GitHub user JoshRosen opened a pull request:
https://github.com/apache/spark/pull/13484
[SPARK-15742][SQL] Reduce temp collections allocations in TreeNode
transform methods
In Catalyst's TreeNode transform methods we end up calling
`productIterator.map(...).toArray` in a number of places, which is slightly
inefficient because it needs to allocate an `ArrayBuilder` and grow a temporary
array. Since we already know the size of the final output (`productArity`), we
can simply allocate an array up-front and use a while loop to consume the
iterator and populate the array.
For most workloads, this performance difference is negligible but it does
make a measurable difference in optimizer performance for queries that operate
over very wide schemas (such as the benchmark queries in #13456).
/cc @ericl @marmbrus
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/JoshRosen/spark treenode-productiterator-map
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/13484.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 #13484
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commit 4e7e758d279bd3d1c8de741500f2de51e8cc4ed1
Author: Josh Rosen <[email protected]>
Date: 2016-06-02T23:55:33Z
Improve performance of tree transformation.
commit da79ec6207d4b78d0ebc461cacd37e14d6e4d2e3
Author: Josh Rosen <[email protected]>
Date: 2016-06-02T23:58:24Z
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