MYSQLND_MS_XA_GC(3)							 1						       MYSQLND_MS_XA_GC(3)

mysqlnd_ms_xa_gc - Garbage collects unfinished XA transactions after severe errors

SYNOPSIS

       int mysqlnd_ms_xa_gc (mixed  $connection, [string  $gtrid], [boolean  $ignore_max_retries])

DESCRIPTION

	Garbage collects unfinished XA transactions.

	The XA protocol is a blocking protocol. There exist cases when servers participating in a global transaction cannot make progress when the
       transaction coordinator crashes or disconnects. In such a case, the MySQL servers keep waiting for instructions to finish the  XA  transac-
       tion in question. Because transactions occupy resources, transactions should always be terminated properly.

	Garbage  collection requires configuring a state store to track global transactions. Should a PHP client crash in the middle of a transac-
       tion and a new PHP client be started, then the built-in garbage collection can learn about the aborted global transaction and terminate it.
       If you do not configure a state store, the garbage collection cannot perform any cleanup tasks.

	The  state  store  should  be  crash-safe  and be highly available to survive its own crash. Currently, only MySQL is supported as a state
       store.

	Garbage collection can also be performed automatically in the background. See the plugin configuration	directive  garbage_collection  for
       details.

       Note

	      Experimental

	       The feature is currently under development. There may be issues and/or feature limitations. Do not use in production environments.

PARAMETERS

	      o $connection
		- A MySQL connection handle obtained from any of the connect functions of the mysqli, mysql or PDO_MYSQL extensions.

	      o $gtrid
		-  Global  transaction	identifier  (gtrid). If given, the garbage collection considers the transaction only. Otherwise, the state
		store is scanned for any unfinished transaction.

	      o $ignore_max_retries
		- Whether to ignore the plugin configuration max_retries setting. If garbage collection continuously  fails  and  the  max_retries
		limit  is  reached prior to finishing the failed global transaction, you can attempt further runs prior to investigating the cause
		and solving the issue manually by issuing appropriate SQL statements on the participants.  Setting  the  parameter  has  the  same
		effect as temporarily setting max_retries = 0.

RETURN VALUES

	Returns TRUE if garbage collection was successful. Otherwise, returns FALSE

SEE ALSO

       Quickstart XA/Distributed transactions, Runtime configuration, State store configuration, mysqlnd_ms_get_stats(3).

PHP Documentation Group 												       MYSQLND_MS_XA_GC(3)