[jira] [Commented] (FLINK-6326) add ProjectMergeRule at logical optimization stage

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-6326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15974484#comment-15974484 ] 

ASF GitHub Bot commented on FLINK-6326:
---------------------------------------

GitHub user godfreyhe opened a pull request:

    https://github.com/apache/flink/pull/3739

    [FLINK-6326] [table] add ProjectMergeRule at logical optimization stage

    add ProjectMergeRule to merge projections

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/godfreyhe/flink FLINK-6326

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/flink/pull/3739.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #3739
    
----
commit 1c14d02a4776becbc4147b576d5ee20dd8e15d24
Author: godfreyhe <go...@163.com>
Date:   2017-04-19T11:46:18Z

    [FLINK-6326] [table] add ProjectMergeRule at logical optimization stage

----


> 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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