Aman Sinha created DRILL-1362:
---------------------------------
Summary: Count(nullable-column) is incorrectly pushed into group
scan operator
Key: DRILL-1362
URL: https://issues.apache.org/jira/browse/DRILL-1362
Project: Apache Drill
Issue Type: Bug
Components: Execution - Operators
Affects Versions: 0.4.0
Reporter: Aman Sinha
The following query on TPC-DS table web_returns produces wrong result because
the aggregate count(wr_return_quantity) gets pushed into the parquet group scan
operator even though wr_return_quantity is nullable and apparently the parquet
metadata does not have stats on nullable column.
0: jdbc:drill:zk=local> select count(wr_return_quantity) from web_returns;
+------------+
| EXPR$0 |
+------------+
| 71763 |
+------------+
0: jdbc:drill:zk=local> explain plan for select count(wr_return_quantity) from
web_returns;
{code:sql}
+------------+------------+
| text | json |
+------------+------------+
| 00-00 Screen
00-01 Project(EXPR$0=[$0])
00-02
Scan(groupscan=[org.apache.drill.exec.store.pojo.PojoRecordReader@e4acaad])
{code}
For reference, here are the correct results:
tpcds=# select count(wr_return_quantity) from web_returns;
count
-------
68616
(1 row)
tpcds=# select count(*) from web_returns;
count
-------
71763
(1 row)
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