Comment 3 for bug 955776

Hi Elena

The server we tried this upgrade at, is not used in a 'normal' way. Instead of single mysqld, we run several hundred of mysqld processes on it to provide 'separate mysql server' feature to our customers. So I can't say if performance improved or not. What we noticed is that the total Load Average on this server increased very high and the whole service went down few times. Disk IO was not the case but we saw 100% CPU usage frequently while it never happened before upgrade. Then I tried different optimizer_switch combinations until we decided to downgrade back to 5.2.

For the most of these mysqld instances we use the same configuration with innodb, pbxt, blackhole, archive and federated engines disabled (so only MyISAM is used in fact) and key-buffer-size/aria_pagecache_buffer_size set to 8m.

Taking some random mysqld instances into account I can say that slow-query-log was normally empty before upgrade but started to grow up after. But I am not sure if this is because of MariaDB itself or because of high Load Average and system slow down it caused. At the moment we run on 5.2 with path for bug 909635 applied.

The attached picture shows what happened on the server.