pratham76 commented on code in PR #58656:
URL: https://github.com/apache/spark/pull/58656#discussion_r4148351471
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/subquery.scala:
##########
@@ -398,62 +406,393 @@ object RewritePredicateSubquery extends
Rule[LogicalPlan] with PredicateHelper {
(newExpr, newPlan)
}
+ /**
+ * Same as [[rewriteExistentialExpr]], but it also returns the newly
introduced attributes, and
+ * it only rewrites the existential sub-queries for which `canRewrite`
returns true. A sub-query
+ * that is not rewritten stays in the returned expression as it is, and is
not descended into:
+ * rewriting an existential sub-query nested in its join condition would
graft an existence join
+ * onto the plan for an `exists` reference that the sub-query left in place
may never evaluate.
+ */
private def rewriteExistentialExprWithAttrs(
exprs: Seq[Expression],
- plan: LogicalPlan): (Option[Expression], LogicalPlan, Seq[Attribute]) = {
+ plan: LogicalPlan,
+ canRewrite: Expression => Boolean = _ => true): (Option[Expression],
LogicalPlan,
+ Seq[Attribute]) = {
var newPlan = plan
val introducedAttrs = ArrayBuffer.empty[Attribute]
- val newExprs = exprs.map { e =>
- e.transformDownWithPruning(_.containsAnyPattern(EXISTS_SUBQUERY,
IN_SUBQUERY)) {
- case Exists(sub, _, _, conditions, subHint) =>
- val exists = AttributeReference("exists", BooleanType, nullable =
false)()
- val existenceJoin = ExistenceJoin(exists)
- val newCondition = conditions.reduceLeftOption(And)
- newPlan =
- buildJoin(newPlan, rewriteDomainJoinsIfPresent(newPlan, sub,
newCondition),
- existenceJoin, newCondition, subHint)
- introducedAttrs += exists
- exists
- case Not(InSubquery(values, ListQuery(sub, _, _, _, conditions,
subHint))) =>
- val exists = AttributeReference("exists", BooleanType, nullable =
false)()
- // Deduplicate conflicting attributes if any.
- val newSub = dedupSubqueryOnSelfJoin(newPlan, sub, Some(values))
- val inConditions = values.zip(newSub.output).map(EqualTo.tupled)
- // To handle a null-aware predicate not-in-subquery in nested
conditions
- // (e.g., `v > 0 OR t1.id NOT IN (SELECT id FROM t2)`), we transform
- // `inCondition` (t1.id=t2.id) into `(inCondition) OR
ISNULL(inCondition)`.
- //
- // For example, `SELECT * FROM t1 WHERE v > 0 OR t1.id NOT IN
(SELECT id FROM t2)`
- // is transformed into a plan below;
- // == Optimized Logical Plan ==
- // Project [id#78, v#79]
- // +- Filter ((v#79 > 0) OR NOT exists#83)
- // +- Join ExistenceJoin(exists#83), ((id#78 = id#80) OR
isnull((id#78 = id#80)))
- // :- Relation[id#78,v#79] parquet
- // +- Relation[id#80] parquet
- val nullAwareJoinConds = inConditions.map(c => Or(c, IsNull(c)))
- val finalJoinCond = (nullAwareJoinConds ++
conditions).reduceLeft(And)
- val joinHint = JoinHint(None, subHint)
- newPlan = Join(newPlan,
- rewriteDomainJoinsIfPresent(newPlan, newSub, Some(finalJoinCond)),
- ExistenceJoin(exists), Some(finalJoinCond), joinHint)
- introducedAttrs += exists
- Not(exists)
- case InSubquery(values, ListQuery(sub, _, _, _, conditions, subHint))
=>
- val exists = AttributeReference("exists", BooleanType, nullable =
false)()
- // Deduplicate conflicting attributes if any.
- val newSub = dedupSubqueryOnSelfJoin(newPlan, sub, Some(values))
- val inConditions = values.zip(newSub.output).map(EqualTo.tupled)
- val newConditions = (inConditions ++
conditions).reduceLeftOption(And)
- val joinHint = JoinHint(None, subHint)
- newPlan = Join(newPlan, rewriteDomainJoinsIfPresent(newPlan, newSub,
newConditions),
- ExistenceJoin(exists), newConditions, joinHint)
- introducedAttrs += exists
- exists
+ // Builds the replacement of a sub-query expression under that
expression's origin and with
+ // its tags, as TreeNode.transformDownWithPruning does for the nodes a
rule replaces. Without
+ // it every node built below, the `exists` attribute and the join
conditions included, would
+ // take the origin of the enclosing operator, and a runtime error raised
from the rewritten
+ // condition would quote that operator rather than the sub-query fragment.
+ def replacing(sq: Expression)(replacement: => Expression): Expression = {
+ val newExpr = CurrentOrigin.withOrigin(sq.origin)(replacement)
+ newExpr.copyTagsFrom(sq)
+ newExpr
+ }
+ def rewrite(expr: Expression): Expression = {
+ if (!expr.containsAnyPattern(EXISTS_SUBQUERY, IN_SUBQUERY)) {
+ return expr
+ }
+ expr match {
+ case sq @ Exists(sub, _, _, conditions, subHint) if canRewrite(sq) =>
+ replacing(sq) {
+ val exists = AttributeReference("exists", BooleanType, nullable =
false)()
+ val existenceJoin = ExistenceJoin(exists)
+ val newCondition = conditions.reduceLeftOption(And)
+ newPlan =
+ buildJoin(newPlan, rewriteDomainJoinsIfPresent(newPlan, sub,
newCondition),
+ existenceJoin, newCondition, subHint)
+ introducedAttrs += exists
+ exists
+ }
+ case sq @ Not(InSubquery(values, ListQuery(sub, _, _, _, conditions,
subHint)))
+ if canRewrite(sq) =>
+ replacing(sq) {
+ val exists = AttributeReference("exists", BooleanType, nullable =
false)()
+ // Deduplicate conflicting attributes if any.
+ val newSub = dedupSubqueryOnSelfJoin(newPlan, sub, Some(values))
+ val inConditions = values.zip(newSub.output).map(EqualTo.tupled)
+ // To handle a null-aware predicate not-in-subquery in nested
conditions
+ // (e.g., `v > 0 OR t1.id NOT IN (SELECT id FROM t2)`), we
transform
+ // `inCondition` (t1.id=t2.id) into `(inCondition) OR
ISNULL(inCondition)`.
+ //
+ // For example, `SELECT * FROM t1 WHERE v > 0 OR t1.id NOT IN
(SELECT id FROM t2)`
+ // is transformed into a plan below;
+ // == Optimized Logical Plan ==
+ // Project [id#78, v#79]
+ // +- Filter ((v#79 > 0) OR NOT exists#83)
+ // +- Join ExistenceJoin(exists#83), ((id#78 = id#80) OR
isnull((id#78 = id#80)))
+ // :- Relation[id#78,v#79] parquet
+ // +- Relation[id#80] parquet
+ val nullAwareJoinConds = inConditions.map(c => Or(c, IsNull(c)))
+ val finalJoinCond = (nullAwareJoinConds ++
conditions).reduceLeft(And)
+ val joinHint = JoinHint(None, subHint)
+ newPlan = Join(newPlan,
+ rewriteDomainJoinsIfPresent(newPlan, newSub,
Some(finalJoinCond)),
+ ExistenceJoin(exists), Some(finalJoinCond), joinHint)
+ introducedAttrs += exists
+ Not(exists)
+ }
+ case sq @ InSubquery(values, ListQuery(sub, _, _, _, conditions,
subHint))
+ if canRewrite(sq) =>
+ replacing(sq) {
+ val exists = AttributeReference("exists", BooleanType, nullable =
false)()
+ // Deduplicate conflicting attributes if any.
+ val newSub = dedupSubqueryOnSelfJoin(newPlan, sub, Some(values))
+ val inConditions = values.zip(newSub.output).map(EqualTo.tupled)
+ val newConditions = (inConditions ++
conditions).reduceLeftOption(And)
+ val joinHint = JoinHint(None, subHint)
+ newPlan = Join(newPlan, rewriteDomainJoinsIfPresent(newPlan,
newSub, newConditions),
+ ExistenceJoin(exists), newConditions, joinHint)
+ introducedAttrs += exists
+ exists
+ }
+ // A sub-query that `canRewrite` declined is left as it is, children
included.
+ case sq @ (_: Exists | Not(_: InSubquery) | _: InSubquery) => sq
+ case other => other.mapChildren(rewrite)
}
}
+ val newExprs = exprs.map(rewrite)
(newExprs.reduceOption(And), newPlan, introducedAttrs.toSeq)
}
+
+ /**
+ * Returns true if `e` references any of the attributes produced by `plan`.
+ */
+ private def referencesPlan(e: Expression, plan: LogicalPlan): Boolean = {
+ // Iterates the references and probes the output set, which allocates
nothing.
Review Comment:
Corrected. The comment now says this avoids materialising the intersection
rather than claiming it
allocates nothing, and notes that the membership probes still construct
wrappers.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
