Not the answer you need?
Register and ask your own question!
Many Forum changes were implemented on Tue 22 Sep. Read about new Ranks, Scoring, and Reactions.
Email [email protected] for any comments or concerns.

Strange behaviour on partitioned table (Percona Server 5.5.36)

Sam_ButlerSam_Butler EntrantInactive User Role Beginner
This one's really got me. Maybe it's a bug. Ideas anyone? See below...

We have a table with the following partition scheme (example names and values):
PARTITION BY LIST COLUMNS(`owner`)
SUBPARTITION BY HASH(CASE WHEN (`foo`+`bar`) < 1 THEN 0 ELSE 1 END)
SUBPARTITIONS 2 (
    PARTITION p0 VALUES IN('A','B','C','D','E','F','G'),
    PARTITION p1 VALUES IN('H'),
    PARTITION p2 VALUES IN('I','J'),
    PARTITION p3 VALUES IN('K')
);

N.B. the A,B,C, etc. values above are only examples. The real table has strings that represent the owner of the row. There are over 3m rows.

We should end up with a partition that has all the foo+bar = 0 values owned by A through G as the first subpartition of partition p0.

We get the following output from :
+----------+----------+
| owner    | COUNT(*) |
+----------+----------+
| H        |  2077675 |
| B        |   138243 |
| I        |    13333 |
| C        |    26507 |
| A        |   806889 |
| K        |      134 |
| E        |    38165 |
| D        |    14118 |
+----------+----------+

There are no values for F, G or J.

Now when I run , I get zero.

If I change the list to

I've tested this on 5.6 on another server with a subset of the data, and it is fine, with the additional feature of selecting directly from p0, etc.

Anyone ever seen anything like this? Am I missing something? Let me know if you want to know any variables.

--
Sam

Comments

  • Sam_ButlerSam_Butler Entrant Inactive User Role Beginner
    We had to upgrade to 5.6, and the issue was resolved as I suspected it would be. This would appear to have been a bug, though it would be complex to reproduce so I have no way of knowing if perhaps it was a data corruption error.
Sign In or Register to comment.

MySQL, InnoDB, MariaDB and MongoDB are trademarks of their respective owners.
Copyright ©2005 - 2020 Percona LLC. All rights reserved.