[jira] [Created] (HIVE-19097) related equals and in operators may result in a high inaccurate stat estimation

[Zoltan Haindrich (JIRA)]

Zoltan Haindrich created HIVE-19097:
---------------------------------------

             Summary: related equals and in operators may result in a high 
inaccurate stat estimation
                 Key: HIVE-19097
                 URL: https://issues.apache.org/jira/browse/HIVE-19097
             Project: Hive
          Issue Type: Bug
            Reporter: Zoltan Haindrich


tpcds#74 is optimized in a way that for date_dim the condition contains IN and 
= for the same column

{code}
|             Map Operator Tree:                     |
|                 TableScan                          |
|                   alias: date_dim                  |
|                   filterExpr: (((d_year) IN (2001, 2002) and (d_year = 2002) 
and d_date_sk is not null) or ((d_year) IN (2001, 2002) and (d_year = 2001) and 
d_date_sk is not null)) (type: boolean) |
|                   Statistics: Num rows: 73049 Data size: 876588 Basic stats: 
COMPLETE Column stats: COMPLETE |
|                   Filter Operator                  |
|                     predicate: ((d_year) IN (2001, 2002) and (d_year = 2002) 
and d_date_sk is not null) (type: boolean) |
|                     Statistics: Num rows: 4 Data size: 48 Basic stats: 
COMPLETE Column stats: COMPLETE |
{code}

for separate {{IN}} and {{=}} the estimation is very good; but if both are 
present it becomes (very) underestimated.

{code}

set hive.query.results.cache.enabled=false;

drop table if exists t1;
drop table if exists t8;

create table t1 (a integer,b integer);
create table t8 like t1;

insert into t1 values (1,1),(2,2),(3,3),(4,4),(5,5);

insert into t8
select * from t1 union all select * from t1 union all select * from t1 union 
all select * from t1 union all
select * from t1 union all select * from t1 union all select * from t1 union 
all select * from t1
;

analyze table t1 compute statistics for columns;
analyze table t8 compute statistics for columns;

explain analyze select sum(a) from t8 where b in (2,3) group by b;
explain analyze select sum(a) from t8 where b=2 group by b;

explain analyze select sum(a) from t1 where b in (2,3) and b=2 group by b;
explain analyze select sum(a) from t8 where b in (2,3) and b=2 group by b;

{code}



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