1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3 4<html> 5 6<head> 7 8<title>Postfix CDB Howto</title> 9 10<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 11<link rel='stylesheet' type='text/css' href='postfix-doc.css'> 12 13</head> 14 15<body> 16 17<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix CDB Howto</h1> 18 19<hr> 20 21<h2>Introduction</h2> 22 23<p> CDB (Constant DataBase) is an indexed file format designed by 24Daniel Bernstein. CDB is optimized exclusively for read access 25and guarantees that each record will be read in at most two disk 26accesses. This is achieved by forgoing support for incremental 27updates: no single-record inserts or deletes are supported. CDB 28databases can be modified only by rebuilding them completely from 29scratch, hence the "constant" qualifier in the name. </p> 30 31<p> Postfix CDB databases are specified as "<a href="CDB_README.html">cdb</a>:<i>name</i>", where 32<i>name</i> specifies the CDB file name without the ".cdb" suffix 33(another suffix, ".tmp", is used temporarily while a CDB file is 34under construction). CDB databases are maintained with the <a href="postmap.1.html">postmap(1)</a> 35or <a href="postalias.1.html">postalias(1)</a> command. The <a href="DATABASE_README.html">DATABASE_README</a> document has general 36information about Postfix databases. </p> 37 38<p> CDB support is available with Postfix 2.2 and later releases. 39This document describes how to build Postfix with CDB support. </p> 40 41<h2>Building Postfix with CDB support</h2> 42 43<p> These instructions assume that you build Postfix from source 44code as described in the <a href="INSTALL.html">INSTALL</a> document. Some modification may 45be required if you build Postfix from a vendor-specific source 46package. </p> 47 48<p> Postfix is compatible with two CDB implementations: </p> 49 50<ul> 51 52<li> <p> The original cdb library from Daniel Bernstein, available 53from <a href="http://cr.yp.to/cdb.html">http://cr.yp.to/cdb.html</a>, and </p> 54 55<li> <p> tinycdb (version 0.5 and later) from Michael Tokarev, 56available from <a href="http://www.corpit.ru/mjt/tinycdb.html">http://www.corpit.ru/mjt/tinycdb.html</a>. </p> 57 58</ul> 59 60<p> Tinycdb is preferred, since it is a bit faster, has additional 61useful functionality and is much simpler to use. </p> 62 63<p>To build Postfix after you have installed tinycdb, use something 64like: </p> 65 66<blockquote> 67<pre> 68% make tidy 69% CDB=../../../tinycdb-0.5 70% make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \ 71 "<a href="CDB_README.html">AUXLIBS_CDB</a>=$CDB/libcdb.a" 72% make 73</pre> 74</blockquote> 75 76<p> Alternatively, for the D.J.B. version of CDB:<p> 77 78<blockquote> 79<pre> 80% make tidy 81% CDB=../../../cdb-0.75 82% make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \ 83 "<a href="CDB_README.html">AUXLIBS_CDB</a>=$CDB/cdb.a $CDB/alloc.a $CDB/buffer.a $CDB/unix.a $CDB/byte.a" 84% make 85</pre> 86</blockquote> 87 88<p> Postfix versions before 3.0 use AUXLIBS instead of <a href="CDB_README.html">AUXLIBS_CDB</a>. 89With Postfix 3.0 and later, the old AUXLIBS variable still supports 90building a statically-loaded CDB database client, but only the new 91<a href="CDB_README.html">AUXLIBS_CDB</a> variable supports building a dynamically-loaded or 92statically-loaded CDB database client. </p> 93 94<blockquote> 95 96<p> Failure to use the <a href="CDB_README.html">AUXLIBS_CDB</a> variable will defeat the purpose 97of dynamic database client loading. Every Postfix executable file 98will have CDB database library dependencies. And that was exactly 99what dynamic database client loading was meant to avoid. </p> 100 101</blockquote> 102 103<p> After Postfix has been built with cdb support, you can use 104"cdb" tables wherever you can use read-only "hash", "btree" or 105"dbm" tables. However, the "<b>postmap -i</b>" (incremental record 106insertion) and "<b>postmap -d</b>" (incremental record deletion) 107command-line options are not available. For the same reason the 108"cdb" map type cannot be used to store the persistent address 109verification cache for the <a href="verify.8.html">verify(8)</a> service, or to store 110TLS session information for the <a href="tlsmgr.8.html">tlsmgr(8)</a> service. </p> 111
