squirrelmail/doc/db-backend.txt

$Id$


Storing private addressbooks and preferences in a database
==========================================================


On sites with many users you might want to store your user data in a
database instead of in files. This document describes how to configure
SquirrelMail to do this.

Methods for storing both personal addressbooks and user preferences in
a database is included as a part of the distribution.



Configuring PEAR DB
-------------------

For this to work you must have the PEAR classes installed, these are
part of PHP. Once these are installed you must have sure the directory
containg them is a part of your PHP include path. See the PHP
documentation for information on how to do that.
Under Mandrake Linux the PEAR classes are installed as part of the
php-devel package and under FreeBSD they are installed as part of
the mod_php4 or php4 port/package. In Debian, you can install the
php4-pear package. I'm afraid I have no information on
other systems at the present time.


Configuring addressbooks in database
------------------------------------

First you need to create a database and a table to store the data in.
Create a database user with access to read and write in that table.

For MySQL you would normally do something like:

 (from the command line)
 # mysqladmin create squirrelmail

 (from the mysql client)
 mysql> GRANT select,insert,update,delete ON squirrelmail.*
              TO squirreluser@localhost IDENTIFIED BY 'sqpassword';

The table structure should be similar to this (for MySQL):

   CREATE TABLE address (
     owner varchar(128) DEFAULT '' NOT NULL,
     nickname varchar(16) DEFAULT '' NOT NULL,
     firstname varchar(128) DEFAULT '' NOT NULL,
     lastname varchar(128) DEFAULT '' NOT NULL,
     email varchar(128) DEFAULT '' NOT NULL,
     label varchar(255),
     PRIMARY KEY (owner,nickname),
     KEY firstname (firstname,lastname)
   );

and similar to this for PostgreSQL:
CREATE TABLE "address" (
   "owner" varchar(128) NOT NULL,
   "nickname" varchar(16) NOT NULL,
   "firstname" varchar(128) NOT NULL,
   "lastname" varchar(128) NOT NULL,
   "email" varchar(128) NOT NULL,
   "label" varchar(255) NOT NULL,
   CONSTRAINT "address_pkey" PRIMARY KEY ("nickname", "owner")
);
CREATE  UNIQUE INDEX "address_firstname_key" ON "address"
   ("firstname", "lastname");


Next, edit your configuration so that the address book DSN (Data Source
Name) is specified, this can be done using either conf.pl or via the
administration plugin. The DSN should look something like:

 mysql://squirreluser:sqpassword@localhost/squirrelmail or
 pgsql://squirreluser:sqpassword@localhost/squirrelmail

From now on all users' personal addressbooks will be stored in a
database.

Global address book uses same table format as the one used for personal
address book. You can even use same table, if you don't have user named
'global'.

Configuring preferences in database
-----------------------------------

This is done in much the same way as it is for storing your address
books in a database.

The table structure should be similar to this (for MySQL):

  CREATE TABLE userprefs (
    user varchar(128) DEFAULT '' NOT NULL,
    prefkey varchar(64) DEFAULT '' NOT NULL,
    prefval BLOB DEFAULT '' NOT NULL,
    PRIMARY KEY (user,prefkey)
  );

and for PostgreSQL:
CREATE TABLE "userprefs" (
   "username" varchar(128) NOT NULL,
   "prefkey" varchar(64) NOT NULL,
   "prefval" text,
   CONSTRAINT "userprefs_pkey" PRIMARY KEY ("prefkey", "username")
);

Next, edit your configuration so that the preferences DSN (Data Source
Name) is specified, this can be done using either conf.pl or via the
administration plugin. The DSN should look something like:

 mysql://squirreluser:sqpassword@localhost/squirrelmail or
 pgsql://squirreluser:sqpassword@localhost/squirrelmail

Note that when using the above PostgreSQL schema, you also need to change
the prefs_user_field variable in config.php from the default 'user' to
'username'.

From now on all users' personal preferences will be stored in a
database.

Default preferences can be set by altering the $default array in
db_prefs.php.

Troubleshooting
---------------
1. Oversized field values. Preferences are not/can't be saved

Database fields have size limits. Preference table example sets 128 
character limit to owner field, 64 character limit to preference key 
field and 64KB (database BLOB field size) limit to value field.

If interface tries to insert data without checking field limits, it
can cause data loss or database errors. Table information functions
provided by Pear DB libraries are not accurate and some database
backends don't support them. Since 1.5.1 SquirrelMail provides
configuration options that set allowed field sizes.

If you see oversized field errors in your error logs - check your
database structure. Issue can be solved by increasing database field
sizes.

If you want to get more debugging information - check setKey() function 
in dbPrefs class. Class is stored in functions/db_prefs.php