[DRILL-4449] Wrong results when using metadata cache with specific set of queries

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.5.0
• Fix Version/s: 1.6.0
• Component/s: Storage - Parquet
• Assignee: Abdel Hakim Deneche
• Reporter: Abdel Hakim Deneche
• Reviewer: Rahul Kumar Challapalli
• Created: 26/Feb/16 21:40
• Updated: 08/Apr/16 23:07
• Resolved: 04/Mar/16 23:42

Description

We are still working on a reproduction but when we have a query similar to this one:

with q1 as (
select a.field
from `table` a
where <some condition that causes the table to be pruned>
group by a.field
having ...
)
, q2 as (
select a.field
from `table` a
where <some other pruning condition>
group by a.field
)
select * from (
select count(*) as cnt from q1
union all
select count(*) as cnt from q2
);

The table is partitioned and both sub queries will force a parquet pruning on the table. Because we share the parquet metadata object in ParquetGroupScan, the second query end up being "over pruned" and we get wrong results.

The plan doesn't show the problem.