Hello,
Thanks for your answer fast and pertinent answer peter.
I read the mentioned document yesterday from the following thread and learned a lot about:
"MySQL 5.5.31 cripplingly slow"
http://forums.mysql.com/read.php?24,603739,603757#msg-603757
However, I tried several set of settings based on that, I also used MySQLTuner without more luck.
I'm not the developer, but I checked the query they are executing and it appears that the problem come from the statement itself (like often).
In the "WHERE" clause there is a "IN" calling a SELECT statement
ie. SELECT field FROM table WHERE field IN (SELECT field FROM table)
Removing the "sub" select and specifying a list of value solve the problem.
Executing this "SUB" select alone take a few milliseconds.
So my main question remain, which settings would make such a difference of performance on this kind of statement?
FYI tmp_table_size and max_heap_table_size values are the same on fast and slow servers.
I would appreciate any assistance.
Thanks in advance.
Kind regards
Julien