fqaiser94 commented on a change in pull request #29812:
URL: https://github.com/apache/spark/pull/29812#discussion_r491929282
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/WithFields.scala
##########
@@ -17,16 +17,29 @@
package org.apache.spark.sql.catalyst.optimizer
-import org.apache.spark.sql.catalyst.expressions.WithFields
+import scala.collection.mutable
+
+import org.apache.spark.sql.catalyst.expressions.{Expression, GetStructField,
WithFields}
import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
import org.apache.spark.sql.catalyst.rules.Rule
/**
- * Combines all adjacent [[WithFields]] expression into a single
[[WithFields]] expression.
+ * Optimizes [[WithFields]] expression chains.
*/
-object CombineWithFields extends Rule[LogicalPlan] {
+object OptimizeWithFields extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
+ case WithFields(structExpr, names, values) if names.distinct.length !=
names.length =>
+ val newNames = mutable.ArrayBuffer.empty[String]
+ val newValues = mutable.ArrayBuffer.empty[Expression]
+ names.zip(values).reverse.foreach { case (name, value) =>
+ if (!newNames.contains(name)) {
Review comment:
should use `resolver` here otherwise I think we will have correct-ness
issues.
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/WithFields.scala
##########
@@ -17,16 +17,29 @@
package org.apache.spark.sql.catalyst.optimizer
-import org.apache.spark.sql.catalyst.expressions.WithFields
+import scala.collection.mutable
+
+import org.apache.spark.sql.catalyst.expressions.{Expression, GetStructField,
WithFields}
import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
import org.apache.spark.sql.catalyst.rules.Rule
/**
- * Combines all adjacent [[WithFields]] expression into a single
[[WithFields]] expression.
+ * Optimizes [[WithFields]] expression chains.
*/
-object CombineWithFields extends Rule[LogicalPlan] {
+object OptimizeWithFields extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
+ case WithFields(structExpr, names, values) if names.distinct.length !=
names.length =>
+ val newNames = mutable.ArrayBuffer.empty[String]
+ val newValues = mutable.ArrayBuffer.empty[Expression]
+ names.zip(values).reverse.foreach { case (name, value) =>
+ if (!newNames.contains(name)) {
+ newNames += name
+ newValues += value
+ }
+ }
+ WithFields(structExpr, names = newNames.reverse.toSeq, valExprs =
newValues.reverse.toSeq)
Review comment:
For my understanding, can you explain how we expect to benefit from this
optimization?
I ask because we do this kind of deduplication inside of `WithFields`
already as part of the `foldLeft` operation
[here](https://github.com/apache/spark/blob/d01594e8d186e63a6c3ce361e756565e830d5237/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypeCreator.scala#L578).
It will only keep the last `valExpr` for each `name`. So I think the optimized
logical plan will be the same with or without this optimization in all
scenarios? CMIIW
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/WithFields.scala
##########
@@ -17,16 +17,29 @@
package org.apache.spark.sql.catalyst.optimizer
-import org.apache.spark.sql.catalyst.expressions.WithFields
+import scala.collection.mutable
+
+import org.apache.spark.sql.catalyst.expressions.{Expression, GetStructField,
WithFields}
import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
import org.apache.spark.sql.catalyst.rules.Rule
/**
- * Combines all adjacent [[WithFields]] expression into a single
[[WithFields]] expression.
+ * Optimizes [[WithFields]] expression chains.
*/
-object CombineWithFields extends Rule[LogicalPlan] {
+object OptimizeWithFields extends Rule[LogicalPlan] {
def apply(plan: LogicalPlan): LogicalPlan = plan transformAllExpressions {
+ case WithFields(structExpr, names, values) if names.distinct.length !=
names.length =>
Review comment:
could this `case` statement be after the next `case` statement? So that
we combine the chains first before deduplicating?
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