Github user srinathshankar commented on a diff in the pull request:
https://github.com/apache/spark/pull/14912#discussion_r77383932
--- Diff:
sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/FilterPushdownSuite.scala
---
@@ -171,6 +172,27 @@ class FilterPushdownSuite extends PlanTest {
comparePlans(optimized, correctAnswer)
}
+ test("push down filters that are combined") {
+ // The following predicate ('a === 2 || 'a === 3) && ('c > 10 || 'a
=== 2)
+ // will be simplified as ('a == 2) || ('c > 10 && 'a == 3).
+ // ('a === 2 || 'a === 3) can be pushed down. But the simplified one
can't.
--- End diff --
So what happens if I just have the predicate
(a = 2) || (c > 10 && a = 3)
Will anything will be pushed down ? Have you considered instead modifying
the boolean simplification logic.
Another approach that will catch these cases is as follows:
1.a Convert filters to conjunctive normal form
1.b combine filters
1.c Push filters
1.a, b and c will be run in a batch until fixed point.
Follow this batch by BooleanSimplification -- this can find and extract
common factors for efficiency.
Overall, cnf may maximize the potential for filter push down
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