[SPARK-20366] [SQL] Fix recursive join reordering: inside joins are not reordered #17668
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Test build #75891 has finished for PR 17668 at commit
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LGTM, merging to master! |
peter-toth
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Oct 6, 2018
…t reordered
## What changes were proposed in this pull request?
If a plan has multi-level successive joins, e.g.:
```
Join
/ \
Union t5
/ \
Join t4
/ \
Join t3
/ \
t1 t2
```
Currently we fail to reorder the inside joins, i.e. t1, t2, t3.
In join reorder, we use `OrderedJoin` to indicate a join has been ordered, such that when transforming down the plan, these joins don't need to be rerodered again.
But there's a problem in the definition of `OrderedJoin`:
The real join node is a parameter, but not a child. This breaks the transform procedure because `mapChildren` applies transform function on parameters which should be children.
In this patch, we change `OrderedJoin` to a class having the same structure as a join node.
## How was this patch tested?
Add a corresponding test case.
Author: wangzhenhua <[email protected]>
Closes apache#17668 from wzhfy/recursiveReorder.
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What changes were proposed in this pull request?
If a plan has multi-level successive joins, e.g.:
Currently we fail to reorder the inside joins, i.e. t1, t2, t3.
In join reorder, we use
OrderedJointo indicate a join has been ordered, such that when transforming down the plan, these joins don't need to be rerodered again.But there's a problem in the definition of
OrderedJoin:The real join node is a parameter, but not a child. This breaks the transform procedure because
mapChildrenapplies transform function on parameters which should be children.In this patch, we change
OrderedJointo a class having the same structure as a join node.How was this patch tested?
Add a corresponding test case.