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[GitHub] [spark] ConeyLiu opened a new pull request, #37565: [SPARK-40137][SQL] Combines limits after projection
ConeyLiu opened a new pull request, #37565:
URL: https://github.com/apache/spark/pull/37565
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### What changes were proposed in this pull request?
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Combine the limits after projection.
### Why are the changes needed?
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1. If you propose a new API, clarify the use case for a new API.
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`Dataset.show` will add extra `Limit` and `Projection` on top of the given logical plan. If the `Dataset` is already a limit job, this will introduce an extra shuffle phase. So we should combine the limit after projection.
For example:
```scala
spark.sql("select * from spark.store_sales limit 10").show()
```
Before:
```
== Physical Plan ==
AdaptiveSparkPlan (12)
+- == Final Plan ==
* Project (7)
+- * GlobalLimit (6)
+- ShuffleQueryStage (5), Statistics(sizeInBytes=185.6 KiB, rowCount=990)
+- Exchange (4)
+- * LocalLimit (3)
+- * ColumnarToRow (2)
+- Scan parquet spark_catalog.spark.store_sales (1)
+- == Initial Plan ==
Project (11)
+- GlobalLimit (10)
+- Exchange (9)
+- LocalLimit (8)
+- Scan parquet spark_catalog.spark.store_sales (1)
```
After:
```
== Physical Plan ==
CollectLimit (4)
+- * Project (3)
+- * ColumnarToRow (2)
+- Scan parquet spark_catalog.spark.store_sales (1)
```
### Does this PR introduce _any_ user-facing change?
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Note that it means *any* user-facing change including all aspects such as the documentation fix.
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No
### How was this patch tested?
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UT and local test.
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[GitHub] [spark] ConeyLiu commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
ConeyLiu commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r953895575
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -769,6 +783,13 @@ object LimitPushDown extends Rule[LogicalPlan] {
// Push down local limit 1 if join type is LeftSemiOrAnti and join condition is empty.
case j @ Join(_, right, LeftSemiOrAnti(_), None, _) if !right.maxRows.exists(_ <= 1) =>
j.copy(right = maybePushLocalLimit(Literal(1, IntegerType), right))
+
+ case GlobalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, Limit(l, child))
Review Comment:
Thanks, @wangyum. This is a really much better solution. The failed python ut should be fixed by this update.
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r952105713
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -1994,6 +1994,13 @@ object EliminateLimits extends Rule[LogicalPlan] {
LocalLimit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
case Limit(le, Limit(ne, grandChild)) =>
Limit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
+
+ case GlobalLimit(l, Project(projectList, child)) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, Project(projectList, child)) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, Project(projectList, child)) =>
+ Project(projectList, Limit(l, child))
Review Comment:
Could you move these changes to `LimitPushDown`?
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[GitHub] [spark] ConeyLiu commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
ConeyLiu commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r954873986
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -769,6 +769,16 @@ object LimitPushDown extends Rule[LogicalPlan] {
// Push down local limit 1 if join type is LeftSemiOrAnti and join condition is empty.
case j @ Join(_, right, LeftSemiOrAnti(_), None, _) if !right.maxRows.exists(_ <= 1) =>
j.copy(right = maybePushLocalLimit(Literal(1, IntegerType), right))
+
+ case GlobalLimit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, Limit(l, child))
Review Comment:
Yes, like this.
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[GitHub] [spark] ConeyLiu commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
ConeyLiu commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r949857547
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -1994,6 +1994,13 @@ object EliminateLimits extends Rule[LogicalPlan] {
LocalLimit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
case Limit(le, Limit(ne, grandChild)) =>
Limit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
+
+ case Project(projectList, Limit(l, child)) =>
Review Comment:
Thanks @wangyum for your time. What about:
```scala
case Limit(l, Project(projectList, child)) =>
Project(projectList, Limit(l, child))
```
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[GitHub] [spark] github-actions[bot] closed pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
github-actions[bot] closed pull request #37565: [SPARK-40137][SQL] Combines limits after projection
URL: https://github.com/apache/spark/pull/37565
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r949749115
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -1994,6 +1994,13 @@ object EliminateLimits extends Rule[LogicalPlan] {
LocalLimit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
case Limit(le, Limit(ne, grandChild)) =>
Limit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
+
+ case Project(projectList, Limit(l, child)) =>
Review Comment:
`projectList` may contain very heavy UDFs. This change may increase `Project` evaluation cost.
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r953811144
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -769,6 +783,13 @@ object LimitPushDown extends Rule[LogicalPlan] {
// Push down local limit 1 if join type is LeftSemiOrAnti and join condition is empty.
case j @ Join(_, right, LeftSemiOrAnti(_), None, _) if !right.maxRows.exists(_ <= 1) =>
j.copy(right = maybePushLocalLimit(Literal(1, IntegerType), right))
+
+ case GlobalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, Limit(l, child))
Review Comment:
How about?
```scala
case LocalLimit(l, p @ Project(projectList, child))
if child.outputSet.subsetOf(p.references) =>
Project(projectList, LocalLimit(l, child))
```
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r953811144
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -769,6 +783,13 @@ object LimitPushDown extends Rule[LogicalPlan] {
// Push down local limit 1 if join type is LeftSemiOrAnti and join condition is empty.
case j @ Join(_, right, LeftSemiOrAnti(_), None, _) if !right.maxRows.exists(_ <= 1) =>
j.copy(right = maybePushLocalLimit(Literal(1, IntegerType), right))
+
+ case GlobalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, proj @ Project(projectList, child)) if canPushLimitThroughProject(proj) =>
+ Project(projectList, Limit(l, child))
Review Comment:
How about?
```scala
case GlobalLimit(l, p @ Project(projectList, child))
if child.outputSet.subsetOf(p.references) =>
Project(projectList, GlobalLimit(l, child))
case LocalLimit(l, p @ Project(projectList, child))
if child.outputSet.subsetOf(p.references) =>
Project(projectList, LocalLimit(l, child))
case Limit(l, p @ Project(projectList, child))
if child.outputSet.subsetOf(p.references) =>
Project(projectList, Limit(l, child))
```
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[GitHub] [spark] AmplabJenkins commented on pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
AmplabJenkins commented on PR #37565:
URL: https://github.com/apache/spark/pull/37565#issuecomment-1220442182
Can one of the admins verify this patch?
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r954475934
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -769,6 +769,16 @@ object LimitPushDown extends Rule[LogicalPlan] {
// Push down local limit 1 if join type is LeftSemiOrAnti and join condition is empty.
case j @ Join(_, right, LeftSemiOrAnti(_), None, _) if !right.maxRows.exists(_ <= 1) =>
j.copy(right = maybePushLocalLimit(Literal(1, IntegerType), right))
+
+ case GlobalLimit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, GlobalLimit(l, child))
+ case LocalLimit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, LocalLimit(l, child))
+ case Limit(l, p @ Project(projectList, child))
+ if child.outputSet.subsetOf(p.references) =>
+ Project(projectList, Limit(l, child))
Review Comment:
So we are trying to optimize this case?
```scala
spark.sql("select *,ss_sold_time_sk + 3 from (select *, ss_sold_time_sk + 2 from (select *, ss_sold_time_sk + 1 from store_sales limit 10) limit 9) limit 8").show()
```
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[GitHub] [spark] wangyum commented on a diff in pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
wangyum commented on code in PR #37565:
URL: https://github.com/apache/spark/pull/37565#discussion_r950142433
##########
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala:
##########
@@ -1994,6 +1994,13 @@ object EliminateLimits extends Rule[LogicalPlan] {
LocalLimit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
case Limit(le, Limit(ne, grandChild)) =>
Limit(Literal(Least(Seq(ne, le)).eval().asInstanceOf[Int]), grandChild)
+
+ case Project(projectList, Limit(l, child)) =>
Review Comment:
+1.
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[GitHub] [spark] github-actions[bot] commented on pull request #37565: [SPARK-40137][SQL] Combines limits after projection
Posted by GitBox <gi...@apache.org>.
github-actions[bot] commented on PR #37565:
URL: https://github.com/apache/spark/pull/37565#issuecomment-1336285255
We're closing this PR because it hasn't been updated in a while. This isn't a judgement on the merit of the PR in any way. It's just a way of keeping the PR queue manageable.
If you'd like to revive this PR, please reopen it and ask a committer to remove the Stale tag!
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