Pulkit Sharma created HIVE-22487:
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Summary: Windowing functions (first_value and last_value) doesnot
ignore null values until non-null value is found
Key: HIVE-22487
URL: https://issues.apache.org/jira/browse/HIVE-22487
Project: Hive
Issue Type: Bug
Reporter: Pulkit Sharma
Windowing functions (first_value and last_value) does not ignore null values
until it encounters the first non-null value. If the non-null value for field
is found, it shows first_value/last_value as null until the non-null value for
field is found.
How to reproduce :
{code:java}
create table test_first_value(state string, seats int, name string);
insert into test_first_value values('CA', 16, null);
insert into test_first_value values('CA', 17, 'CA17');
insert into test_first_value values('CA', 18, 'CA18');
insert into test_first_value values('CA', 19, null);
insert into test_first_value values('CA', 20, null);
insert into test_first_value values('CA', 21, null);
select state, seats, name, first_value(name, true) over (PARTITION by state
order by seats desc ) from test_first_value;
Results :
CA 21 NULL NULL
CA 20 NULL NULL
CA 19 NULL NULL
CA 18 CA18 CA18
CA 17 CA17 CA18
CA 16 NULL CA18
{code}
In this case, col4 is first_value(name) with _ignore nulls_ as true but we
still got NULL in first three rows.
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