GitHub user viirya opened a pull request:
https://github.com/apache/spark/pull/15667
[SPARK-18107][SQL] Insert overwrite statement runs much slower in spark-sql
than it does in hive-client
## What changes were proposed in this pull request?
As reported on the jira, insert overwrite statement runs much slower in
Spark, compared with hive-client.
It seems there is a patch
[HIVE-11940](https://github.com/apache/hive/commit/ba21806b77287e237e1aa68fa169d2a81e07346d)
which largely improves insert overwrite performance on Hive. HIVE-11940 is
patched after Hive 2.0.0.
Because Spark SQL uses older Hive library, we can not benefit from such
improvement.
The reporter verified that there is also a big performance gap between Hive
1.2.1 and Hive 2.0.1 on insert overwrite execution.
Instead of upgrading to Hive 2.0 in Spark SQL, which might not be a trivial
task, this patch provides an approach to delete the partition before asking
Hive to load data files into the partition.
Note: since `Hive.loadTable` also uses the function to replace files, it
should has the same issue. We can take the same approach to delete the table
first. I will upgrade this to include this.
## How was this patch tested?
Jenkins tests.
There are existing tests using insert overwrite statement. Those tests
should be passed. I added a new test to specially test insert overwrite into
partition.
For performance issue, as I don't have Hive 2.0 environment, this needs the
reporter to verify this patch. Please refer to the jira.
Please review
https://cwiki.apache.org/confluence/display/SPARK/Contributing+to+Spark before
opening a pull request.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/viirya/spark-1 improve-hive-insertoverwrite
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/15667.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 #15667
----
commit 81dbeb19e61a67a287a5762e391517eb55a20721
Author: Liang-Chi Hsieh <vii...@gmail.com>
Date: 2016-10-27T09:29:16Z
Drop partition before insert overwrite to Hive table.
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