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https://issues.apache.org/jira/browse/FLINK-12424?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kurt Young closed FLINK-12424.
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Resolution: Implemented
Fix Version/s: 1.9.0
merge in 1.9.0: e038a801a87f25b30a1b47ffe5710e5d9bd44c9b
> Supports dag (multiple-sinks query) optimization
> ------------------------------------------------
>
> Key: FLINK-12424
> URL: https://issues.apache.org/jira/browse/FLINK-12424
> Project: Flink
> Issue Type: New Feature
> Components: Table SQL / Planner
> Reporter: godfrey he
> Assignee: godfrey he
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.9.0
>
> Attachments: image-2019-05-07-13-33-02-793.png
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Currently, Flink planner will optimize the plan in {{writeToSink}} method. If
> there are more than one sink in a query, each sink-tree will be optimized
> independent and the result execution plans are also completely independent.
> Actually, there is a high probability of duplicate computing for a
> multiple-sinks query. This issue aims to resolve the above problem.
> The basic idea of the solution is as following:
> 1. lazy optimization: does not optimize the plan in {{writeToSink}} method,
> just puts the plan into a collection.
> 2. whole plan optimization and execution: a new {{execute}} method is added
> in {{TableEnvironment}}, this method will trigger whole plan optimization and
> execute the job.
> The basic idea of dag (multiple-sinks query) optimization:
> 1. decompose the dag into different block, the leaf block is the common
> sub-plan
> 2. optimize each block from leaf block to root block, each block only needs
> to be optimized once
> e.g.
> {code:scala}
> val table = tableEnv.sqlQuery("select * from (select a as a1, b as b1 from
> MyTable where a > 0) t1, (select b as b2, c as c2 from MyTable where c is not
> null) t2 where a1 = b2")
> tableEnv.registerTable("TempTable", table)
> val table1 = tableEnv.sqlQuery("select a1, b1 from TempTable where a1 >= 70")
> tableEnv.writeToSink(table1, Sink1)
> val table2 = tableEnv.sqlQuery("select a1, c2 from TempTable where a1 < 70")
> tableEnv.writeToSink(table2, Sink2)
> {code}
> !image-2019-05-07-13-33-02-793.png!
> the above plan will be decomposed into 3 blocks, block1 is the input of
> block2 and block3. block2 and block3 will be optimized after block1 has been
> optimized.
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