cloud-fan commented on code in PR #49202:
URL: https://github.com/apache/spark/pull/49202#discussion_r1897206718
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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:
is this check too strong? We only require the common expression to not
contain subqueries.
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