Github user liancheng commented on a diff in the pull request:
https://github.com/apache/spark/pull/13893#discussion_r73156772
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/planning/patterns.scala
---
@@ -64,10 +64,17 @@ object PhysicalOperation extends PredicateHelper {
val substitutedFields =
fields.map(substitute(aliases)).asInstanceOf[Seq[NamedExpression]]
(Some(substitutedFields), filters, other,
collectAliases(substitutedFields))
- case Filter(condition, child) if condition.deterministic =>
+ case Filter(condition, child) =>
val (fields, filters, other, aliases) =
collectProjectsAndFilters(child)
- val substitutedCondition = substitute(aliases)(condition)
- (fields, filters ++
splitConjunctivePredicates(substitutedCondition), other, aliases)
+
+ // Deterministic parts of filter condition placed before
non-deterministic predicates could
+ // be pushed down safely.
+ val (pushDown, rest) =
--- End diff --
I also think that silently dropping nondeterministic filters can be
dangerous. Maybe we should just return all operators beneath the top-most
nondeterministic filter as the bottom operator?
For example, say we have a plan tree like this:
```
Project a, b
Filter a > 1
Filter b < 3
Filter RAND(42) > 0.5
Filter c < 2
TableScan t
```
We should return the following result:
```
(
// Project list
Seq(a, b),
// Deterministic filters
Seq(b < 3, a > 1),
// The top-most nondeterministic operator filter with all operators
beneath
Filter(
RAND(42) > 0.5,
Filter(c < 2,
TableScan(t)))
)
```
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