GitHub user lianhuiwang opened a pull request:
https://github.com/apache/spark/pull/7423
[SPARK-8160][SQL]Support using external sorting to run aggregate
according to UnsafeFixedWidthAggregationMap, this PR implement external
aggregation when each task has no enough memory. firstly when memory is not
enough it spills UnsafeAppendOnlyMap to disk. when inserting is finished,
merge in-memory map and disk's spill files and return final aggregation value
of each key.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/lianhuiwang/spark external-aggregate
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/7423.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 #7423
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commit 4d7a3102d1627eeb877128bce4233c43991f5a13
Author: Lianhui Wang <[email protected]>
Date: 2015-07-15T16:27:42Z
init commit for external aggregation
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