nuno-faria commented on PR #17197:
URL: https://github.com/apache/datafusion/pull/17197#issuecomment-3191090428
Thanks @adriangb for looking into it.
I found some issues with the fix.
1. It appears to be causing a regression with the regular dynamic filter
pushdown. Now more rows are being returned than what is supposed to. For
example:
```sql
copy (select i as k from generate_series(1, 10000000) as t(i)) to
't1.parquet';
copy (select i as k, i as v from generate_series(1, 10000000) as t(i)) to
't2.parquet';
create external table t1 stored as parquet location 't1.parquet';
create external table t2 stored as parquet location 't2.parquet';
explain analyze select *
from t1
join t2 on t1.k = t2.k
where v = 1;
-- in each run, the number of returned rows by t1 is different
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=6854272
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=8951424
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=7902848
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=8951424
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=7902848
```
On main, the number of rows returned by t1 is the minimum expected:
```sql
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=20480
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=20480
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=20480
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=20480
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 1 ]
output_rows=20480
```
2. With partitioned joins, the dynamic filter is always `true`, while I
think it should be the minimum/maximum of all partial filters. For example:
```sql
explain analyze select *
from t1
join t2 on t1.k = t2.k
where v = 1 or v = 2;
-- all rows are returned
DataSourceExec t1.parquet predicate=DynamicFilterPhysicalExpr [ true ]
output_rows=10000000
```
I think in this case it should be `DynamicFilterPhysicalExpr [ k@0 >= 1 AND
k@0 <= 2 ]`.
However, if we had `v=1 or v=10000000` the filter in this case would be `[
k@0 >= 1 AND k@0 <= 10000000 ]`, which would also return all rows. Wouldn't it
be feasible to build a filter by combining the different partition expressions
with OR? Like so: `[ (k@0 >= 1 AND k@0 <= 1) OR (k@0 >= 10000000 AND k@0 <=
10000000) ]`.
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