Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/13846#discussion_r68240312
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
---
@@ -206,15 +205,33 @@ object RemoveAliasOnlyProject extends
Rule[LogicalPlan] {
object EliminateSerialization extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transform {
case d @ DeserializeToObject(_, _, s: SerializeFromObject)
- if d.outputObjectType == s.inputObjectType =>
+ if d.outputObjAttr.dataType == s.inputObjAttr.dataType =>
// Adds an extra Project here, to preserve the output expr id of
`DeserializeToObject`.
// We will remove it later in RemoveAliasOnlyProject rule.
- val objAttr =
- Alias(s.child.output.head, s.child.output.head.name)(exprId =
d.output.head.exprId)
+ val objAttr = Alias(s.inputObjAttr, s.inputObjAttr.name)(exprId =
d.outputObjAttr.exprId)
Project(objAttr :: Nil, s.child)
+
case a @ AppendColumns(_, _, _, s: SerializeFromObject)
- if a.deserializer.dataType == s.inputObjectType =>
+ if a.deserializer.dataType == s.inputObjAttr.dataType =>
AppendColumnsWithObject(a.func, s.serializer, a.serializer, s.child)
+
+ // If there is a `SerializeFromObject` under typed filter and its
input object type is same with
+ // the typed filter's deserializer, we can convert typed filter to
normal filter without
+ // deserialization in condition, and push it down through
`SerializeFromObject`.
+ // e.g. `ds.map(...).filter(...)` can be optimized by this rule to
save extra deserialization,
+ // but `ds.map(...).as[AnotherType].filter(...)` can not be optimized.
+ case f @ TypedFilter(_, _, s: SerializeFromObject)
+ if f.deserializer.dataType == s.inputObjAttr.dataType =>
+ s.copy(child = f.withObject(s.child))
--- End diff --
Well, it's true, and `Filter` can be any other unary operators whose output
is derived from its child, e.g. Sort.
However, I don't think `ds.map(...).filter(byExpr).filter(byFunc)` is a
common case, i.e. mixing typed and untyped operations interlaced. If there is
an easy and general way to optimize it, I'm happy to have it, or I'd like to
leave it.
what do you think?
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