zml1206 commented on code in PR #49202:
URL: https://github.com/apache/spark/pull/49202#discussion_r1897364136
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
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@@ -1978,6 +1988,62 @@ object PushPredicateThroughNonJoin extends
Rule[LogicalPlan] with PredicateHelpe
case _ => false
}
}
+
+ /**
+ * Use [[With]] to rewrite condition which contains attribute that are not
cheap and be consumed
+ * multiple times. Each predicate generates one or 0 With. For facilitates
subsequent merge
+ * [[With]], use the same CommonExpressionDef ids for different [[With]].
+ */
+ private def rewriteConditionByWith(
+ cond: Seq[Expression],
+ aliasMap: AttributeMap[Alias]): Seq[Expression] = {
+ if (!SQLConf.get.getConf(SQLConf.ALWAYS_INLINE_COMMON_EXPR)) {
+ val canRewriteConf = cond.filter(canRewriteByWith)
+ if (canRewriteConf.nonEmpty) {
+ val replaceWithMap = canRewriteConf.reduce(And)
+ .collect { case a: Attribute => a }
+ .groupBy(identity)
+ .transform((_, v) => v.size)
+ .filter(m => aliasMap.contains(m._1) && m._2 > 1)
+ .map(m => m._1 -> trimAliases(aliasMap.getOrElse(m._1, m._1)))
+ .filter(m => !CollapseProject.isCheap(m._2))
+ val defsMap = AttributeMap(replaceWithMap.map(m => m._1 ->
CommonExpressionDef(m._2)))
+ val refsMap = AttributeMap(defsMap.map(m => m._1 -> new
CommonExpressionRef(m._2)))
+ cond.map(rewriteByWith(_, defsMap, refsMap))
+ } else cond
+ } else cond
+ }
+
+ private def rewriteConditionByWith(
+ cond: Expression,
+ aliasMap: AttributeMap[Alias]): Expression = {
+ if (!SQLConf.get.getConf(SQLConf.ALWAYS_INLINE_COMMON_EXPR)) {
+ rewriteConditionByWith(splitConjunctivePredicates(cond),
aliasMap).reduce(And)
+ } else cond
+ }
+
+ // With does not support inline subquery
+ private def canRewriteByWith(expr: Expression): Boolean = {
+ !expr.containsPattern(PLAN_EXPRESSION)
Review Comment:
Both rewriting subqueries and pushing down predicates are in batch "operator
optimization before inferring filters". Pushing down predicates may cause
SubqueryExpression to contain common refs, and then rewriting subqueries cannot
replace common refs.
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