[jira] [Commented] (HIVE-26618) Add setting to turn on/off removing sections of a query plan known never produces rows

["Stamatis Zampetakis (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-26618?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17615628#comment-17615628 ] 

Stamatis Zampetakis commented on HIVE-26618:
--------------------------------------------

Why to we need this toggle? Did we identify cases where the previous optimization is preferred?

> Add setting to turn on/off removing sections of a query plan known never produces rows
> --------------------------------------------------------------------------------------
>
>                 Key: HIVE-26618
>                 URL: https://issues.apache.org/jira/browse/HIVE-26618
>             Project: Hive
>          Issue Type: Improvement
>          Components: CBO
>            Reporter: Krisztian Kasa
>            Assignee: Krisztian Kasa
>            Priority: Major
>              Labels: pull-request-available
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> HIVE-26524 introduced an optimization to remove sections of query plan known never produces rows.
> Add a setting into hive conf to turn on/off this optimization.
> When the optimization is turned off restore the legacy behavior:
> * represent empty result operator with {{HiveSortLimit}} 0
> * disable {{HiveRemoveEmptySingleRules}}



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