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

|Evaluates the supplied {{Code|$query}} string as XQuery expression and returns the resulting items.<br/>The evaluated If the query has its own query context. If a returned node is stored in a databaseof type {{Code|xs:anyURI}}, the module located at this URI will be retrieved (a main-memory copy relative URI will be returned as resultresolved against the static base URI). Otherwise, because the referenced database input is closed after query execution and will not expected to be accessible anymoreof type {{Code|xs:string}}.<br />Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings:

* {{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 Overwrites the base URI of the query; will be used when resolving relative URIs by functions such as {{Code|fn:doc}}. Added with * {{VersionCode|8pass}}: passes on the original error info (line and column number, optional file uri).5By 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 limit.<br/>{{Error|BXXQ0005nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.

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==xquery:eval-update==

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

|Evaluates {{Code|$a query}} as updating XQuery expression at runtime.<br/>All updates will be added to the [[XQuery Update#Pending Update List|Pending Update List]] of the main query and performed after the evaluation of the main query.<br />The rules of the {{Code|$bindings}} and {{Code|$options}} parameters for all arguments 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 limit.<br/>{{Error|BXXQ0005nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query.|-| '''Examples'''|* Removes entries from a temporary databases and returns an info string:<syntaxhighlight lang="xquery">xquery:eval-update(" delete node db:open('tmp')/*, update:output('TEMPORARY DATABASE WAS CLEANED UP')")</syntaxhighlight>

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

* {{Code|pass}}: passes on by default, the original option is {{Code|false}}. If an error info (is raised, the line and /column number, and the optional file uri)will refer to the location of the function call. By default, this  If the option is enabled, the line/column and file uri will be adopted from the raised error.* {{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|falsefn:doc}}.

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

==xquery:invoke=Parallelized Execution=

{{Mark|Updated with Version 8.5}}: Relative URIs will always Parallel query execution is recommendable if you have various calls that require a lot of time, but that cannot be resolved against sped up by rewriting the static base URI of code. This is e. g. the querycase if external URLs are called. {| width='100%'|-| width='120' | '''Signatures'''|{{Func|xquery:invoke|$uri If you are parallelizing local data reads (such as xs:string|item(the access to a database)*}}<br />{{Func|xquery:invoke|$uri as xs:string, $bindings as map(*)|item()*}}<br />{{Func|xquery:invoke|$uri as xs:stringsingle-threaded queries will usually be faster, $bindings as map(*)because parallelized access to disk data often results in randomized access patterns, $options as map(*)|item()*}}<br />|-| '''Summary'''|Evaluates the XQuery module located at {{Code|$uri}} at runtime and returns the resulting items. A relative URI which will rarely be resolved against optimized by the static base URI caching strategies of HDDs, SSDs, or the query.<br />The rules of the {{Code|$bindings}} and {{Code|$options}} parameters are the same as for [[#xquery:eval|xquery:eval]].|-| '''Errors'''|{{Error|BXXQ0001|#Errors}} the expression contains [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|BXXQ0003|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|BXXQ0004|#Errors}} query execution exceeded timeout.<br/>{{Error|BXXQ0005|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the queryoperating system.|}

|This function executes the supplied (non-updating) functions in parallel.<br/>Parallel query execution is recommendable if you have various calls that require a lot of time, but 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 accessing a database), your single-threaded query will usually be faster, because parallelized access to disk data will often lead to randomized access patterns, which can hardly be optimized by your HD or SSD.

<pre classsyntaxhighlight lang='brush"xquery">let $f := function() { prof:sleep(1000) }return xquery:fork-join(($f, $f))</syntaxhighlight>* In the following query, up to four URLs will be requested in parallel:<syntaxhighlight lang="xquery'">

let $url := 'http://url.com/path/' || $segment

return xquery:fork-join($funcs)</presyntaxhighlight>

|{{Error|unexpectederror|#Errors}} an unexpected error occurred while running a query or function in a separate thread.

|{{Code|BXXQ0001permission}}|The specified Insufficient permissions for evaluating the query contains [[XQuery Update#Updating Expressions|updating expressions]].

|{{Code|BXXQ0002update}}|The specified query contains no [[XQuery Update#Updating Expressions|updating expressionsexpression]]found or expected.

|{{Code|BXXQ0003timeout}}|Insufficient permissions for evaluating the queryQuery execution exceeded timeout.

|{{Code|BXXQ0004memory}}|Query execution exceeded timeout or memory limit.

|{{Code|BXXQ0005nested}}

* Deleted: xquery:type (moved to [[Profiling Module]])

 * Added: [[#xquery:update|xquery:update]], [[#xquery:parse|xquery:parse]]* Deleted: [[#xquery:evaluate|xquery:evaluate]] (opened databases will now be closed by main query)