Re: Definitions in the frm file

Hi!

On Jul 18, Bjørn Normann wrote:
> I'm working on a master dissertation about forensics investigation in
> a MySQL database system. I have gone through the definition of the
> .frm file and find some unclear information in the internals manual.
>
> I need more information about the key area. It doesn't say anything
> about how the keys or indexes are stored in the .frm file.

Check the source. For example (in 5.1).
You need this function:
http://dev.mysql.com/sources/doxygen/mysql-5.1/table_8cc.html#90fcadffe69b32708bc42f9c71792524

keys are read from the frm file in lines 00527-00578, and 00690-00712. It's easy to understand, for example:

00532       keyinfo->flags=      (uint) uint2korr(strpos) ^ HA_NOSAME;
00533       keyinfo->key_length= (uint) uint2korr(strpos+2);
00534       keyinfo->key_parts=  (uint) strpos[4];
00535       keyinfo->algorithm=  (enum ha_key_alg) strpos[5];
00536       keyinfo->block_size= uint2korr(strpos+6);
00537       strpos+=8;

means

• two bytes for flags (with inverted HA_NOSAME bit)
• two bytes for key length
• one byte - number of key parts
• one byte for key algorithm
• two bytes - key block size

Regards / Mit vielen Grüssen,
Sergei

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