Changes

This [[Module Library|XQuery Module]] contains functions for parsing and evaluating XQuery strings and modules at runtime, and to run code in parallel.

All functions and errors in this module are assigned to the <code><nowiki>http://basex.org/modules/xquery</nowiki></code> namespace, which is statically bound to the {{Code|xquery}} prefix.<br/>All errors are assigned to the <code><nowiki>http://basex.org/errors</nowiki></code> namespace, which is statically bound to the {{Code|bxerr}} prefix.

=FunctionsDynamic Evaluation=

|{{Func|xquery:eval|$query as xs:string|item()*}}<br />{{Func|xquery:eval|$query as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:eval|$query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|item()*}}<br />

* {{Code|memory}}: query execution will be interrupted if the specified number of megabytes will be exceeded. This check works best if only one process is running at the same time. Moreover, please note that this option enforces garbage collection, so it will take some additional time, and it requires GC to be enabled in your JVM.* {{Code|base-uri}}: set [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. This URI will be used when resolving relative URIs by functions such as {{Code|fn:doc}}.* {{Code|pass}}: passes on the original error info (line and column number, optional file uri). By default, this option is {{Code|false}}.

|{{Error|BXXQ0001update|#Errors}} the query contains [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|BXXQ0003permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|BXXQ0004timeout|#Errors}} query execution exceeded timeout or .<br/>{{Error|limit|#Errors}} query execution exceeded memory constraintslimit.<br/>{{Error|FOTY0013nested|#Errors}} the expression yields function itemsnested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.

==xquery:eval-update==

|{{Func|xquery:eval-update|$query as xs:string|item()*}}<br />{{Func|xquery:eval-update|$query as xs:string, $bindings as map(*)?|item()*}}<br />{{Func|xquery:eval-update|$query as xs:string, $bindings as map(*)?, $options as map(xs:string, xs:string*)?|item()}}<br />

|Evaluates {{Code|$query}} as updating XQuery expression at runtime.<br/>All updates will be added to the [[XQuery Update#Pending Update List|Pending Update List]] of the main query and performed after the evaluation of the main query.<br />The semantics rules of the {{Code|$bindings}} and {{Code|$options}} parameters is are the same as for [[#xquery:eval|xquery:eval]].

|{{Error|BXXQ0002update|#Errors}} the query contains no [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|BXXQ0003permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|BXXQ0004timeout|#Errors}} query execution exceeded timeout or .<br/>{{Error|limit|#Errors}} query execution exceeded memory constraintslimit.<br/>{{Error|FOTY0013nested|#Errors}} the expression yields function itemsnested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.

|{{Func|xquery:parse|$query as xs:string|item()*?}}<br />{{Func|xquery:parse|$query as xs:string, $options as map(*)?|item()?}}<br />

* {{Code|pass}}: pass passes on the original error info (line and column number, optional file uri). By default, this option is {{Code|false}}.* {{Code|base-uri}}: set [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. This URI will be used when resolving relative URIs by functions such as {{Code|fn:doc}}.

|{{Func|xquery:parse-uri|$uri as xs:string|item()*?}}<br />{{Func|xquery:parse-uri|$uri as xs:string, $options as map(*)?|item()*?}}<br />

|Parses the XQuery module located at {{Code|$uri}} and returns the resulting query plan. A relative URI will be resolved against the static base URI of the query. The rules for the {{Code|$options}} parameter is are the same as for [[#xquery:parse|xquery:parse]].

=Parallelized Execution=xquery:invoke== Parallel query execution is recommendable if you have various calls that require a lot of time, but that cannot be sped up by rewriting the code. This is e. g. the case if external URLs are called. If you are parallelizing local data reads (such as the access to a database), single-threaded queries will usually be faster, because parallelized access to disk data often results in randomized access patterns, which will rarely be optimized by the caching strategies of HDDs, SSDs, or the operating system.

{{Mark|Updated with Version 8.4}}: will be renamed to {{Code|==xquery:evalfork-uri}}join==

|{{Func|xquery:invokefork-join|$uri functions as xs:string|itemfunction()*}}<br />{{Func|xquery:invoke|$uri as xs:string, $bindings as map(*)|item()*}}<br />{{Func|xquery:invoke|$uri as xs:string, $bindings as map(*), $options as map(*)|item()*}}<br />

| '''Summary'''|Evaluates This function executes the XQuery module located at {{Code|$uri}} at runtime and returns the resulting items. Database nodes supplied (non-updating) functions in the result will be copied and returned instead.<br />The semantics of the {{Code|$bindings}} and {{Code|$options}} parameters is the same as for [[#xquery:eval|xquery:eval]]parallel.

| '''ErrorsExamples'''|{{Error|BXXQ0001|#Errors}} the expression contains [[XQuery Update#Updating Expressions|updating expressions]].* The following function sleeps in parallel; it will be finished in 1 second if your system has at least 2 cores:<br/pre class='brush:xquery'>let $f := function() {{Error|BXXQ0003|#Errorsprof:sleep(1000) }} insufficient permissions for evaluating the query.return xquery:fork-join(($f, $f))<br/pre>{{Error|BXXQ0004|#Errors}} * In the following query execution exceeded timeout., up to four URLs will be requested in parallel:<br/pre class='brush:xquery'>{{Error|FOTY0013|#Errors}} the expression yields function items.<br/>Any other error that may occur while evaluating the query.|} ==xquery:type==fork-join( for $segment in 1 to 4{| width let $url :='100%http://url.com/path/'|| $segment return function() { http:send-request((), $url) })</pre>

| width='120' | '''SignaturesErrors'''|{{Func|xquery:typeError|$expr as item()*|item()*}}|-| '''Summary'''|Similar to {{Codeerror|fn:trace($expr, $msg)#Errors}}, but instead of a user-defined message, it emits the compile-time type and estimated result size of its argumentan unexpected error occurred.

|{{Code|BXXQ0001permission}}|The specified Insufficient permissions for evaluating the query contains .|-|{{Code|update}}|[[XQuery Update#Updating Expressions|updating expressionsexpression]]found or expected.|-|{{Code|timeout}}|Query execution exceeded timeout.

|{{Code|BXXQ0002memory}}|The specified query contains no [[XQuery Update#Updating Expressions|updating expressions]]Query execution exceeded memory limit.

|{{Code|BXXQ0003nested}}|Insufficient permissions for evaluating the Nested queryevaluation is not allowed.

|{{Code|BXXQ0004error}}|Query execution exceeded timeoutAn unexpected error occurred.

 * Added: [[#xquery:update|xquery:update]], [[#xquery:parse|xquery:parse]]