MarkLogic 12 EA 1 Product Documentationop:lock-for-update
op:lock-for-update( [$lockUriCol as item()?] ) as map:map
Summary
Gets an early lock on documents that will be updated later in the pipeline with an operation like remove() or write(). Documents are always locked, but for complex pipelines, it can be beneficial to lock the document early, so to minimize the potential for lock contention.
| Parameters | |
|---|---|
| $lockUriCol | If this column is not specified then it assumes a column 'uri' is present. This can be a string of the uri column name or an op:col. Use op:view-col or op:schema-col if you need to identify columns in the two views that have the same column name. |
Usage Notes
op:lock-for-update() needs to be run as an update transaction. Use 'declare option xdmp:update "true";' in the prolog, or use xdmp:invoke/xdmp:invoke-function with update="true".See Also
- Optic API for Multi-Model Data Access in the Application Developer's Guide
Example
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
declare option xdmp:update "true";
op:from-doc-descriptors(map:entry("uri", "/optic/update/write1.xml")=>map:with("doc", <doc>write1</doc>))
=>op:lock-for-update()
=>op:write()
=>op:result();
Example
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
declare option xdmp:update "true";
op:from-doc-descriptors(map:entry("uri", "/optic/update/write1.xml")=>map:with("doc", <doc>write1</doc>))
=>op:lock-for-update("uri")
=>op:write()
=>op:result();
Example
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
declare option xdmp:update "true";
op:from-doc-descriptors(map:entry("uri", "/optic/update/write.xml")=>map:with("doc", <doc>write1</doc>), "myQualifier")
=>op:lock-for-update(op:view-col("myQualifier","uri"))
=>op:write(op:doc-cols("myQualifier", ("uri", "doc")))
=>op:result();