Skip to content

[Bug Fix]: Deem hash repartition unnecessary when input and output has 1 partition #10095

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

Merged
merged 2 commits into from
Apr 16, 2024
Merged

[Bug Fix]: Deem hash repartition unnecessary when input and output has 1 partition #10095

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
d145880
Add input partition number check
mustafasrepo Apr 16, 2024
e614993
Minor changes
mustafasrepo Apr 16, 2024
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
3 changes: 2 additions & 1 deletion datafusion/core/src/physical_optimizer/enforce_distribution.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -875,7 +875,8 @@ fn add_hash_on_top(
n_target: usize,
) -> Result<DistributionContext> {
// Early return if hash repartition is unnecessary
if n_target == 1 {
// `RepartitionExec: partitioning=Hash([...], 1), input_partitions=1` is unnecessary.
if n_target == 1 && input.plan.output_partitioning().partition_count() == 1 {
return Ok(input);
}

Expand Down
101 changes: 101 additions & 0 deletions datafusion/sqllogictest/test_files/joins.slt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3587,3 +3587,104 @@ SELECT 1 FROM join_partitioned_table JOIN (SELECT c1 AS id1 FROM join_partitione
1
1
1


statement ok
set datafusion.explain.logical_plan_only = false;

query TT
EXPLAIN SELECT * FROM (
SELECT 1 as c, 2 as d
UNION ALL
SELECT 1 as c, 3 AS d
) as a FULL JOIN (SELECT 1 as e, 3 AS f) AS rhs ON a.c=rhs.e;
----
logical_plan
01)Projection: a.c, a.d, rhs.e, rhs.f
02)--Full Join: a.c = rhs.e
03)----SubqueryAlias: a
04)------Union
05)--------Projection: Int64(1) AS c, Int64(2) AS d
06)----------EmptyRelation
07)--------Projection: Int64(1) AS c, Int64(3) AS d
08)----------EmptyRelation
09)----SubqueryAlias: rhs
10)------Projection: Int64(1) AS e, Int64(3) AS f
11)--------EmptyRelation
physical_plan
01)ProjectionExec: expr=[c@2 as c, d@3 as d, e@0 as e, f@1 as f]
02)--CoalesceBatchesExec: target_batch_size=2
03)----HashJoinExec: mode=Partitioned, join_type=Full, on=[(e@0, c@0)]
04)------CoalesceBatchesExec: target_batch_size=2
05)--------RepartitionExec: partitioning=Hash([e@0], 2), input_partitions=1
06)----------ProjectionExec: expr=[1 as e, 3 as f]
07)------------PlaceholderRowExec
08)------CoalesceBatchesExec: target_batch_size=2
09)--------RepartitionExec: partitioning=Hash([c@0], 2), input_partitions=2
10)----------UnionExec
11)------------ProjectionExec: expr=[1 as c, 2 as d]
12)--------------PlaceholderRowExec
13)------------ProjectionExec: expr=[1 as c, 3 as d]
14)--------------PlaceholderRowExec

query IIII
SELECT * FROM (
SELECT 1 as c, 2 as d
UNION ALL
SELECT 1 as c, 3 AS d
) as a FULL JOIN (SELECT 1 as e, 3 AS f) AS rhs ON a.c=rhs.e;
----
1 2 1 3
1 3 1 3

statement ok
set datafusion.execution.target_partitions = 1;

query TT
EXPLAIN SELECT * FROM (
SELECT 1 as c, 2 as d
UNION ALL
SELECT 1 as c, 3 AS d
) as a FULL JOIN (SELECT 1 as e, 3 AS f) AS rhs ON a.c=rhs.e;
----
logical_plan
01)Projection: a.c, a.d, rhs.e, rhs.f
02)--Full Join: a.c = rhs.e
03)----SubqueryAlias: a
04)------Union
05)--------Projection: Int64(1) AS c, Int64(2) AS d
06)----------EmptyRelation
07)--------Projection: Int64(1) AS c, Int64(3) AS d
08)----------EmptyRelation
09)----SubqueryAlias: rhs
10)------Projection: Int64(1) AS e, Int64(3) AS f
11)--------EmptyRelation
physical_plan
01)ProjectionExec: expr=[c@2 as c, d@3 as d, e@0 as e, f@1 as f]
02)--CoalesceBatchesExec: target_batch_size=2
03)----HashJoinExec: mode=Partitioned, join_type=Full, on=[(e@0, c@0)]
04)------ProjectionExec: expr=[1 as e, 3 as f]
05)--------PlaceholderRowExec
06)------CoalesceBatchesExec: target_batch_size=2
07)--------RepartitionExec: partitioning=Hash([c@0], 1), input_partitions=2
08)----------UnionExec
09)------------ProjectionExec: expr=[1 as c, 2 as d]
10)--------------PlaceholderRowExec
11)------------ProjectionExec: expr=[1 as c, 3 as d]
12)--------------PlaceholderRowExec

query IIII
Copy link
Contributor

Choose a reason for hiding this comment

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

I think this query is non determisitic and fails sometimes on CI as it doesn't have an ORDER BY and isn't annotated with rowsort. Here is a PR to fix that: #10120

SELECT * FROM (
SELECT 1 as c, 2 as d
UNION ALL
SELECT 1 as c, 3 AS d
) as a FULL JOIN (SELECT 1 as e, 3 AS f) AS rhs ON a.c=rhs.e;
----
1 2 1 3
1 3 1 3

statement ok
set datafusion.explain.logical_plan_only = true;

statement ok
set datafusion.execution.target_partitions = 2;