Difference between revisions of "XQuery Module"
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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 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/> | ||
− | = | + | =Evaluation= |
==xquery:eval== | ==xquery:eval== | ||
+ | |||
+ | {{Announce|Updated with Version 11}}: The Clark notation was replaced with the [[XQuery 3.0#Expanded QNames|Expanded QNames]] notation. | ||
{| width='100%' | {| width='100%' | ||
− | |- | + | |- valign="top" |
− | | width='120' | ''' | + | | width='120' | '''Signature''' |
− | | | + | |<pre>xquery:eval( |
− | |- | + | $query as xs:anyAtomicType, |
+ | $bindings as map(*)? := map { }, | ||
+ | $options as map(*)? := map { } | ||
+ | ) as item()*</pre> | ||
+ | |- valign="top" | ||
| '''Summary''' | | '''Summary''' | ||
|Evaluates the supplied {{Code|$query}} and returns the resulting items. If the query is of type {{Code|xs:anyURI}}, the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type {{Code|xs:string}}. | |Evaluates the supplied {{Code|$query}} and returns the resulting items. If the query is of type {{Code|xs:anyURI}}, the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type {{Code|xs:string}}. | ||
Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings: | Variables and context items can be declared via {{Code|$bindings}}. The specified keys must be QNames or strings: | ||
* If a key is a QName, it will be directly adopted as variable name. | * If a key is a QName, it will be directly adopted as variable name. | ||
− | * It a key is a string, it may be prefixed with a dollar sign. Namespace can be specified using the [ | + | * It a key is a string, it may be prefixed with a dollar sign. Namespace can be specified using the [[XQuery 3.0#Expanded QNames|Expanded QNames]] notation. |
* If the specified string is empty, the value will be bound to the context item. | * If the specified string is empty, the value will be bound to the context item. | ||
The {{Code|$options}} parameter contains evaluation options: | The {{Code|$options}} parameter contains evaluation options: | ||
Line 26: | Line 32: | ||
* {{Code|base-uri}}: set [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. Overwrites the base URI of the query; will be used when resolving relative URIs by functions such as {{Code|fn:doc}}. | * {{Code|base-uri}}: set [https://www.w3.org/TR/xquery-31/#dt-static-base-uri base-uri property] for the query. Overwrites the base URI of the query; 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}}. | * {{Code|pass}}: passes on the original error info (line and column number, optional file uri). By default, this option is {{Code|false}}. | ||
− | |- | + | |- valign="top" |
| '''Errors''' | | '''Errors''' | ||
|{{Error|update|#Errors}} the query contains [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|limit|#Errors}} query execution exceeded memory limit.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query. | |{{Error|update|#Errors}} the query contains [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|limit|#Errors}} query execution exceeded memory limit.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query. | ||
− | |- | + | |- valign="top" |
| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * {{Code|xquery:eval("1+3")}} returns {{Code|4}}.<br /> | + | * {{Code|xquery:eval("1+3")}} returns {{Code|4}}.<br/> |
* If a URI is supplied, the query in the specified file will be evaluated: | * If a URI is supplied, the query in the specified file will be evaluated: | ||
− | < | + | <pre lang='xquery'> |
xquery:eval(xs:anyURI('cleanup.xq')) | xquery:eval(xs:anyURI('cleanup.xq')) | ||
− | </ | + | </pre> |
− | * You can bind the context and e.g. operate on a certain database only:<br /> | + | * You can bind the context and e.g. operate on a certain database only:<br/> |
− | < | + | <pre lang='xquery'> |
− | xquery:eval("//country", map { '': db: | + | xquery:eval("//country", map { '': db:get('factbook') }) |
− | </ | + | </pre> |
* The following expressions use strings as keys. All of them return 'XML':<br/> | * The following expressions use strings as keys. All of them return 'XML':<br/> | ||
− | < | + | <pre lang='xquery'> |
xquery:eval(".", map { '': 'XML' }), | xquery:eval(".", map { '': 'XML' }), | ||
Line 53: | Line 59: | ||
map { '{URI}xml': 'XML' } | map { '{URI}xml': 'XML' } | ||
) | ) | ||
− | </ | + | </pre> |
* The following expressions use QNames as keys. All of them return 'XML':<br/> | * The following expressions use QNames as keys. All of them return 'XML':<br/> | ||
− | < | + | <pre lang='xquery'> |
declare namespace pref = 'URI'; | declare namespace pref = 'URI'; | ||
Line 65: | Line 71: | ||
let $vars := map { xs:QName('pref:xml'): 'XML' } | let $vars := map { xs:QName('pref:xml'): 'XML' } | ||
return xquery:eval($query, $vars) | return xquery:eval($query, $vars) | ||
− | </ | + | </pre> |
|} | |} | ||
Line 71: | Line 77: | ||
{| width='100%' | {| width='100%' | ||
− | |- | + | |- valign="top" |
− | | width='120' | ''' | + | | width='120' | '''Signature''' |
− | | | + | |<pre>xquery:eval-update( |
− | |- | + | $query as xs:anyAtomicType, |
+ | $bindings as map(*)? := (), | ||
+ | $options as map(*)? := () | ||
+ | ) as item()*</pre> | ||
+ | |- valign="top" | ||
| '''Summary''' | | '''Summary''' | ||
− | |Evaluates a query as updating expression. 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 for all arguments are the same as for | + | |Evaluates a query as updating expression. 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 for all arguments are the same as for {{Function||xquery:eval}}. |
− | |- | + | |- valign="top" |
| '''Errors''' | | '''Errors''' | ||
|{{Error|update|#Errors}} the query contains no [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|limit|#Errors}} query execution exceeded memory limit.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query. | |{{Error|update|#Errors}} the query contains no [[XQuery Update#Updating Expressions|updating expressions]].<br/>{{Error|permission|#Errors}} insufficient permissions for evaluating the query.<br/>{{Error|timeout|#Errors}} query execution exceeded timeout.<br/>{{Error|limit|#Errors}} query execution exceeded memory limit.<br/>{{Error|nested|#Errors}} nested query evaluation is not allowed.<br/>Any other error that may occur while evaluating the query. | ||
− | |- | + | |- valign="top" |
| '''Examples''' | | '''Examples''' | ||
| | | | ||
* Removes entries from a temporary databases and returns an info string: | * Removes entries from a temporary databases and returns an info string: | ||
− | < | + | <pre lang='xquery'> |
xquery:eval-update(" | xquery:eval-update(" | ||
− | delete node db: | + | delete node db:get('tmp')/*, |
update:output('TEMPORARY DATABASE WAS CLEANED UP') | update:output('TEMPORARY DATABASE WAS CLEANED UP') | ||
") | ") | ||
− | </ | + | </pre> |
|} | |} | ||
− | = | + | =Parsing= |
==xquery:parse== | ==xquery:parse== | ||
− | |||
− | |||
{| width='100%' | {| width='100%' | ||
− | |- | + | |- valign="top" |
− | | width='120' | ''' | + | | width='120' | '''Signature''' |
− | | | + | |<pre>xquery:parse( |
− | |- | + | $query as xs:anyAtomicType, |
+ | $options as map(*)? := map { } | ||
+ | ) as item()?</pre> | ||
+ | |- valign="top" | ||
| '''Summary''' | | '''Summary''' | ||
|Parses the specified {{Code|$query}} as XQuery module and returns the resulting query plan. If the query is of type {{Code|xs:anyURI}}, the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type {{Code|xs:string}}. The {{Code|$options}} parameter influences the output: | |Parses the specified {{Code|$query}} as XQuery module and returns the resulting query plan. If the query is of type {{Code|xs:anyURI}}, the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type {{Code|xs:string}}. The {{Code|$options}} parameter influences the output: | ||
Line 109: | Line 120: | ||
* {{Code|pass}}: by default, the option is {{Code|false}}. If an error is raised, the line/column number and the optional file uri will refer to the location of the function call. If the option is enabled, the line/column and file uri will be adopted from the raised error. | * {{Code|pass}}: by default, the option is {{Code|false}}. If an error is raised, the line/column number and the optional file uri will refer to the location of the function call. 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|fn:doc}}. | * {{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}}. | ||
− | |- | + | |- valign="top" |
| '''Errors''' | | '''Errors''' | ||
|Any error that may occur while parsing the query. | |Any error that may occur while parsing the query. | ||
− | |- | + | |- valign="top" |
| '''Examples''' | | '''Examples''' | ||
| | | | ||
* {{Code|xquery:parse("1 + 3")}} returns: | * {{Code|xquery:parse("1 + 3")}} returns: | ||
− | < | + | <pre lang="xml"> |
<MainModule updating="false"> | <MainModule updating="false"> | ||
<QueryPlan compiled="false"> | <QueryPlan compiled="false"> | ||
Line 125: | Line 136: | ||
</QueryPlan> | </QueryPlan> | ||
</MainModule> | </MainModule> | ||
− | </ | + | </pre> |
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
− | |||
|} | |} | ||
Line 147: | Line 144: | ||
==xquery:fork-join== | ==xquery:fork-join== | ||
+ | |||
+ | {{Announce|Updated with Version 11:}} Options added. | ||
{| width='100%' | {| width='100%' | ||
− | |- | + | |- valign="top" |
− | | width='120' | ''' | + | | width='120' | '''Signature''' |
− | | | + | |<pre>xquery:fork-join( |
− | |- | + | $functions as function(*)*, |
+ | $options as map(*)? := map { } | ||
+ | ) as item()*</pre> | ||
+ | |- valign="top" | ||
|'''Summary''' | |'''Summary''' | ||
− | |This function executes the supplied (non-updating) functions in parallel. | + | |This function executes the supplied (non-updating) {{Code|$functions}} in parallel. The following {{Code|$options}} are available: |
− | |- | + | * {{Code|parallel}}: Maximum number of parallel threads. If the value is smaller than {{Code|1}}, or if the option is omitted, the number of available processors is used. |
+ | * {{Code|result}}: Suppress or return the function results (default: {{Code|true}}). | ||
+ | * {{Code|errors}}: Ignore or raise errors (default: {{Code|true}}). | ||
+ | |- valign="top" | ||
| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * | + | * Request 100 URLs, use at most 8 parallel threads: |
− | + | <pre lang='xquery'> | |
− | |||
− | |||
− | |||
− | |||
− | < | ||
xquery:fork-join( | xquery:fork-join( | ||
− | for $segment in 1 to | + | for $segment in 1 to 100 |
let $url := 'http://url.com/path/' || $segment | let $url := 'http://url.com/path/' || $segment | ||
− | return function() { http:send-request((), $url) } | + | return function() { http:send-request((), $url) }, |
+ | map { 'parallel': 8 } | ||
) | ) | ||
− | </ | + | </pre> |
− | |- | + | * Parallel sleep function calls. The function is expected to finish in 1 second if the system has at least 2 cores: |
+ | <pre lang='xquery'> | ||
+ | let $f := function() { prof:sleep(1000) } | ||
+ | return xquery:fork-join(($f, $f)) | ||
+ | </pre> | ||
+ | |- valign="top" | ||
|'''Errors''' | |'''Errors''' | ||
|{{Error|error|#Errors}} an unexpected error occurred. | |{{Error|error|#Errors}} an unexpected error occurred. | ||
Line 181: | Line 187: | ||
! width="110"|Code | ! width="110"|Code | ||
|Description | |Description | ||
− | |- | + | |- valign="top" |
|{{Code|permission}} | |{{Code|permission}} | ||
|Insufficient permissions for evaluating the query. | |Insufficient permissions for evaluating the query. | ||
− | |- | + | |- valign="top" |
|{{Code|update}} | |{{Code|update}} | ||
|[[XQuery Update#Updating Expressions|updating expression]] found or expected. | |[[XQuery Update#Updating Expressions|updating expression]] found or expected. | ||
− | |- | + | |- valign="top" |
|{{Code|timeout}} | |{{Code|timeout}} | ||
|Query execution exceeded timeout. | |Query execution exceeded timeout. | ||
− | |- | + | |- valign="top" |
|{{Code|memory}} | |{{Code|memory}} | ||
|Query execution exceeded memory limit. | |Query execution exceeded memory limit. | ||
− | |- | + | |- valign="top" |
|{{Code|nested}} | |{{Code|nested}} | ||
|Nested query evaluation is not allowed. | |Nested query evaluation is not allowed. | ||
− | |- | + | |- valign="top" |
|{{Code|error}} | |{{Code|error}} | ||
|An unexpected error occurred. | |An unexpected error occurred. | ||
Line 203: | Line 209: | ||
=Changelog= | =Changelog= | ||
− | ;Version | + | ;Version 11 |
+ | |||
+ | * Updated: {{Function||xquery:fork-join}}: Options added. | ||
+ | * Updated: The Clark notation was replaced with the [[XQuery 3.0#Expanded QNames|Expanded QNames]] notation. | ||
+ | |||
+ | ;Version 10 | ||
− | * Deleted: xquery:parse-uri (merged with | + | * Deleted: xquery:parse-uri (merged with {{Function||xquery:parse}}) |
− | * Updated: | + | * Updated: {{Function||xquery:parse}}: {{$query}} can additionally be of type {{Code|xs:anyURI}}. |
;Version 9.2 | ;Version 9.2 | ||
− | * Deleted: xquery:invoke, xquery:invoke-update (merged with | + | * Deleted: xquery:invoke, xquery:invoke-update (merged with {{Function||xquery:eval}} and {{Function||xquery:eval-update}}) |
;Version 9.0 | ;Version 9.0 | ||
− | * Added: | + | * Added: {{Function||xquery:invoke-update}} |
− | * Updated: | + | * Updated: {{Function||xquery:eval}}: {{Code|pass}} option added |
− | * Updated: | + | * Updated: {{Function||xquery:parse}}, {{Function||xquery:parse-uri}}: {{Code|base-uri}} option added |
− | * Updated: xquery:update renamed to | + | * Updated: xquery:update renamed to {{Function||xquery:eval-update}} |
* Updated: error codes updated; errors now use the module namespace | * Updated: error codes updated; errors now use the module namespace | ||
;Version 8.5 | ;Version 8.5 | ||
− | * Added: | + | * Added: {{Function||xquery:fork-join}} |
− | * Updated: | + | * Updated: {{Function||xquery:eval}}: {{Code|base-uri}} option added |
* Updated: Relative URIs will always be resolved against the static base URI of the query | * Updated: Relative URIs will always be resolved against the static base URI of the query | ||
* Deleted: xquery:type (moved to [[Profiling Module]]) | * Deleted: xquery:type (moved to [[Profiling Module]]) | ||
Line 229: | Line 240: | ||
;Version 8.4 | ;Version 8.4 | ||
− | * Added: | + | * Added: {{Function||xquery:parse-uri}} |
− | * Updated: | + | * Updated: {{Function||xquery:parse}}: {{Code|pass}} option added |
;Version 8.0 | ;Version 8.0 | ||
− | * Added: xquery:update, | + | * Added: xquery:update, {{Function||xquery:parse}} |
* Deleted: xquery:evaluate (opened databases will now be closed by main query) | * Deleted: xquery:evaluate (opened databases will now be closed by main query) | ||
Line 243: | Line 254: | ||
;Version 7.8 | ;Version 7.8 | ||
− | * Added: | + | * Added: {{Function||xquery:evaluate}} |
* Updated: used variables must be explicitly declared in the query string. | * Updated: used variables must be explicitly declared in the query string. | ||
This module was introduced with Version 7.3. Functions have been adopted from the obsolete Utility Module. | This module was introduced with Version 7.3. Functions have been adopted from the obsolete Utility Module. |
Latest revision as of 18:39, 1 December 2023
This XQuery Module contains functions for parsing and evaluating XQuery strings at runtime, and to run code in parallel.
Contents
Conventions[edit]
All functions and errors in this module are assigned to the http://basex.org/modules/xquery
namespace, which is statically bound to the xquery
prefix.
Evaluation[edit]
xquery:eval[edit]
Updated with Version 11: The Clark notation was replaced with the Expanded QNames notation.
Signature | xquery:eval( $query as xs:anyAtomicType, $bindings as map(*)? := map { }, $options as map(*)? := map { } ) as item()* |
Summary | Evaluates the supplied $query and returns the resulting items. If the query is of type xs:anyURI , the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type xs:string .
Variables and context items can be declared via
The
|
Errors | update : the query contains updating expressions.permission : insufficient permissions for evaluating the query.timeout : query execution exceeded timeout.limit : query execution exceeded memory limit.nested : nested query evaluation is not allowed.Any other error that may occur while evaluating the query. |
Examples |
xquery:eval(xs:anyURI('cleanup.xq'))
xquery:eval("//country", map { '': db:get('factbook') })
xquery:eval(".", map { '': 'XML' }),
xquery:eval("declare variable $xml external; $xml", map { 'xml': 'XML' }),
xquery:eval(
"declare namespace pref='URI';
declare variable $pref:xml external;
$pref:xml",
map { '{URI}xml': 'XML' }
)
declare namespace pref = 'URI';
xquery:eval("declare variable $xml external; $xml", map { xs:QName('xml'): 'XML' }),
let $query := "declare namespace pref='URI';
declare variable $pref:xml external;
$pref:xml"
let $vars := map { xs:QName('pref:xml'): 'XML' }
return xquery:eval($query, $vars)
|
xquery:eval-update[edit]
Signature | xquery:eval-update( $query as xs:anyAtomicType, $bindings as map(*)? := (), $options as map(*)? := () ) as item()* |
Summary | Evaluates a query as updating expression. All updates will be added to the Pending Update List of the main query and performed after the evaluation of the main query. The rules for all arguments are the same as for xquery:eval .
|
Errors | update : the query contains no updating expressions.permission : insufficient permissions for evaluating the query.timeout : query execution exceeded timeout.limit : query execution exceeded memory limit.nested : nested query evaluation is not allowed.Any other error that may occur while evaluating the query. |
Examples |
xquery:eval-update("
delete node db:get('tmp')/*,
update:output('TEMPORARY DATABASE WAS CLEANED UP')
")
|
Parsing[edit]
xquery:parse[edit]
Signature | xquery:parse( $query as xs:anyAtomicType, $options as map(*)? := map { } ) as item()? |
Summary | Parses the specified $query as XQuery module and returns the resulting query plan. If the query is of type xs:anyURI , the module located at this URI will be retrieved (a relative URI will be resolved against the static base URI). Otherwise, the input is expected to be of type xs:string . The $options parameter influences the output:
|
Errors | Any error that may occur while parsing the query. |
Examples |
<MainModule updating="false">
<QueryPlan compiled="false">
<Arith op="+">
<Int value="1" type="xs:integer"/>
<Int value="3" type="xs:integer"/>
</Arith>
</QueryPlan>
</MainModule>
|
Parallelized Execution[edit]
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.
xquery:fork-join[edit]
Updated with Version 11: Options added.
Signature | xquery:fork-join( $functions as function(*)*, $options as map(*)? := map { } ) as item()* |
Summary | This function executes the supplied (non-updating) $functions in parallel. The following $options are available:
|
Examples |
xquery:fork-join(
for $segment in 1 to 100
let $url := 'http://url.com/path/' || $segment
return function() { http:send-request((), $url) },
map { 'parallel': 8 }
)
let $f := function() { prof:sleep(1000) }
return xquery:fork-join(($f, $f))
|
Errors | error : an unexpected error occurred.
|
Errors[edit]
Code | Description |
---|---|
permission
|
Insufficient permissions for evaluating the query. |
update
|
updating expression found or expected. |
timeout
|
Query execution exceeded timeout. |
memory
|
Query execution exceeded memory limit. |
nested
|
Nested query evaluation is not allowed. |
error
|
An unexpected error occurred. |
Changelog[edit]
- Version 11
- Updated:
xquery:fork-join
: Options added. - Updated: The Clark notation was replaced with the Expanded QNames notation.
- Version 10
- Deleted: xquery:parse-uri (merged with
xquery:parse
) - Updated:
xquery:parse
: Template:$query can additionally be of typexs:anyURI
.
- Version 9.2
- Deleted: xquery:invoke, xquery:invoke-update (merged with
xquery:eval
andxquery:eval-update
)
- Version 9.0
- Added:
xquery:invoke-update
- Updated:
xquery:eval
:pass
option added - Updated:
xquery:parse
,xquery:parse-uri
:base-uri
option added - Updated: xquery:update renamed to
xquery:eval-update
- Updated: error codes updated; errors now use the module namespace
- Version 8.5
- Added:
xquery:fork-join
- Updated:
xquery:eval
:base-uri
option added - Updated: Relative URIs will always be resolved against the static base URI of the query
- Deleted: xquery:type (moved to Profiling Module)
- Version 8.4
- Added:
xquery:parse-uri
- Updated:
xquery:parse
:pass
option added
- Version 8.0
- Added: xquery:update,
xquery:parse
- Deleted: xquery:evaluate (opened databases will now be closed by main query)
- Version 7.8.2
- Added:
$options
argument
- Version 7.8
- Added:
xquery:evaluate
- Updated: used variables must be explicitly declared in the query string.
This module was introduced with Version 7.3. Functions have been adopted from the obsolete Utility Module.