MySQL Settings

Show status of InnoDB:

mysql -u root 
show innodb status;

See what MySQL is doing (e.g. expensive query):

show processlist;

Check the current structure of a table, including foreign key constraints. This can be helpful in resolving issues caused by db mode 'update', which only adds columns but will not change an existing column:

show create table _Alias;

We use the following settings for MySQL on our production server (NixOS/Linux):

[mysqld]
key_buffer_size = 256M
max_allowed_packet = 64M
sort_buffer_size = 2M
read_buffer_size = 2M
myisam_sort_buffer_size = 64M
query_cache_size = 128M
max_connections = 250

[mysqldump]
max_allowed_packet = 16M

[isamchk]
key_buffer = 256M
sort_buffer_size = 256M

[myisamchk]
key_buffer = 256M
sort_buffer_size = 256M