mysql home 

   directory

bin

data

mysql

itsodb

installed

databases

  ...

docs

include

lib

man

scripts

  ...

Figure 1 13   MySQL directory structure

In our example, the installed databases are 

mysql, 

which by default holds the 

security information and our sample database 

itsodb

. For each database there is 

a directory that contains three files per table. Files with the `MYD' extension 

contains the table data. Files with the `MYI' extension contains the table's 

indexes. Files with the

 frm

 extension contain the table's structure definition 

known as the 

schema

. All these tables are MyISAM type tables. Log files per 

default are created in the 

data

 directory. The security information data tables are 

in the directory 

/data/mysql.

Table 1 3 lists the security information data tables.

Table 1 3   Permission information stored in tables

File

Description

columns_priv.MYD

columns_priv.MYI

Permission for individual columns within a table

columns_priv.frm

db.MYD

db.MYI

Permission for individual tables

db.frm

func.MYD

func.MYI

Permission for user defined functions

func.frm

 Chapter 1. Introduction 

33