Bug #31638 very high load instead error ?
Submitted: 16 Oct 2007 14:02 Modified: 16 Oct 2007 20:47
Reporter: Tordjman Yohan Email Updates:
Status: Not a Bug Impact on me:
None 
Category:MySQL Server Severity:S1 (Critical)
Version:5.0.45 OS:Linux (64bits)
Assigned to: CPU Architecture:Any

[16 Oct 2007 14:02] Tordjman Yohan 
Description:
With this request on the tables joinded*, the mysql server works forever on nothing ... ?

select id_msg, titre_msg, corps, date_redaction, heure, pseudo, email, lib_theme, id_theme  from blog_blog, blog_user, blog_theme order by date_redaction desc, heure desc limit 0,1;

*How to attach them ? I don't remember... 

How to repeat:
select id_msg, titre_msg, corps, date_redaction, heure, pseudo, email, lib_theme, id_theme  from blog_blog, blog_user, blog_theme order by date_redaction desc, heure desc limit 0,1;

Suggested fix:
display an error or something like that ?
[16 Oct 2007 14:03] Tordjman Yohan 
the file with the tables are uploaded... :-)
[16 Oct 2007 20:04] Sveta Smirnova 
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://dev.mysql.com/doc/ and the instructions on
how to report a bug at http://bugs.mysql.com/how-to-report.php

The query should process 578 * 13 * 778 = 5845892 rows before returning result. It takes time.
[16 Oct 2007 20:47] Tordjman Yohan 
Ok, but i don't think that kind of query is really valid... or... there are a need to make some parameter like "max rows per query".

This kind of query make a bi opteron, 6Gb ram, 2 RAID1 soft SAS 15Krpm HDD, completely down. (the disks does 80Mo/s writing a tmp table...)

Do a hosting service need, now, to wary about such little tables ?