[GitHub] [spark] maryannxue commented on a change in pull request #26289: [SPARK-28560][SQL][followup] support the build side to local shuffle reader as far as possible in BroadcastHashJoin

[GitBox <gi...@apache.org>]

maryannxue commented on a change in pull request #26289: [SPARK-28560][SQL][followup] support the build side to local shuffle reader as far as possible in BroadcastHashJoin
URL: https://github.com/apache/spark/pull/26289#discussion_r340724212
 
 

 ##########
 File path: sql/core/src/main/scala/org/apache/spark/sql/execution/adaptive/OptimizeLocalShuffleReader.scala
 ##########
 @@ -56,16 +68,27 @@ case class OptimizeLocalShuffleReader(conf: SQLConf) extends Rule[SparkPlan] {
         case e: ShuffleExchangeExec => e
       }.length
     }
-
+    // Check whether additional shuffle introduced. If introduced, revert the local reader.
     val numExchangeBefore = numExchanges(EnsureRequirements(conf).apply(plan))
-    val numExchangeAfter = numExchanges(EnsureRequirements(conf).apply(optimizedPlan))
-
-    if (numExchangeAfter > numExchangeBefore) {
-      logDebug("OptimizeLocalShuffleReader rule is not applied due" +
+    val numExchangeAfter = numExchanges(EnsureRequirements(conf).apply(withProbeSideLocalReader))
+    val optimizedPlan = if (numExchangeAfter > numExchangeBefore) {
+      logDebug("OptimizeLocalShuffleReader rule is not applied in the probe side due" +
         " to additional shuffles will be introduced.")
       plan
     } else {
-      optimizedPlan
+      withProbeSideLocalReader
+    }
+    // Add the local reader in build side and and do not need to check whether
+    // additional shuffle introduced.
+    optimizedPlan.transformDown {
+      case join: BroadcastHashJoinExec if (join.buildSide == BuildLeft &&
 
 Review comment:
   Shall we check for `BroadcastQueryStageExec` for which we shouldn't add a local shuffle reader?
   
   Another alternative is we apply this part of the rule after `EnsureRequirements` and match `BroadcastExchangeExec` over `QueryStageExec` instead.

----------------------------------------------------------------
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.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org