op:exists-join
op:exists-join( $leftPlan as map:map, $rightPlan as map:map, [$keys as map:map*], [$condition as map:map?] ) as map:map
Summary
This method is a filtering join that filters based on whether the join exists or not but doesn't add any columns.
It filters the left row set to the rows that have a join in the right row set.
| Parameters | |
|---|---|
| $leftPlan | The row set from the left view. |
| $rightPlan | The row set from the right view. |
| $keys | The equijoin from one or more calls to the op:on function. |
| $condition | A boolean expression that filters the join output rows. |
Example
(: It filters out {'r1':1, 'k1':'a'} in p1 as value 'a' exists in column 'k2' of p2 :)
xquery version "1.0-ml";
import module namespace op="http://marklogic.com/optic"
at "/MarkLogic/optic.xqy";
op:from-literals((
map:entry("r1", 1) => map:with("k1", "a"),
map:entry("r1", 2) => map:with("k1", "b")
))
=> op:exists-join(
op:from-literals((
map:entry("r2", 3) => map:with("k2", "a"),
map:entry("r2", 4) => map:with("k2", "c")
)),
op:on("k1", "k2")
)
=> op:result()
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