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https://issues.apache.org/jira/browse/DRILL-4449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15185043#comment-15185043
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Deneche A. Hakim commented on DRILL-4449:
-----------------------------------------
I was able to create a reproduction of the issue, in case it's later needed for
validation:
create a partitioned table:
{noformat}
CREATE TABLE dfs.tmp.t PARTITION BY(l_discount) AS SELECT * FROM
cp.`tpch/lineitem.parquet`;
{noformat}
The following query will give wrong results if the table has a metadata cache
file:
{noformat}
SELECT COUNT(*) FROM (
SELECT l_orderkey FROM dfs.tmp.t WHERE l_discount < 0.05
UNION ALL
SELECT l_orderkey FROM dfs.tmp.t WHERE l_discount > 0.02
);
{noformat}
> Wrong results when using metadata cache with specific set of queries
> --------------------------------------------------------------------
>
> Key: DRILL-4449
> URL: https://issues.apache.org/jira/browse/DRILL-4449
> Project: Apache Drill
> Issue Type: Bug
> Components: Storage - Parquet
> Affects Versions: 1.5.0
> Reporter: Deneche A. Hakim
> Assignee: Deneche A. Hakim
> Priority: Critical
> Fix For: 1.6.0
>
>
> We are still working on a reproduction but when we have a query similar to
> this one:
> {noformat}
> 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
> );
> {noformat}
> 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.
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