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https://issues.apache.org/jira/browse/SPARK-21807?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16137819#comment-16137819
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Liang-Chi Hsieh commented on SPARK-21807:
-----------------------------------------
This is a known issue. Currently we provide a SQL conf
{{spark.sql.constraintPropagation.enabled}} that can disable constraint
propagation.
> The getAliasedConstraints function in LogicalPlan will take a long time when
> number of expressions is greater than 100
> ------------------------------------------------------------------------------------------------------------------------
>
> Key: SPARK-21807
> URL: https://issues.apache.org/jira/browse/SPARK-21807
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 2.2.0
> Reporter: eaton
>
> The getAliasedConstraints fuction in LogicalPlan.scala will clone the
> expression set when an element added,
> and it will take a long time.
> Before modified, the cost of getAliasedConstraints is:
> 100 expressions: 41 seconds
> 150 expressions: 466 seconds
> The test is like this:
> test("getAliasedConstraints") {
> val expressionNum = 150
> val aggExpression = (1 to expressionNum).map(i => Alias(Count(Literal(1)),
> s"cnt$i")())
> val aggPlan = Aggregate(Nil, aggExpression, LocalRelation())
> val beginTime = System.currentTimeMillis()
> val expressions = aggPlan.validConstraints
> println(s"validConstraints cost: ${System.currentTimeMillis() - beginTime}ms")
> // The size of Aliased expression is n * (n - 1) / 2 + n
> assert( expressions.size === expressionNum * (expressionNum - 1) / 2 +
> expressionNum)
> }
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