MySQL, InnoDB and replications
I had a lot of fun yesterday. I wanted to optimize the InnoDB storage
in one of my projects. I realized that the innodb_data_file_path MySQL
parameter doesn't allow you to specify the very simple case: whenever
you need a new innodb datafile, add it, but limit its size to
e.g. 1GB. The only method to do so is to periodically monitor the file
size of the last (autoextending) data file. Another method is to
pre-define several 1GB files and keep the last one as e.g. 10MB and
autoextending and monitor its size. It would be nice to have this
possibility.
But that was not fun. The real fun was when I realised that the
described method to start replication with empty master and slave
can't work as described, because the databases test and test_% are
special in mysql database. This caused me two hours of debugging to
realize that the bug is in the manual describing something that can't
work by design ;-) But when I realized it, the complete process took
me 5 minutes.