GitHub user minji-kim opened a pull request:
https://github.com/apache/drill/pull/437
Map variance() and stddev() to var_samp() and stddev_samp() respectivâ¦
â¦ely, and allow for DrillReduceAggregateRule to apply to them
Right now, variance() and stddev() is not mapped to var_samp() and
stddev_samp() respectively, and they cannot be reduced to sums of squares (by
DrillReduceAggregateRule). DrillReduceAggregateRule allows variance/stddev
functions to be aggregated over 2-phase aggregation. Without this,
stddev/variance is always done in a single phase aggregation. Added test cases
to verify.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/minji-kim/drill DRILL-4521
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/437.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 #437
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commit 033786aaaf0d1fd16cac84ba2a2010e610a8e9a4
Author: Minji Kim <[email protected]>
Date: 2016-03-22T00:20:10Z
Map variance() and stddev() to var_samp() and stddev_samp() respectively,
and allow for DrillReduceAggregateRule to apply to them
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