Nemon Lou created HIVE-24902:
--------------------------------
Summary: Incorrect result due to ReduceExpressionsRule
Key: HIVE-24902
URL: https://issues.apache.org/jira/browse/HIVE-24902
Project: Hive
Issue Type: Bug
Components: CBO
Affects Versions: 3.1.2, 4.0.0
Reporter: Nemon Lou
The following sql returns only one record (20210308)but we expect two(20210308
20210309).
{code:sql}
select * from (
select
case when b.a=1
then
cast
(from_unixtime(unix_timestamp(cast(20210309 as string),'yyyyMMdd') -
86400,'yyyyMMdd') as bigint)
else
20210309
end
as col
from
(select stack(2,1,2) as (a))
as b
) t
where t.col is not null;
{code}
After debuging, i find the ReduceExpressionsRule changes expression in the
wrong way.
Original expression:
{code:sql}
IS NOT NULL(CASE(=($0, 1),
CAST(FROM_UNIXTIME(-(UNIX_TIMESTAMP(CAST(_UTF-16LE'20210309'):VARCHAR(2147483647)
CHARACTER SET "UTF-16LE" COLLATE "ISO-8859-1$en_US$primary",
_UTF-16LE'yyyyMMdd'), CAST(86400):BIGINT), _UTF-16LE'yyyyMMdd')):BIGINT,
20210309))
{code}
After reducing expressions:
{code:sql}
CASE(=($0, 1), IS NOT
NULL(CAST(FROM_UNIXTIME(-(UNIX_TIMESTAMP(CAST(_UTF-16LE'20210309'):VARCHAR(2147483647)
CHARACTER SET "UTF-16LE" COLLATE "ISO-8859-1$en_US$primary",
_UTF-16LE'yyyyMMdd'), CAST(86400):BIGINT), _UTF-16LE'yyyyMMdd')):BIGINT), true)
{code}
The query plan in main branch:
{code:sql}
STAGE DEPENDENCIES:
Stage-0 is a root stage
STAGE PLANS:
Stage: Stage-0
Fetch Operator
limit: -1
Processor Tree:
TableScan
alias: _dummy_table
Row Limit Per Split: 1
Statistics: Num rows: 1 Data size: 10 Basic stats: COMPLETE Column
stats: COMPLETE
Select Operator
expressions: 2 (type: int), 1 (type: int), 2 (type: int)
outputColumnNames: _col0, _col1, _col2
Statistics: Num rows: 1 Data size: 12 Basic stats: COMPLETE Column
stats: COMPLETE
UDTF Operator
Statistics: Num rows: 1 Data size: 12 Basic stats: COMPLETE
Column stats: COMPLETE
function name: stack
Filter Operator
predicate: COALESCE((col0 = 1),false) (type: boolean)
Statistics: Num rows: 1 Data size: 12 Basic stats: COMPLETE
Column stats: COMPLETE
Select Operator
expressions: CASE WHEN ((col0 = 1)) THEN (20210308L) ELSE
(20210309L) END (type: bigint)
outputColumnNames: _col0
Statistics: Num rows: 1 Data size: 8 Basic stats: COMPLETE
Column stats: COMPLETE
ListSink
Time taken: 0.155 seconds, Fetched: 28 row(s)
{code}
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