Tag: Refactoring

This post continues Getting rid of huge ibdata file, no dump required, part I, where I describe way of converting your single-tablespace InnoDB database into a file-per-table one, without the pain of exporting and importing everything at once.

In previous part we put aside the issue of foreign keys. We address this issue now.

What if my InnoDB tables have foreign keys?

MyISAM does not support them, so you can’t just ALTER an InnoDB table to MyISAM and back into InnoDB, and expect everything to work.

Alas, this calls for additional steps (i.e. additional ALTER commands). However, these still fall well under the concept of “do it one table at a time, then take time to recover your breath and replication lag”.

Save , drop and restore your Foreign Keys setup

You can use common_schema‘s  sql_foreign_keys to get the full listing and create definition of your foreign keys. For example, assume we use the sakila database: Continue reading » “Getting rid of huge ibdata file, no dump required, part II”

You have been told (guilty as charged), that the only way to get rid of the huge InnoDB tablespace file (commonly named ibdata1), when moving to innodb_file_per_table, is to do a logical dump of your data, completely erase everything, then import the dump.

To quickly reiterate, you can only delete the ibdata1 file when no InnoDB tables exist. Delete this file with an existing InnoDB table, even a table in its own tablespace, and nothing ever works anymore.

The problem with the dump-based solution

The impact of doing a logical dump is often overwhelming. Well, the dump may be tolerable, but the restore is much longer. The real pain is that you can’t do this one table at a time: you have to destroy everything before dropping the ibdata1 file; you then have to import everything.

Perhaps the most common scenario is that we do the changes on a slave, so as not to completely shut down our database. This is nice; no one is aware of the shutdown process. However, Huston, we have a problem: we need to make sure we can keep up the binary logs on the master for the duration of the entire process. Continue reading » “Getting rid of huge ibdata file, no dump required”