[MCOL-4612] A subquery with a union for DECIMAL and BIGINT returns zeros Created: 2021-03-16  Updated: 2021-05-24  Resolved: 2021-05-24

Status: Closed
Project: MariaDB ColumnStore
Component/s: ExeMgr, PrimProc
Affects Version/s: 6.1.1
Fix Version/s: 6.1.1

Type: Bug Priority: Blocker
Reporter: Alexander Barkov Assignee: Daniel Lee (Inactive)
Resolution: Fixed Votes: 0
Labels: transient_regression

Issue Links:
Blocks
blocks MCOL-4613 Garbage result of a union between hug... Closed
Relates
relates to MCOL-4361 Replace pow(10.0, (double)scale) expr... Closed
relates to MCOL-641 Full DECIMAL support in ColumnStore Closed
relates to MCOL-4700 Wrong result of a UNION for INT and I... Closed
Sub-Tasks:
Key
 Summary
 Type
 Status
 Assignee
MCOL-4706 Additional test needed Sub-Task Closed Daniel Lee  
Sprint: 2021-8

 Description   

The problem does not seem to be repeatable in 5.x.

DROP TABLE IF EXISTS t1;
 
CREATE TABLE t1 (a DECIMAL(17,1), b BIGINT) ENGINE=ColumnStore;
 
INSERT INTO t1 VALUES (1, 1);
 
INSERT INTO t1 VALUES (9999999999999999, 99999999999999999);
 
SELECT * FROM (SELECT a FROM t1 UNION SELECT b FROM t1) tu;


+------+
 
| a    |
 
+------+
 
|  0.0 |
 
|  0.0 |
 
|  0.0 |
 
+------+


SELECT * FROM (SELECT a FROM t1 UNION ALL SELECT b FROM t1) tu;


+------+
 
| a    |
 
+------+
 
|  0.0 |
 
|  0.0 |
 
|  0.0 |
 
|  0.0 |
 
+------+

Note, without the subquery it works as expected:

SELECT a FROM t1 UNION SELECT b FROM t1;


+---------------------+
 
| a                   |
 
+---------------------+
 
|                 1.0 |
 
|  9999999999999999.0 |
 
| 99999999999999999.0 |
 
+---------------------+


SELECT a FROM t1 UNION ALL SELECT b FROM t1;


+---------------------+
 
| a                   |
 
+---------------------+
 
|                 1.0 |
 
|  9999999999999999.0 |
 
|                 1.0 |
 
| 99999999999999999.0 |
 
+---------------------+



 Comments   
Comment by Gagan Goel (Inactive) [ 2021-04-29 ]

For QA: Queries to confirm the issue and verify the fix works are in the issue description.

Comment by Daniel Lee (Inactive) [ 2021-05-24 ]

Build verified: 6.1.1 (Drone #2394)

MariaDB [mytest]> SELECT * FROM (SELECT a FROM t1 UNION SELECT b FROM t1) tu;
 
+---------------------+
 
| a                   |
 
+---------------------+
 
|                 1.0 |
 
| 99999999999999999.0 |
 
|  9999999999999999.0 |
 
+---------------------+
 
3 rows in set (0.096 sec)
 
 
 
MariaDB [mytest]> SELECT * FROM (SELECT a FROM t1 UNION ALL SELECT b FROM t1) tu;
 
+---------------------+
 
| a                   |
 
+---------------------+
 
|                 1.0 |
 
| 99999999999999999.0 |
 
|                 1.0 |
 
|  9999999999999999.0 |
 
+---------------------+
 
4 rows in set (0.027 sec)

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