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https://issues.apache.org/jira/browse/HIVE-14002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15331503#comment-15331503
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Jesus Camacho Rodriguez edited comment on HIVE-14002 at 6/15/16 10:30 AM:
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Thanks for reviewing [~ashutoshc]. In fact, _operator.acceptLimitPushdown()_ is
used to bail out if the operator does not accept the limit pushdown. This is
the same logic that was used for pushing it from the Limit operator and the
logic seems sound.
Further, if we cannot backtrack a column from the top RS to the bottom RS, we
bail out too (in fact, the new _checkKeys_ method checks that).
was (Author: jcamachorodriguez):
Thanks for reviewing [~ashutoshc]. In fact, _operator.acceptLimitPushdown()_ is
used to bail out if the operator does not accept the limit pushdown. This is
the same logic that was used for pushing it from the Limit operator, thus I
expect that the operators are properly classified and it is sound.
Further, if we cannot backtrack a column from the top RS to the bottom RS, we
bail out too (in fact, the new _checkKeys_ method checks that).
> Extend limit propagation to subsequent RS operators
> ---------------------------------------------------
>
> Key: HIVE-14002
> URL: https://issues.apache.org/jira/browse/HIVE-14002
> Project: Hive
> Issue Type: Improvement
> Components: Physical Optimizer
> Affects Versions: 2.2.0
> Reporter: Nita Dembla
> Assignee: Jesus Camacho Rodriguez
> Attachments: HIVE-14002.01.patch, HIVE-14002.patch
>
>
> In some occasions, for instance when RS dedup does not kick in, it is useful
> to propagate the limit to subsequent RS operators, as this will reduce
> intermediary results and impact performance. This issue covers that extension.
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