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https://issues.apache.org/jira/browse/DRILL-4530?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15326679#comment-15326679
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ASF GitHub Bot commented on DRILL-4530:
---------------------------------------
GitHub user amansinha100 opened a pull request:
https://github.com/apache/drill/pull/519
DRILL-4530: Optimize partition pruning with metadata caching for the …
…single partition case.
- Enhance PruneScanRule to detect single partitions based on referenced
dirs in the filter.
- Keep a new status of EXPANDED_PARTIAL for FileSelection.
- Create separate .directories metadata file to prune directories first
before files.
- Introduce cacheFileRoot attribute to keep track of the parent directory
of the cache file after partition pruning.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/amansinha100/incubator-drill DRILL-4530-1
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/519.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #519
----
commit 9c9687e804fa05c8f4b7b065738c458cb88bf5c4
Author: Aman Sinha <[email protected]>
Date: 2016-03-25T19:55:59Z
DRILL-4530: Optimize partition pruning with metadata caching for the single
partition case.
- Enhance PruneScanRule to detect single partitions based on referenced
dirs in the filter.
- Keep a new status of EXPANDED_PARTIAL for FileSelection.
- Create separate .directories metadata file to prune directories first
before files.
- Introduce cacheFileRoot attribute to keep track of the parent directory
of the cache file after partition pruning.
----
> Improve metadata cache performance for queries with single partition
> ---------------------------------------------------------------------
>
> Key: DRILL-4530
> URL: https://issues.apache.org/jira/browse/DRILL-4530
> Project: Apache Drill
> Issue Type: Improvement
> Components: Query Planning & Optimization
> Affects Versions: 1.6.0
> Reporter: Aman Sinha
> Assignee: Aman Sinha
> Fix For: 1.7.0
>
>
> Consider two types of queries which are run with Parquet metadata caching:
> {noformat}
> query 1:
> SELECT col FROM `A/B/C`;
> query 2:
> SELECT col FROM `A` WHERE dir0 = 'B' AND dir1 = 'C';
> {noformat}
> For a certain dataset, the query1 elapsed time is 1 sec whereas query2
> elapsed time is 9 sec even though both are accessing the same amount of data.
> The user expectation is that they should perform roughly the same. The main
> difference comes from reading the bigger metadata cache file at the root
> level 'A' for query2 and then applying the partitioning filter. query1 reads
> a much smaller metadata cache file at the subdirectory level.
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