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<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix PostgreSQL Howto</h1>

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<h2>Introduction</h2>

<p> The Postfix pgsql map type allows you to hook up Postfix to a
PostgreSQL database.  This implementation allows for multiple pgsql
databases: you can use one for a virtual(5) table, one for an
access(5) table, and one for an aliases(5) table if you want.  You
can specify multiple servers for the same database, so that Postfix
can switch to a good database server if one goes bad.  </p>

<p> Busy mail servers using pgsql maps will generate lots of
concurrent pgsql clients, so the pgsql server(s) should be run with
this fact in mind. You can reduce the number of concurrent pgsql
clients by using the Postfix proxymap(8) service. </p>

<h2>Building Postfix with PostgreSQL support</h2>

<p> These instructions assume that you build Postfix from source
code as described in the INSTALL document. Some modification may
be required if you build Postfix from a vendor-specific source
package.  </p>

<p> Note: to use pgsql with Debian GNU/Linux's Postfix, all you
need to do is to install the postfix-pgsql package and you're done.
There is no need to recompile Postfix. </p>

<p> In order to build Postfix with pgsql map support, you specify
-DHAS_PGSQL, the directory with the PostgreSQL header files, and
the location of the libpq library file. </p>

<p> For example: </p>

<blockquote>
<pre>
% make tidy
% make -f Makefile.init makefiles \
        'CCARGS=-DHAS_PGSQL -I/usr/local/include/pgsql' \
        'AUXLIBS_PGSQL=-L/usr/local/lib -lpq'
</pre>
</blockquote>

<p> Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_PGSQL.
With Postfix 3.0 and later, the old AUXLIBS variable still supports
building a statically-loaded PostgreSQL database client, but only
the new AUXLIBS_PGSQL variable supports building a dynamically-loaded
or statically-loaded PostgreSQL database client.  </p>

<blockquote>

<p> Failure to use the AUXLIBS_PGSQL variable will defeat the purpose
of dynamic database client loading. Every Postfix executable file
will have PGSQL database library dependencies. And that was exactly
what dynamic database client loading was meant to avoid. </p>

</blockquote>

<p> Then just run 'make'.  </p>

<h2>Configuring PostgreSQL lookup tables</h2>

<p> Once Postfix is built with pgsql support, you can specify a
map type in main.cf like this: </p>

<blockquote>
<pre>
/etc/postfix/main.cf:
    alias_maps = pgsql:/etc/postfix/pgsql-aliases.cf
</pre>
</blockquote>

<p> The file /etc/postfix/pgsql-aliases.cf specifies lots of
information telling postfix how to reference the pgsql database.
For a complete description, see the pgsql_table(5) manual page. </p>

<h2>Example: local aliases </h2>

<pre>
#
# pgsql config file for local(8) aliases(5) lookups
#

#
# The hosts that Postfix will try to connect to
hosts = host1.some.domain host2.some.domain

# The user name and password to log into the pgsql server.
user = someone
password = some_password

# The database name on the servers.
dbname = customer_database

# Postfix 2.2 and later The SQL query template. See pgsql_table(5).
query = SELECT forw_addr FROM mxaliases WHERE alias='%s' AND status='paid'

# For Postfix releases prior to 2.2. See pgsql_table(5) for details.
select_field = forw_addr
table = mxaliases
where_field = alias
# Don't forget the leading "AND"!
additional_conditions = AND status = 'paid'
</pre>

<h2>Using mirrored databases</h2>

<p> Sites that have a need for multiple mail exchangers may enjoy
the convenience of using a networked mailer database, but do not
want to introduce a single point of failure to their system.   </p>

<p> For this reason we've included the ability to have Postfix
reference multiple hosts for access to a single pgsql map.  This
will work if sites set up mirrored pgsql databases on two or more
hosts. </p>

<p> Whenever queries fail with an error at one host, the rest of
the hosts will be tried in random order.  If no pgsql server hosts
are reachable, then mail will be deferred until at least one of
those hosts is reachable. </p>

<h2>Credits</h2>

<ul>

<li> This code is based upon the Postfix mysql map by Scott Cotton
and Joshua Marcus, IC Group, Inc.</li>

<li> The PostgreSQL changes were done by Aaron Sethman.</li>

<li> Updates for Postfix 1.1.x and PostgreSQL 7.1+ and support for
calling stored procedures were added by Philip Warner.</li>

<li> LaMont Jones was the initial Postfix pgsql maintainer.</li>

<li> Liviu Daia revised the configuration interface and added the
main.cf configuration feature.</li>

<li> Liviu Daia revised the configuration interface and added the main.cf
configuration feature.</li>

<li> Liviu Daia with further refinements from Jose Luis Tallon and
Victor Duchovni developed the common query, result_format, domain and
expansion_limit interface for LDAP, MySQL and PosgreSQL.</li>

<li> Leandro Santi updated the PostgreSQL client after the PostgreSQL
developers made major database API changes in response to SQL
injection problems, and made PQexec() handling more robust. </li>

</ul>

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