HIVE-23954 count(*) with count(distinct) gives wrong results with hive.optimize.countdistinct=true

[EugeneChung]

What changes were proposed in this pull request?

It skips the reducer deduplication for the case that the usages of count function for all and distinct are mixed.

Why are the changes needed?

select count(*), count(distinct mid) from db1.table1 where partitioned_column = '...' shows the wrong results especially for count(*).

Does this PR introduce any user-facing change?

No

How was this patch tested?

I've tested with the same query like select count(*), count(distinct mid) from db1.table1 where partitioned_column = '...' over the same data set. My patch shows the correct result with hive.optimize.countdistinct=true as the one of hive.optimize.countdistinct=false.

[EugeneChung]

It seems the error of init-metastore is not related with my patch.

[2020-08-20T11:29:42.268Z] Status: Downloaded newer image for postgres:latest

[2020-08-20T11:31:48.820Z] 3a1dc3a0b3a75eaf727731e23f9967bbc6007831481878432cad7c8354e0c922

[2020-08-20T11:31:48.821Z] waiting for postgres to be available...

[2020-08-20T11:31:48.821Z] psql: FATAL:  the database system is starting up

[2020-08-20T11:31:48.821Z] ok

[2020-08-20T11:31:48.821Z] NOTICE:  database "ms_hive_precommit_pr_1414_1_wqrcz_rrtk5_5s4x9" does not exist, skipping

[2020-08-20T11:31:48.821Z] DROP DATABASE

[2020-08-20T11:31:48.821Z] ERROR:  role "hive" does not exist

http://ci.hive.apache.org/blue/organizations/jenkins/hive-precommit/detail/PR-1414/1/tests shows all tests were passed.

[github-actions]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.
Feel free to reach out on the dev@hive.apache.org list if the patch is in need of reviews.