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https://issues.apache.org/jira/browse/HIVE-15023?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15591142#comment-15591142
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Jesus Camacho Rodriguez commented on HIVE-15023:
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I checked a bit further the code and I think the approach I propose above might
not be as simple as I thought, since we would need to create the task and thus
it is not simply moving the clause from one place to another...
I think it is OK then to proceed, but if we leave the fix as it is now, please
add a comment to the new _if_ statement in SimpleFetchOptimizer explaining why
we are bailing out there. Thanks
> SimpleFetchOptimizer needs to optimize limit=0
> ----------------------------------------------
>
> Key: HIVE-15023
> URL: https://issues.apache.org/jira/browse/HIVE-15023
> Project: Hive
> Issue Type: Sub-task
> Reporter: Pengcheng Xiong
> Assignee: Pengcheng Xiong
> Attachments: HIVE-15023.01.patch
>
>
> on current master
> {code}
> hive> explain select key from src limit 0;
> OK
> STAGE DEPENDENCIES:
> Stage-0 is a root stage
> STAGE PLANS:
> Stage: Stage-0
> Fetch Operator
> limit: 0
> Processor Tree:
> TableScan
> alias: src
> Statistics: Num rows: 500 Data size: 5312 Basic stats: COMPLETE
> Column stats: NONE
> Select Operator
> expressions: key (type: string)
> outputColumnNames: _col0
> Statistics: Num rows: 500 Data size: 5312 Basic stats: COMPLETE
> Column stats: NONE
> Limit
> Number of rows: 0
> Statistics: Num rows: 0 Data size: 0 Basic stats: NONE Column
> stats: NONE
> ListSink
> Time taken: 7.534 seconds, Fetched: 20 row(s)
> {code}
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