[SPARK-11675][SQL] Remove shuffle hash joins. #9645
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LGTM |
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Test build #45691 has finished for PR 9645 at commit
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Test build #2047 has finished for PR 9645 at commit
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I'm going to merge this. |
asfgit
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Nov 12, 2015
Author: Reynold Xin <[email protected]> Closes #9645 from rxin/SPARK-11675. (cherry picked from commit e49e723) Signed-off-by: Reynold Xin <[email protected]>
dskrvk
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Nov 13, 2015
Author: Reynold Xin <[email protected]> Closes apache#9645 from rxin/SPARK-11675.
ghost
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Mar 18, 2016
## What changes were proposed in this pull request? ShuffledHashJoin (also outer join) is removed in 1.6, in favor of SortMergeJoin, which is more robust and also fast. ShuffledHashJoin is still useful in this case: 1) one table is much smaller than the other one, then cost to build a hash table on smaller table is smaller than sorting the larger table 2) any partition of the small table could fit in memory. This PR brings back ShuffledHashJoin, basically revert apache#9645, and fix the conflict. Also merging outer join and left-semi join into the same class. This PR does not implement full outer join, because it's not implemented efficiently (requiring build hash table on both side). A simple benchmark (one table is 5x smaller than other one) show that ShuffledHashJoin could be 2X faster than SortMergeJoin. ## How was this patch tested? Added new unit tests for ShuffledHashJoin. Author: Davies Liu <[email protected]> Closes apache#11788 from davies/shuffle_join.
roygao94
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Mar 22, 2016
## What changes were proposed in this pull request? ShuffledHashJoin (also outer join) is removed in 1.6, in favor of SortMergeJoin, which is more robust and also fast. ShuffledHashJoin is still useful in this case: 1) one table is much smaller than the other one, then cost to build a hash table on smaller table is smaller than sorting the larger table 2) any partition of the small table could fit in memory. This PR brings back ShuffledHashJoin, basically revert apache#9645, and fix the conflict. Also merging outer join and left-semi join into the same class. This PR does not implement full outer join, because it's not implemented efficiently (requiring build hash table on both side). A simple benchmark (one table is 5x smaller than other one) show that ShuffledHashJoin could be 2X faster than SortMergeJoin. ## How was this patch tested? Added new unit tests for ShuffledHashJoin. Author: Davies Liu <[email protected]> Closes apache#11788 from davies/shuffle_join.
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