GitHub user sureshsubbiah opened a pull request:
https://github.com/apache/incubator-trafodion/pull/1163
[TRAFODION-2622] Left join with other_join_predicate on table alone i…
…s slow
This change is due to Hans Zeller.
The other join predicate in a hash join is evaluated before the hash join,
so that failing rows can be nulll instantiated directly. This avoids
a temporary join explosion when the join predicate matches most rows but
the other_join_predicate fails most rows. This change will be extended
to merge joins later.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sureshsubbiah/incubator-trafodion 2622
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/1163.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 #1163
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commit de3348941e05c8afaa731af3798aaea46ac40cac
Author: Suresh Subbiah <sureshs@apache.org>
Date: 2017-07-04T15:31:12Z
[TRAFODION-2622] Left join with other_join_predicate on table alone is slow
This change is due to Hans Zeller.
The other join predicate in a hash join is evaluated before the hash join,
so that failing rows can be nulll instantiated directly. This avoids
a temporary join explosion when the join predicate matches most rows but
the other_join_predicate fails most rows. This change will be extended
to merge joins later.
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