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From "Rahul Challapalli (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DRILL-4786) Improve metadata cache performance for queries with multiple partitions
Date Thu, 18 Aug 2016 17:33:20 GMT

    [ https://issues.apache.org/jira/browse/DRILL-4786?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15426855#comment-15426855

Rahul Challapalli commented on DRILL-4786:

Verified the feature and automated the test cases

> Improve metadata cache performance for queries with multiple partitions
> -----------------------------------------------------------------------
>                 Key: DRILL-4786
>                 URL: https://issues.apache.org/jira/browse/DRILL-4786
>             Project: Apache Drill
>          Issue Type: Improvement
>          Components: Metadata, Query Planning & Optimization
>    Affects Versions: 1.7.0
>            Reporter: Aman Sinha
>            Assignee: Aman Sinha
>             Fix For: 1.8.0
> Consider  queries of the following type run against Parquet data with metadata caching:
> {noformat}
> SELECT col FROM `A` WHERE dir0 = 'B`' AND dir1 IN ('1', '2', '3')
> {noformat}
> For such queries, Drill will read the metadata cache file from the top level directory
'A', which is not very efficient since we are only interested in the files  from some subdirectories
of 'B'.   DRILL-4530 improves the performance of such queries when the leaf level directory
is a single partition.  Here, there are 3 subpartitions due to the IN list.   We can build
upon the DRILL-4530 enhancement by at least reading the cache file from the immediate parent
level  `/A/B`  instead of the top level.  
> The goal of this JIRA is to improve performance for such types of queries.  

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