[MCOL-4455] "SELECT DISTINCT col FROM table LIMIT O,N" ignores offset Created: 2020-12-16  Updated: 2021-01-25  Resolved: 2021-01-25

Status: Closed
Project: MariaDB ColumnStore
Component/s: ExeMgr
Affects Version/s: None
Fix Version/s: 5.5.2

Type: Bug Priority: Major
Reporter: Alexey Antipovsky (Inactive) Assignee: Daniel Lee (Inactive)
Resolution: Fixed Votes: 0
Labels: None

Issue Links:
Problem/Incident
causes MCOL-4505 Regression: DISTINCT with sub query g... Closed
Relates
relates to MCOL-4453 CREATE TABLE t2 AS SELECT..LIMIT 0 er... Closed

 Description    

DROP TABLE IF EXISTS a;
 
CREATE TABLE a (a INT) ENGINE=Columnstore;
 
INSERT INTO a VALUES (1), (1), (2), (3);
 
SELECT DISTINCT a FROM a LIMIT 2;
 
/*
 
+------+
 
| a    |
 
+------+
 
|    1 |
 
|    2 |
 
+------+
 
*/
 
SELECT DISTINCT a FROM a LIMIT 2,2;
 
/*
 
+------+
 
| a    |
 
+------+
 
|    1 |
 
|    2 |
 
+------+
 
Expected:
 
+------+
 
| a    |
 
+------+
 
|    3 |
 
+------+
 
*/
 
SELECT DISTINCT a FROM a ORDER BY 1 LIMIT 2,2;
 
/*
 
+------+
 
| a    |
 
+------+
 
|    3 |
 
+------+
 
*/



 Comments   
Comment by Daniel Lee (Inactive) [ 2021-01-25 ]

Build verified: 5.5.2 (b1552), develop b1546
The fixed also checked into the develop branch

Comment by Daniel Lee (Inactive) [ 2021-01-25 ]

MariaDB [mytest]> DROP TABLE IF EXISTS a;
Query OK, 0 rows affected (0.150 sec)

MariaDB [mytest]> CREATE TABLE a (a INT) ENGINE=Columnstore;
Query OK, 0 rows affected (0.128 sec)

MariaDB [mytest]> INSERT INTO a VALUES (1), (1), (2), (3);
Query OK, 4 rows affected (0.201 sec)
Records: 4 Duplicates: 0 Warnings: 0

MariaDB [mytest]> SELECT DISTINCT a FROM a LIMIT 2;
------

a

------

1
2

------
2 rows in set (0.518 sec)

MariaDB [mytest]> SELECT DISTINCT a FROM a LIMIT 2,2;
------

a

------

3

------
1 row in set (0.041 sec)

MariaDB [mytest]> SELECT DISTINCT a FROM a ORDER BY 1 LIMIT 2,2;
------

a

------

3

------
1 row in set (0.040 sec)

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