GitHub user ioana-delaney opened a pull request:
https://github.com/apache/spark/pull/17546
[SPARK-20233] [SQL] Apply star-join filter heuristics to dynamic
programming join enumeration
## What changes were proposed in this pull request?
Implements star-join filter to reduce the search space for dynamic
programming join enumeration. Consider the following join graph:
```
T1 D1 - T2 - T3
\ /
F1
|
D2
star-join: {F1, D1, D2}
non-star: {T1, T2, T3}
```
The following join combinations will be generated:
```
level 0: (F1), (D1), (D2), (T1), (T2), (T3)
level 1: {F1, D1}, {F1, D2}, {T2, T3}
level 2: {F1, D1, D2}
level 3: {F1, D1, D2, T1}, {F1, D1, D2, T2}
level 4: {F1, D1, D2, T1, T2}, {F1, D1, D2, T2, T3 }
level 6: {F1, D1, D2, T1, T2, T3}
```
## How was this patch tested?
New test suite ```StarJOinCostBasedReorderSuite.scala```.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/ioana-delaney/spark starSchemaCBOv3
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/17546.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 #17546
----
commit 5eb9b30d4d3ae4d6bc4d137af5ec09a876df805a
Author: Ioana Delaney <[email protected]>
Date: 2017-04-06T04:04:20Z
[SPARK-20233] Implement star-join filter for join enumeration.
----
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