Eugene Chung created HIVE-23954:
-----------------------------------
Summary: count(*) with count(distinct) gives wrong results with
hive.optimize.countdistinct=true
Key: HIVE-23954
URL: https://issues.apache.org/jira/browse/HIVE-23954
Project: Hive
Issue Type: Bug
Components: Logical Optimizer
Affects Versions: 3.1.0, 3.0.0
Reporter: Eugene Chung
select count(*), count(distinct mycol) from db1.table1 where partitioned_column
= '...'
is not working properly when hive.optimize.countdistinct is true. By default,
it's true for all 3.x versions.
In the two plans below, the aggregations part in the Output of Group By
Operator of Map 1 are different.
- hive.optimize.countdistinct=false
{code:java}
+----------------------------------------------------+
| Explain |
+----------------------------------------------------+
| Plan optimized by CBO. |
| |
| Vertex dependency in root stage |
| Reducer 2 <- Map 1 (SIMPLE_EDGE) |
| |
| Stage-0 |
| Fetch Operator |
| limit:-1 |
| Stage-1 |
| Reducer 2 |
| File Output Operator [FS_7] |
| Group By Operator [GBY_5] (rows=1 width=24) |
|
Output:["_col0","_col1"],aggregations:["count(VALUE._col0)","count(DISTINCT
KEY._col0:0._col0)"] |
| <-Map 1 [SIMPLE_EDGE] |
| SHUFFLE [RS_4] |
| Group By Operator [GBY_3] (rows=343640771 width=4160) |
|
Output:["_col0","_col1","_col2"],aggregations:["count()","count(DISTINCT
mid)"],keys:mid |
| Select Operator [SEL_2] (rows=343640771 width=4160) |
| Output:["mid"] |
| TableScan [TS_0] (rows=343640771 width=4160) |
| db1@table1,table1,Tbl:COMPLETE,Col:NONE,Output:["mid"] |
| |
+----------------------------------------------------+{code}
- hive.optimize.countdistinct=true
{code:java}
+----------------------------------------------------+
| Explain |
+----------------------------------------------------+
| Plan optimized by CBO. |
| |
| Vertex dependency in root stage |
| Reducer 2 <- Map 1 (SIMPLE_EDGE) |
| |
| Stage-0 |
| Fetch Operator |
| limit:-1 |
| Stage-1 |
| Reducer 2 |
| File Output Operator [FS_7] |
| Group By Operator [GBY_14] (rows=1 width=16) |
|
Output:["_col0","_col1"],aggregations:["count(_col1)","count(_col0)"] |
| Group By Operator [GBY_11] (rows=343640771 width=4160) |
|
Output:["_col0","_col1"],aggregations:["count(VALUE._col0)"],keys:KEY._col0 |
| <-Map 1 [SIMPLE_EDGE] |
| SHUFFLE [RS_10] |
| PartitionCols:_col0 |
| Group By Operator [GBY_9] (rows=343640771 width=4160) |
| Output:["_col0","_col1"],aggregations:["count()"],keys:mid |
| Select Operator [SEL_2] (rows=343640771 width=4160) |
| Output:["mid"] |
| TableScan [TS_0] (rows=343640771 width=4160) |
| db1@table1,table1,Tbl:COMPLETE,Col:NONE,Output:["mid"] |
| |
+----------------------------------------------------+
{code}
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