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Various ways exist to access * The current value of an option can be requested with the {{Command|GET}} command. Local options can be changed via {{Command|SET}} (all global options, except for {{Option|DEBUG}}, can only be changed at startup time). If an option is of type ''boolean'', and change options:if no value is specified, its current value will be inverted.
* The current value of an option can be requested with the {{Command|GET}} command. Local options can be changed via {{Command|SET}} (all global options, except for {{Option|DEBUG}}, can only be changed at startup time). All values are ''static'': They stay valid until they are changed once again by another operation. If an option is of type ''boolean'', and if no value is specified, its current value will be inverted. * The {{Code|.basex}} [[Configuration#Configuration Files|configuration file]] is parsed by every new local BaseX instance. It contains all global options. Local options can be specified at the end of the file after the "{{Code|Local Options" }} comment:
→PARALLEL
The options listed on this page influence the way how database [[Commands|commands]] are executed and XQuery expressions are evaluated. Two kinds of options exist:
* '''[[#Global Options|Global Options]]''' are valid for all BaseX instances;in the same JVM. This is particularly relevant if you are working with the client/server architecture.
* '''Local options''' (all remaining ones) are specific to a client or session.
Values of options are either ''strings'', ''numbers'' or ''booleans''.Options are ''static'' and not bound to a single operation (for example, the next command). Various ways exist to access and change options:
<pre class="brush:perl">
|-
| '''Summary'''
|Denotes the maximum allowed number of parallel [[Transaction Management|transactions]]:* If {{Option|FAIRLOCK}} is enabled, the number of parallel transactions will never exceed the specified value.<br/>Note * If the option is disabled (which is the default), the limit only applies to transactions that a access databases.* The main reason for allowing parallel operations is to prevent slow transactions from blocking all other operations. A higher number of parallel operations may increase disk activity and thus slow down queries. In some cases, a single transaction may even give you better results than any parallel activity. The main reason for allowing parallel operations is to prevent slow transactions from blocking all other operations.
|}
|-
| '''Summary'''
|If this option is turned on, new databases will be exclusively created in main memory. :* Most queries will be evaluated faster in main -memory mode, but all data is lost if the BaseX instance in which the database was created is shut down. The value of this option * It is not possible to store binary resources in a main-memory database.* A main-memory database will be assigned once have no disk representation. However, it is possible to export the database via the {{Command|EXPORT}} command, and create a new databasefrom the exported file in a second step.* This option will not be available for [[Database Module#db:create|db:create]], and cannot because the database would not be changed accessible anymore after thatdatabase creation, i. e., outside the query scope.
|}
