Today as i was learning for the new MySQL 5.6-certification (more about that in a later post) i stumbled again across the host_cache-Table that was added to MySQL in 5.6.5. Before that you had no chance to check which hosts are already known by the MySQL-server.
So thats a pretty good feature for us. And even better: you could resize the size of the host_cache now! Whoohoo, awesome! As we have a lot of servers that need to connect to one of our MySQL-server and we could not switch to ip-based-authentication we were really happy to tune the host_cache-size without recompiling MySQL.
Unfortunately i noticed that the performance_schema.host_cache table only holds 128 rows and that the content was changing everytime i checked. So i logged in to a server that wasn’t already in the host_cache-table, made a connection attempt to the mysql server and checked again the host_cache-table:
The server was now in the host_cache-table but still the table held only 128 rows though the host_cache_size-variable was set to 2000. :/
You can see my bug report here: http://bugs.mysql.com/bug.php?id=70552
Hopefully it won’t take Oracle years to fix this 😉