ygf11 opened a new issue, #5344:
URL: https://github.com/apache/arrow-datafusion/issues/5344
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
After #5264, we support rewriting more `where-exists` to join, but do not
add back the `Distinct`.
For query:
```sql
SELECT t1.t1_id
FROM t1
WHERE EXISTS(SELECT DISTINCT t2_int
FROM t2
WHERE t2.t2_id > t1.t1_id);
# current logical plan:
Projection: t1.t1_id
LeftSemi Join: Filter: t2.t2_id > t1.t1_id
TableScan: t1 projection=[t1_id]
Projection: t2.t2_id # DISTINCT is not added back
TableScan: t2 projection=[t2_id]
```
Although the execution result is correct, we should add back the `DISTINCT`.
In some cases, `DISTINCT` can filter a lot rows before join, we should let
`user` choose.
**Describe the solution you'd like**
Add back `Distinct` if the subquery is a `DISTINCT`.
**Describe alternatives you've considered**
A clear and concise description of any alternative solutions or features
you've considered.
**Additional context**
Add any other context or screenshots about the feature request here.
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