GitHub user carsonwang opened a pull request:
https://github.com/apache/spark/pull/11090
[SPARK-13185][SQL] Reuse Calendar object in DateTimeUtils.StringToDate
method to improve performance
The java `Calendar` object is expensive to create. I have a sub query like
this `SELECT a, b, c FROM table UV WHERE (datediff(UV.visitDate,
'1997-01-01')>=0 AND datediff(UV.visitDate, '2015-01-01')<=0))`
The table stores `visitDate` as String type and has 3 billion records. A
`Calendar` object is created every time `DateTimeUtils.stringToDate` is called.
By reusing the `Calendar` object, I saw about 20 seconds performance
improvement for this stage.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/carsonwang/spark SPARK-13185
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/11090.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 #11090
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commit 5bbbf917b326062c30a017a76203e97cdb0d0e74
Author: Carson Wang <[email protected]>
Date: 2016-02-05T07:02:24Z
Reuse Calendar object in StringToDate method
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