Be careful about increasing the default value as this will have an impact on the per connection memory usage. For each connection made by a client to the
MySQL server, buffer memory is allocated according to this formula (I've put similar buffers together and these are the important ones):
Per connection memory usage = thread_stack +
net_buffer_length + max_allowed_packet +
read_buffer_size + read_rnd_buffer_size +
sort_buffer_size + myisam_sort_buffer_size +
join_buffer_size +
bulk_insert_buffer_sizeSo this gives
Total connection memory usage = Per connection memory usage * max_connectionsNotice the multiplying factor - if you increase max_connections you'll get a multiplying of the memory usage. It's best practice to make sure that you don't allow the server to exceed it's free RAM, otherwise it'll start swapping memory to disk and things will slow down considerably.
By all means increase the value of max_connections - but remember that connections last for milliseconds, so only do it when you're expecting a peak in usage and know that the maximum value that you can increase it to depends on the free RAM in your server.
Hope this helps!
Ken
