LakshSingla opened a new pull request, #16872:
URL: https://github.com/apache/druid/pull/16872
### Description
(Updating with a test case on the UT)
Consider the following query
```sql
select
t1.countryName,
t2.countryName,
t1.code,
t2.code
from wikiticker t1 left join wikiticker t2
on t1.countryName = t2.countryName and t1.code = t2.code
where
t1.countryName in ('Japan', 'Peru')
and (t1.code in ('J', 'P') or t1.code is null)
and t2.countryName in ('Japan', 'Peru')
and (t2.code in ('J', 'P') or t2.code is null)
```
on the table
| countryName | code |
|--------|--------|
| Japan | J |
| Peru | null |
The query returns the following answer
| t1.countryName | t1.code | t2.countryName | t2.code |
|--------|--------|--------|--------|
| Japan | J | Japan | null |
| Peru | null | null | null |
However the filter `t2.countryName in ('Japan', 'Peru')` doesn't hold true
for the second row that is returned. This happens because the filter on the RHS
is rewritten to a filter on the LHS, which matches for both rows. The join
returns `(Peru, null, null, null)` for the second row since that row doesn't
join because of `(t1.code = t2.code)`. However, the rewritten filter is lost
and we return an answer for which the filter doesn't hold.
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<hr>
##### Key changed/added classes in this PR
* `MyFoo`
* `OurBar`
* `TheirBaz`
<hr>
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This PR has:
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- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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