nuno-faria opened a new pull request, #16716:
URL: https://github.com/apache/datafusion/pull/16716
## Which issue does this PR close?
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N/A.
## Rationale for this change
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Why are you proposing this change? If this is already explained clearly in
the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand your
changes and offer better suggestions for fixes.
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When executing hash joins, the build side is first built from the left
relation and then the right relation is joined with it. However, when the build
side has no rows, the join operation can be mostly skipped, improving
performance.
For example, here is a simple anti join query, where `t1` has 100M rows and
`t2` has none:
```sql
SELECT *
FROM t1
LEFT ANTI JOIN t2 on t1.k = t2.k
```
Here is the hash join operator in the current implementation:
```txt
HashJoinExec: mode=Partitioned, join_type=RightAnti, on=[(k@0, k@0)],
metrics=[
output_rows=100000000,
build_input_batches=0,
build_input_rows=0,
input_batches=11733,
input_rows=100000000,
output_batches=23403,
build_mem_used=876,
build_time=2.8693ms,
join_time=216.251396302s
]
```
And here is the optimized hash join operation:
```txt
HashJoinExec: mode=Partitioned, join_type=RightAnti, on=[(k@0, k@0)],
metrics=[
output_rows=100000000,
build_input_batches=0,
build_input_rows=0,
input_batches=11733,
input_rows=100000000,
output_batches=11733,
build_mem_used=876,
build_time=2.4597ms,
join_time=36.038306ms
]
```
The total join time went from 216s to just 36ms.
## What changes are included in this PR?
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sometimes worth providing a summary of the individual changes in this PR.
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- Changed `process_probe_batch` in `physical-plan/hash_join.rs` to optimized
the join.
- Added multiple sqllogictests.
## Are these changes tested?
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2. Serve as another way to document the expected behavior of the code
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Yes.
## Are there any user-facing changes?
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updated before approving the PR.
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No.
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