Recently we announced MySQL Data Recovery Portal. Here we automated some data recovery routines and published web interface to them.

First, it was a tool to estimate recovery chances from corrupted InnoDB tablespaces.

Now it’s even more exciting and useful feature – recovery table structure from FRM files online.

There are several methods to recover MySQL table structure from FRM files.

On MySQL Data Recovery Portal we utilize a combination of them.

Fake table method

The idea is to create a dummy InnoDB table, replace its .frm file with .frm file we want to recover and run SHOW CREATE TABLE.

Let’s say we have actor.frm and we want to get structure of table actor.

Algorithm is following:

Create a dummy table with the same name, actor. The …

When a table gets dropped MySQL removes respective .frm file. This post explain how to recover table structure if the table was dropped.

You need the table structure to recover a dropped table from InnoDB tablespace. The B+tree structure of InnoDB index doesn’t contain any information about field types. MySQL needs to know that in order to access records of InnoDB table. Normally MySQL gets the table structure from .frm file. But when MySQL drops a table the respective frm file removed too.

Fortunately there is one more place where MySQL keeps the tables structure . It is the InnoDB dictionary.

InnoDB dictionary is a set of tables where InnoDB keeps some information about the tables. I reviewed them in details is a separate InnoDB Dictionary post earlier. After the DROP InnoDB deletes records related to the dropped table from the dictionary. So we need …