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https://issues.apache.org/jira/browse/SPARK-25071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16582419#comment-16582419
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Sujith edited comment on SPARK-25071 at 8/16/18 12:11 PM:
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[~hyukjin.kwon] [~ZenWzh] [~srowen] I have a doubt based on above
conversation, if we consider purely row count not rawDatasize/totalsize then
there is a possibility where row size can be very large for a particular table
even though the number of rows will be same or slightly high, and we are ending
up broadcasting table with larger data size?
was (Author: s71955):
[~hyukjin.kwon] [~ZenWzh]a [~srowen] I have a doubt based on above
conversation, if we consider purely row count not rawDatasize/totalsize then
there is a possibility where row size can be very large for a particular table
even though the number of rows will be same or slightly high, and we are ending
up broadcasting table with larger data size?
> BuildSide is coming not as expected with join queries
> -----------------------------------------------------
>
> Key: SPARK-25071
> URL: https://issues.apache.org/jira/browse/SPARK-25071
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.3.1
> Environment: Spark 2.3.1
> Hadoop 2.7.3
> Reporter: Ayush Anubhava
> Priority: Major
>
> *BuildSide is not coming as expected.*
> Pre-requisites:
> *CBO is set as true & spark.sql.cbo.joinReorder.enabled= true.*
> *import org.apache.spark.sql.execution.joins.BroadcastHashJoinExec*
> *Steps:*
> *Scenario 1:*
> spark.sql("CREATE TABLE small3 (c1 bigint) TBLPROPERTIES ('numRows'='2',
> 'rawDataSize'='600','totalSize'='80000000000')")
> spark.sql("CREATE TABLE big3 (c1 bigint) TBLPROPERTIES ('numRows'='2',
> 'rawDataSize'='60000000', 'totalSize'='800')")
> val plan = spark.sql("select * from small3 t1 join big3 t2 on (t1.c1 =
> t2.c1)").queryExecution.executedPlan
> val buildSide =
> plan.children.head.asInstanceOf[BroadcastHashJoinExec].buildSide
> println(buildSide)
>
> *Result 1:*
> scala> val plan = spark.sql("select * from small3 t1 join big3 t2 on (t1.c1 =
> t2.c1)").queryExecution.executedPlan
> plan: org.apache.spark.sql.execution.SparkPlan =
> *(2) BroadcastHashJoin [c1#0L|#0L], [c1#1L|#1L], Inner, BuildRight
> :- *(2) Filter isnotnull(c1#0L)
> : +- HiveTableScan [c1#0L|#0L], HiveTableRelation `default`.`small3`,
> org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, [c1#0L|#0L]
> +- BroadcastExchange HashedRelationBroadcastMode(List(input[0, bigint,
> false]))
> +- *(1) Filter isnotnull(c1#1L)
> +- HiveTableScan [c1#1L|#1L], HiveTableRelation `default`.`big3`,
> org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, [c1#1L|#1L]
> scala> val buildSide =
> plan.children.head.asInstanceOf[BroadcastHashJoinExec].buildSide
> buildSide: org.apache.spark.sql.execution.joins.BuildSide = BuildRight
> scala> println(buildSide)
> *BuildRight*
>
> *Scenario 2:*
> spark.sql("CREATE TABLE small4 (c1 bigint) TBLPROPERTIES ('numRows'='2',
> 'rawDataSize'='600','totalSize'='80')")
> spark.sql("CREATE TABLE big4 (c1 bigint) TBLPROPERTIES ('numRows'='2',
> 'rawDataSize'='60000000', 'totalSize'='800')")
> val plan = spark.sql("select * from small4 t1 join big4 t2 on (t1.c1 =
> t2.c1)").queryExecution.executedPlan
> val buildSide =
> plan.children.head.asInstanceOf[BroadcastHashJoinExec].buildSide
> println(buildSide)
> *Result 2:*
> scala> val plan = spark.sql("select * from small4 t1 join big4 t2 on (t1.c1 =
> t2.c1)").queryExecution.executedPlan
> plan: org.apache.spark.sql.execution.SparkPlan =
> *(2) BroadcastHashJoin [c1#4L|#4L], [c1#5L|#5L], Inner, BuildRight
> :- *(2) Filter isnotnull(c1#4L)
> : +- HiveTableScan [c1#4L|#4L], HiveTableRelation `default`.`small4`,
> org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, [c1#4L|#4L]
> +- BroadcastExchange HashedRelationBroadcastMode(List(input[0, bigint,
> false]))
> +- *(1) Filter isnotnull(c1#5L)
> +- HiveTableScan [c1#5L|#5L], HiveTableRelation `default`.`big4`,
> org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe, [c1#5L|#5L]
> scala> val buildSide =
> plan.children.head.asInstanceOf[BroadcastHashJoinExec].buildSide
> buildSide: org.apache.spark.sql.execution.joins.BuildSide = *BuildRight*
>
>
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