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https://issues.apache.org/jira/browse/BEAM-7151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17122846#comment-17122846
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Beam JIRA Bot commented on BEAM-7151:
-------------------------------------
This issue is P2 but has been unassigned without any comment for 60 days so it
has been labeled "stale-P2". If this issue is still affecting you, we care!
Please comment and remove the label. Otherwise, in 14 days the issue will be
moved to P3.
Please see https://beam.apache.org/contribute/jira-priorities/ for a detailed
explanation of what these priorities mean.
> Support conjunction clause when it's only equi-join
> ---------------------------------------------------
>
> Key: BEAM-7151
> URL: https://issues.apache.org/jira/browse/BEAM-7151
> Project: Beam
> Issue Type: Sub-task
> Components: dsl-sql
> Reporter: Rui Wang
> Priority: P2
> Labels: stale-P2
>
> conjunction_clause: function_call(function_parameter, ...) | field_access |
> column
> function_parameter: function_call | field_access
> In Beam, equi-join is implemented by CoGBK, which requires both join inputs
> (assume binary join) to build PCollection of KV<Row, Row>, where the key is
> join key.
> For equi-join, conjunction clause is essentially an equation. In order to
> build KV<Row, Row>, it requires that columns from different sides of equation
> should come from different join input. For example, a + b = 2 cannot be used
> to build join key but a = 2 - b can. So rewriting is required for clauses
> when it does not satisfy this property.
> It also implies that not every clause is rewritable. Say the clause is f(a,
> b) = 3, in which a is from left input and b is from right input. If this
> function f is not splittable, such that we cannot move a or b to right side
> of equation, then we cannot support this clause in BeamSQL's join.
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