GitHub user eatoncys opened a pull request:
https://github.com/apache/spark/pull/19022
[Spark-21807][SQL]The getAliasedConstraints function in LogicalPlan will
take a long time when number of expressions is greater than 100
## What changes were proposed in this pull request?
The getAliasedConstraints fuction in LogicalPlan.scala will clone the
expression set when an element added,
and it will take a long time. This PR add a function to add multiple
elements at once to reduce the clone time.
Before modified, the cost of getAliasedConstraints is:
100 expressions: 41 seconds
150 expressions: 466 seconds
After modified, the cost of getAliasedConstraints is:
100 expressions: 1.8 seconds
150 expressions: 6.5 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)
}
(Please fill in changes proposed in this fix)
## How was this patch tested?
(Please explain how this patch was tested. E.g. unit tests, integration
tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise,
remove this)
Run new added test.
Please review http://spark.apache.org/contributing.html before opening a
pull request.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/eatoncys/spark getAliasedConstraints
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/19022.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #19022
----
commit 80af01add6c0169c7cad0286afc748d845cd1327
Author: 10129659 <[email protected]>
Date: 2017-08-22T07:47:27Z
The getAliasedConstraints function will take a long time when expression is
greater than 100
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