[
https://issues.apache.org/jira/browse/HIVE-11882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14877430#comment-14877430
]
Illya Yalovyy commented on HIVE-11882:
--------------------------------------
When I checked last time the API for the early exit was in place but actual
code didn't use it.
I'll go ahead and double check the trunk (master). If it is fixed already I'll
close this ticket.
> Fetch optimizer should stop source files traversal once it exceeds the
> hive.fetch.task.conversion.threshold
> -----------------------------------------------------------------------------------------------------------
>
> Key: HIVE-11882
> URL: https://issues.apache.org/jira/browse/HIVE-11882
> Project: Hive
> Issue Type: Improvement
> Components: Physical Optimizer
> Affects Versions: 1.0.0
> Reporter: Illya Yalovyy
>
> Hive 1.0's fetch optimizer tries to optimize queries of the form "select <C>
> from <T> where <F> limit <L>" to a fetch task (see the
> hive.fetch.task.conversion property). This optimization gets the lengths of
> all the files in the specified partition and does some comparison against a
> threshold value to determine whether it should use a fetch task or not (see
> the hive.fetch.task.conversion.threshold property). This process of getting
> the length of all files. One of the main problems in this optimization is the
> fetch optimizer doesn't seem to stop once it exceeds the
> hive.fetch.task.conversion.threshold. It works fine on HDFS, but could cause
> a significant performance degradation on other supported file systems.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
