fred-db commented on code in PR #38497:
URL: https://github.com/apache/spark/pull/38497#discussion_r1026135835
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/EliminateResolvedHint.scala:
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@@ -31,20 +34,35 @@ object EliminateResolvedHint extends Rule[LogicalPlan] {
// This is also called in the beginning of the optimization phase, and as a
result
// is using transformUp rather than resolveOperators.
def apply(plan: LogicalPlan): LogicalPlan = {
- val pulledUp = plan transformUp {
+ val joinsWithHints = plan transformUp {
case j: Join if j.hint == JoinHint.NONE =>
val (newLeft, leftHints) = extractHintsFromPlan(j.left)
val (newRight, rightHints) = extractHintsFromPlan(j.right)
val newJoinHint = JoinHint(mergeHints(leftHints),
mergeHints(rightHints))
j.copy(left = newLeft, right = newRight, hint = newJoinHint)
}
- pulledUp.transformUp {
+ val shouldPullHintsIntoSubqueries =
SQLConf.get.getConf(SQLConf.PULL_HINTS_INTO_SUBQUERIES)
+ val joinsAndSubqueriesWithHints = if (shouldPullHintsIntoSubqueries) {
+ pullHintsIntoSubqueries(joinsWithHints)
+ } else {
+ joinsWithHints
+ }
+ joinsAndSubqueriesWithHints.transformUp {
case h: ResolvedHint =>
hintErrorHandler.joinNotFoundForJoinHint(h.hints)
h.child
}
}
+ def pullHintsIntoSubqueries(plan: LogicalPlan): LogicalPlan = {
+
plan.transformAllExpressionsUpWithPruning(_.containsPattern(PLAN_EXPRESSION)) {
Review Comment:
If there are two nested subqueries, we'd want to extract hints from the
innermost first, and then from the outer one. Otherwise, hints for the
innermost will end up in the outermost subquery. I think in practice nested
subqueries are not supported, but I think it's better to keep it this way if we
decide to support them at some point.
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