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https://issues.apache.org/jira/browse/FLINK-6326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15974585#comment-15974585
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ASF GitHub Bot commented on FLINK-6326:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3739#discussion_r112192763
--- Diff:
flink-libraries/flink-table/src/test/scala/resources/testProjectMerge.out ---
@@ -0,0 +1,156 @@
+== Abstract Syntax Tree ==
--- End diff --
This file can be removed, IMO.
> add ProjectMergeRule at logical optimization stage
> --------------------------------------------------
>
> Key: FLINK-6326
> URL: https://issues.apache.org/jira/browse/FLINK-6326
> Project: Flink
> Issue Type: New Feature
> Components: Table API & SQL
> Reporter: godfrey he
> Assignee: godfrey he
>
> add ProjectMergeRule to merge projections. Some SQLs can not push projection
> into scan without this rule.
> e.g.
> table1: id: int, name: string
> table2: id: string, score: double, first: string, last: string
> {code}
> SELECT a.id, b.score FROM
> (SELECT id FROM table1 WHERE id > 10) a
> LEFT OUTER JOIN
> (SELECT * FROM table2) b
> ON CAST(a.id AS VARCHAR) = b.id
> {code}
> {code}
> == Optimized Logical Plan without ProjectMergeRule ==
> DataSetCalc(select=[id, score])
> DataSetJoin(where=[=(id0, id1)], join=[id, id0, id1, score, first, last],
> joinType=[LeftOuterJoin])
> DataSetCalc(select=[id, CAST(id) AS id0], where=[>(id, 10)])
> BatchTableSourceScan(table=[[table1]], fields=[id])
> BatchTableSourceScan(table=[[table2]], fields=[id, score, first, last])
> {code}
> {code}
> == Optimized Logical Plan with ProjectMergeRule ==
> DataSetCalc(select=[id, score])
> DataSetJoin(where=[=(id0, id1)], join=[id, id0, id1, score],
> joinType=[LeftOuterJoin])
> DataSetCalc(select=[id, CAST(id) AS id0], where=[>(id, 10)])
> BatchTableSourceScan(table=[[table1]], fields=[id])
> BatchTableSourceScan(table=[[table2]], fields=[id, score])
> {code}
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