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