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==Process Locking==
In order to enable locking on global (process) level, the option <code>[[Options#GLOBALLOCK|GLOBALLOCK]]</code> can be set to {{Code|true}}. This can e.g. be done by editing your {{Code|.basex}} file (see [[Options]] for more details). If process locking is active, a process that performs write operations will queue all other operations.
→Concurrency Control
* Subsequent operations (read or write) will be queued until the updating transaction has completed.
Each database has its own queue: An update on database A will not block operations on database B. This is under the premise that it can be statically determined, i.e., before the transaction is evaluated) , which databases will be accessed by a transaction (see [[#Limitations|below]]). The number of maximum parallel transactions can be adjusted with the [[Options#PARALLEL|PARALLEL]] option. With {{Version|8.6}}, locking has been improved: * Jobs without database access will never be locked. Globally locking jobs can now be executed in parallel with non-locking jobs.* A {{Option|FAIRLOCK}} option has been added: By default, read transactions will now be favored, and transactions that access no databases can be evaluated even if the transactions limit has been reached.
==External Side Effects==
You can consult the query info output (which you find in the [[GUI#Visualizations|Info View]] of the GUI or which you can turn on by setting <code>[[Options#QUERYINFO|QUERYINFO]]</code> to {{Code|true}}) to find out which databases have been locked by a query.
=File-System Locks=
=Changelog=
;Version 8.6
* Updated: New {{Option|FAIRLOCK}} option, improved detection of lock patterns.
;Version 7.8
* Added: Locks can also be acquired on [[Java Bindings#Locking|Java functions]].
;Version 7.6
* Added: database locking introduced, replacing process locking.
;Version 7.2.1
* Updated: pin files replaced with shared/exclusive filesystem locking.
;Version 7.2
* Added: pin files to mark open databases.
;Version 7.1
* Added: update lock files.
