in a list, or 0 for unlimited.

Returns: int

Implemented in DatabaseBase, and DBConnRef.

IDatabase::namedLocksEnqueue ( )

Check to see if a named lock used by lock() use blocking queues.

Returns: bool

Since: 1.26

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::nextSequenceValue ( $seqName )

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.

Parameters

string $seqName

Returns: null|int

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, and DBConnRef.

IDatabase::numFields ( $res )

Get the number of fields in a result object.

See Also: http://www.php.net/mysql_num_fields

Parameters

mixed $res A SQL result

Returns: int

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, DatabaseTestHelper, and FakeDatabase.

IDatabase::numRows ( $res )

Get the number of rows in a result object.

Parameters

mixed $res A SQL result

Returns: int

Implemented in DatabasePostgres, DatabaseOracle, DatabaseSqlite, DatabaseMysqlBase, DatabaseMssql, DBConnRef, DatabaseTestHelper, and FakeDatabase.

Referenced by DatabaseBase\selectField(), and DatabaseBase\selectRow().

IDatabase::onTransactionIdle ( callable $callback )

Run a callback 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.

Updates will execute in the order they were enqueued.

The callback takes one argument: How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_IDLE)

Parameters

callable $callback

Since: 1.20

Implemented in DatabaseBase, and DBConnRef.

IDatabase::onTransactionPreCommitOrIdle ( callable $callback )

Run a callback 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. If no transaction is active, then a transaction will wrap the callback.

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.

Updates will execute in the order they were enqueued.

Parameters

callable $callback

Since: 1.22

Implemented in DatabaseBase, and DBConnRef.

Referenced by SqlDataUpdate\invalidatePages().

IDatabase::onTransactionResolution ( callable $callback )

Run a callback as soon as the current transaction commits or rolls back.

An error is thrown if no transaction is pending. 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 combining cooperative locks and DB transactions.

The callback takes one argument: How the transaction ended (IDatabase::TRIGGER_COMMIT or IDatabase::TRIGGER_ROLLBACK)

Parameters

callable $callback

Returns: mixed

Since: 1.28

Implemented in DatabaseBase, and DBConnRef.

IDatabase::open	(	$server,
		$user,
		$password,
		$dbName
	)

Open a connection to the database.

Usually aborts on failure

Parameters

string	$server	Database server host
string	$user	Database user name
string	$password	Database user password
string	$dbName	Database name

Returns: bool

Exceptions

DBConnectionError

Implemented in DatabaseOracle, DatabasePostgres, DatabaseSqlite, DBConnRef, DatabaseTestHelper, DatabaseMssql, DatabaseMysqlBase, and FakeDatabase.

Referenced by DatabaseBase\__construct().

IDatabase::pendingWriteCallers ( )

Get the list of method names that did write queries for this transaction.

Returns: array

Since: 1.27

Implemented in DatabaseBase, and DBConnRef.

IDatabase::pendingWriteQueryDuration ( )

Get the time spend running write queries for this transaction.

High times could be due to scanning, updates, locking, and such

Returns: float|bool Returns false if not transaction is active

Since: 1.26

Implemented in DatabaseBase, and DBConnRef.

IDatabase::ping ( )

Ping the server and try to reconnect if it there is no connection.

Returns: bool Success or failure

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::query	(	$sql,
		$fname = `__METHOD__`,
		$tempIgnore = `false`
	)

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.

Parameters

string	$sql	SQL query
string	$fname	Name of the calling function, for profiling/SHOW PROCESSLIST comment (you can use METHOD or add some extra info)
bool	$tempIgnore	Whether to avoid throwing an exception on errors... maybe best to catch the exception instead?

Exceptions

MWException

Returns: bool|ResultWrapper True for a successful write query, ResultWrapper object for a successful read query, or false on failure if $tempIgnore set

Implemented in DatabaseBase, DBConnRef, DatabaseTestHelper, and DatabaseSqliteMock.

Referenced by JobRunner\commitMasterChanges(), and MySqlLockManager\initConnection().

IDatabase::replace	(	$table,
		$uniqueIndexes,
		$rows,
		$fname = `__METHOD__`
	)

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.

Parameters

string	$table	The table to replace the row(s) in.
array	$uniqueIndexes	Is an array of indexes. Each element may be either a field name or an array of field names
array	$rows	Can be either a single row to insert, or multiple rows, in the same format as for IDatabase::insert()
string	$fname	Calling function name (use METHOD) for logs/profiling

Implemented in DatabaseBase, DatabaseSqlite, DatabaseMysqlBase, and DBConnRef.

IDatabase::reportConnectionError ( $error = 'Unknown error' )

Parameters

string $error Fallback error message, used if none is given by DB

Exceptions

DBConnectionError

Implemented in DatabaseBase, and DBConnRef.

IDatabase::reportQueryError	(	$error,
		$errno,
		$sql,
		$fname,
		$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.

Parameters

string	$error
int	$errno
string	$sql
string	$fname
bool	$tempIgnore

Exceptions

DBQueryError

Implemented in DatabaseBase, DatabasePostgres, and DBConnRef.

IDatabase::rollback	(	$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.

Parameters

string	$fname
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.

Exceptions

DBUnexpectedError

Since: 1.23 Added $flush parameter

Implemented in DatabaseBase, and DBConnRef.

Referenced by JobQueueDB\doBatchPushInternal(), and Maintenance\rollbackTransaction().

IDatabase::select	(	$table,
		$vars,
		$conds = `''`,
		$fname = `__METHOD__`,
		$options = `[]`,
		$join_conds = `[]`
	)

Execute a SELECT query constructed using the various parameters provided.

See below for full details of the parameters.

Parameters

string \| array	$table	Table name
string \| array	$vars	Field names
string \| array	$conds	Conditions
string	$fname	Caller function name
array	$options	Query options
array	$join_conds	Join conditions
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.

Do not use untrusted user input as a table name. Alias names should not have characters outside of the Basic multilingual plane.

Parameters

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.

Untrusted user input must not be passed to this parameter.

Parameters

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:

Untrusted user input is safe in the values of string keys, however untrusted input must not be used in the array key names or in the values of numeric keys. Escaping of untrusted input used in values of numeric keys should be done via IDatabase::addQuotes()

Parameters

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

Parameters

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 the same as the $conds parameter. Thus it can be an SQL fragment, or an array where the string keys are equality and the numeric keys are SQL fragments all AND'd together. For example:

array( 'page' => array( 'LEFT JOIN', 'page_latest=rev_id' ) )

Returns: 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.

Implemented in DatabaseBase, DatabaseMssql, and DBConnRef.

Referenced by JobQueueDB\doBatchPushInternal(), DBFileJournal\doGetChangeEntries(), and SpecialWhatLinksHere\showIndirectLinks().

IDatabase::selectDB ( $db )

Change the current database.

Parameters

string $db

Returns: bool Success or failure

Implemented in DatabaseBase, DatabaseOracle, DatabaseMssql, DatabasePostgres, DBConnRef, DatabaseMysqli, and DatabaseMysql.

IDatabase::selectField	(	$table,
		$var,
		$cond = `''`,
		$fname = `__METHOD__`,
		$options = `[]`
	)

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.

Parameters

string \| array	$table	Table name. See IDatabase::select() for details.
string	$var	The field name to select. This must be a valid SQL fragment: do not use unvalidated user input.
string \| array	$cond	The condition array. See IDatabase::select() for details.
string	$fname	The function name of the caller.
string \| array	$options	The query options. See IDatabase::select() for details.

Returns: bool|mixed The value from the field, or false on failure.

Implemented in DatabaseBase, and DBConnRef.

Referenced by DBFileJournal\doGetCurrentPosition(), and DBFileJournal\doGetPositionAtTime().

IDatabase::selectFieldValues	(	$table,
		$var,
		$cond = `''`,
		$fname = `__METHOD__`,
		$options = `[]`
	)

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.

Parameters

string \| array	$table	Table name. See IDatabase::select() for details.
string	$var	The field name to select. This must be a valid SQL fragment: do not use unvalidated user input.
string \| array	$cond	The condition array. See IDatabase::select() for details.
string	$fname	The function name of the caller.
string \| array	$options	The query options. See IDatabase::select() for details.

Returns: bool|array The values from the field, or false on failure

Since: 1.25

Implemented in DBConnRef.

Referenced by Title\purgeExpiredRestrictions().

IDatabase::selectRow	(	$table,
		$vars,
		$conds,
		$fname = `__METHOD__`,
		$options = `[]`,
		$join_conds = `[]`
	)

Single row SELECT wrapper.

Equivalent to IDatabase::select(), except that a single row object is returned. If the query returns no rows, false is returned.

Parameters

string \| array	$table	Table name
string \| array	$vars	Field names
array	$conds	Conditions
string	$fname	Caller function name
string \| array	$options	Query options
array \| string	$join_conds	Join conditions

Returns: stdClass|bool

Implemented in DatabaseOracle, DatabaseBase, and DBConnRef.

IDatabase::selectRowCount	(	$tables,
		$vars = `'*'`,
		$conds = `''`,
		$fname = `__METHOD__`,
		$options = `[]`,
		$join_conds = `[]`
	)

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 IDatabase::select().

Since: 1.27 Added $join_conds parameter

Parameters

array \| string	$tables	Table names
string	$vars	Unused
array \| string	$conds	Filters on the table
string	$fname	Function name for profiling
array	$options	Options for select
array	$join_conds	Join conditions (since 1.27)

Returns: int Row count

Implemented in DatabaseBase, and DBConnRef.

IDatabase::selectSQLText	(	$table,
		$vars,
		$conds = `''`,
		$fname = `__METHOD__`,
		$options = `[]`,
		$join_conds = `[]`
	)

The equivalent of IDatabase::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().

Parameters

string \| array	$table	Table name
string \| array	$vars	Field names
string \| array	$conds	Conditions
string	$fname	Caller function name
string \| array	$options	Query options
string \| array	$join_conds	Join conditions

Returns: string SQL query string.

See Also: IDatabase::select()

Implemented in DatabaseBase, DatabasePostgres, DatabaseMssql, and DBConnRef.

Referenced by SpecialWhatLinksHere\showIndirectLinks().

IDatabase::serverIsReadOnly ( )

Returns: bool Whether the DB is marked as read-only server-side

Since: 1.28

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::setBigSelects ( $value = true )

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.

Parameters

bool | string $value True for allow, false for deny, or "default" to restore the initial value

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::setFlag ( $flag )

Set a flag for this connection.

Parameters

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

Implemented in DatabaseBase, DBConnRef, and FakeDatabase.

IDatabase::setLBInfo	(	$name,
		$value = `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.

Parameters

string	$name
array	$value

Implemented in DatabaseBase, and DBConnRef.

IDatabase::setSchemaVars ( $vars )

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.

Parameters

bool | array $vars Mapping variable name to value.

Implemented in DatabaseBase, and DBConnRef.

IDatabase::setSessionOptions ( array $options )

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.

Parameters

array $options

Returns: void

Implemented in DatabaseBase, DatabaseMysqlBase, and DBConnRef.

IDatabase::startAtomic ( $fname = __METHOD__ )

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 IDatabase::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

Parameters

string $fname

Exceptions

DBError

Implemented in DatabaseBase, and DBConnRef.

Referenced by JobQueueDB\doBatchPushInternal().

IDatabase::strreplace	(	$orig,
		$old,
		$new
	)

Returns a comand for str_replace function in SQL query.

Uses REPLACE() in MySQL

Parameters

string	$orig	Column to modify
string	$old	Column to seek
string	$new	Column to replace with

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::tableExists	(	$table,
		$fname = `__METHOD__`
	)

Query whether a given table exists.

Parameters

string	$table
string	$fname

Returns: bool

Implemented in DatabaseBase, DatabaseOracle, DatabaseMssql, DBConnRef, and DatabaseTestHelper.

IDatabase::tablePrefix ( $prefix = null )

Get/set the table prefix.

Parameters

string $prefix The table prefix to set, or omitted to leave it unchanged.

Returns: string The previous table prefix.

Implemented in DatabaseBase, and DBConnRef.

IDatabase::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.

The result is unquoted, and needs to be passed through addQuotes() before it can be included in raw SQL.

Parameters

string | int $ts

Returns: string

Implemented in DatabaseBase, DatabasePostgres, DatabaseOracle, and DBConnRef.

Referenced by DBFileJournal\doGetPositionAtTime(), DBFileJournal\doLogChangeBatch(), DBFileJournal\doPurgeOldLogs(), WatchedItemStore\getVisitingWatchersCondition(), Title\invalidateCache(), Block\purgeExpired(), Title\purgeExpiredRestrictions(), and QueryPage\recache().

IDatabase::timestampOrNull ( $ts = null )

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.

Parameters

string | int $ts

Returns: string

Implemented in DatabaseBase, and DBConnRef.

IDatabase::trxLevel ( )

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.

Returns: int The previous value

Implemented in DatabaseBase, and DBConnRef.

IDatabase::trxTimestamp ( )

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.

Returns: float|null Returns null if there is not active transaction

Since: 1.25

Implemented in DatabaseBase, and DBConnRef.

IDatabase::unionQueries	(	$sqls,
		$all
	)

Construct a UNION query This is used for providing overload point for other DB abstractions not compatible with the MySQL syntax.

Parameters

array	$sqls	SQL statements to combine
bool	$all	Use UNION ALL

Returns: string SQL fragment

Implemented in DatabaseBase, DatabaseOracle, DatabaseSqlite, and DBConnRef.

IDatabase::unionSupportsOrderAndLimit ( )

Returns true if current database backend supports ORDER BY or LIMIT for separate subqueries within the UNION construct.

Returns: bool

Implemented in DatabaseBase, DatabaseSqlite, DBConnRef, and DatabaseMssql.

IDatabase::unlock	(	$lockName,
		$method
	)

Release a lock.

Named locks are not related to transactions

Parameters

string	$lockName	Name of lock to release
string	$method	Name of the calling method

Returns: 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

Implemented in DatabaseBase, DatabasePostgres, DatabaseMysqlBase, DatabaseSqlite, and DBConnRef.

IDatabase::update	(	$table,
		$values,
		$conds,
		$fname = `__METHOD__`,
		$options = `[]`
	)

UPDATE wrapper.

Takes a condition array and a SET array.

Parameters

string	$table	Name of the table to UPDATE. This will be passed through DatabaseBase::tableName().
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 IDatabase::addQuotes().
array	$conds	An array of conditions (WHERE). See IDatabase::select() for the details of the format of condition arrays. Use '*' to update all rows.
string	$fname	The function name of the caller (from METHOD), for logging and profiling.
array	$options	An array of UPDATE options, can be: IGNORE: Ignore unique key conflicts LOW_PRIORITY: MySQL-specific, see MySQL manual.

Returns: bool

Implemented in DatabaseBase, DatabaseOracle, DatabaseMssql, and DBConnRef.

Referenced by Title\invalidateCache().

IDatabase::upsert	(		$table,
		array	$rows,
		array	$uniqueIndexes,
		array	$set,
			$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

Parameters

string	$table	Table name. This will be passed through DatabaseBase::tableName().
array	$rows	A single row or list of rows to insert
array	$uniqueIndexes	List of single field names or field name tuples
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 IDatabase::addQuotes().
string	$fname	Calling function name (use METHOD) for logs/profiling