Skip to content

[SPARK-28333][SQL] NULLS FIRST for DESC and NULLS LAST for ASC #25147

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
shivusondur wants to merge 1 commit into from
Closed

[SPARK-28333][SQL] NULLS FIRST for DESC and NULLS LAST for ASC #25147

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
1 change: 1 addition & 0 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/dsl/package.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -120,6 +120,7 @@ package object dsl {
def asc_nullsLast: SortOrder = SortOrder(expr, Ascending, NullsLast, Set.empty)
def desc: SortOrder = SortOrder(expr, Descending)
def desc_nullsFirst: SortOrder = SortOrder(expr, Descending, NullsFirst, Set.empty)
def desc_nullsLast: SortOrder = SortOrder(expr, Descending, NullsLast, Set.empty)
def as(alias: String): NamedExpression = Alias(expr, alias)()
def as(alias: Symbol): NamedExpression = Alias(expr, alias.name)()
}
Expand Down
4 changes: 2 additions & 2 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SortOrder.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,12 +36,12 @@ abstract sealed class NullOrdering {

case object Ascending extends SortDirection {
override def sql: String = "ASC"
override def defaultNullOrdering: NullOrdering = NullsFirst
override def defaultNullOrdering: NullOrdering = NullsLast
}

case object Descending extends SortDirection {
override def sql: String = "DESC"
override def defaultNullOrdering: NullOrdering = NullsLast
override def defaultNullOrdering: NullOrdering = NullsFirst
Copy link
Member

@HyukjinKwon HyukjinKwon Jul 15, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think this is a breaking change and workaround looks pretty easy. Can you check what other DBMSs do? If it's consistent with some other DBMSs, I think we shouldn't fix it and resolve the ticket as Won't Do

Copy link
Contributor Author

@shivusondur shivusondur Jul 15, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@HyukjinKwon
From the below link, spark is consistent with mysql, sqlserver
But inconsitent with DB2, Oracle, Postgresql
https://docs.mendix.com/refguide/null-ordering-behavior#3-overview-of-default-nulls-sort-order

image

Copy link
Member

@HyukjinKwon HyukjinKwon Jul 15, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think the current behaviour already makes sense. I wouldn't fix it. cc @dongjoon-hyun, @wangyum, @gatorsmile WDYT?

Copy link
Member

@dongjoon-hyun dongjoon-hyun Jul 15, 2019

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

+1 for @HyukjinKwon 's comment.

}

case object NullsFirst extends NullOrdering{
Expand Down
2 changes: 1 addition & 1 deletion ...st/src/test/scala/org/apache/spark/sql/catalyst/optimizer/RemoveRedundantSortsSuite.scala
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,7 @@ class RemoveRedundantSortsSuite extends PlanTest {
}

test("do not remove sort if the order is different") {
val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc_nullsFirst)
val orderedPlan = testRelation.select('a, 'b).orderBy('a.asc, 'b.desc_nullsLast)
val reorderedDifferently = orderedPlan.limit(2).select('a).orderBy('a.asc, 'b.desc)
val optimized = Optimize.execute(reorderedDifferently.analyze)
val correctAnswer = reorderedDifferently.analyze
Expand Down