dist/html/CDB_README.html

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1.1  tron <title>Postfix CDB Howto</title>
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1.1  tron <h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix CDB Howto</h1>
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1.1  tron <hr>
1.1  tron
1.1  tron <h2>Introduction</h2>
1.1  tron
1.1  tron <p> CDB (Constant DataBase) is an indexed file format designed by
1.1  tron Daniel Bernstein. CDB is optimized exclusively for read access
1.1  tron and guarantees that each record will be read in at most two disk
1.1  tron accesses. This is achieved by forgoing support for incremental
1.1  tron updates: no single-record inserts or deletes are supported.  CDB
1.1  tron databases can be modified only by rebuilding them completely from
1.1  tron scratch, hence the "constant" qualifier in the name.  </p>
1.1  tron
1.1  tron <p> Postfix CDB databases are specified as "<a href="CDB_README.html">cdb</a>:<i>name</i>", where
1.1  tron <i>name</i> specifies the CDB file name without the ".cdb" suffix
1.1  tron (another suffix, ".tmp", is used temporarily while a CDB file is
1.1  tron under construction).  CDB databases are maintained with the <a href="postmap.1.html">postmap(1)</a>
1.1  tron or <a href="postalias.1.html">postalias(1)</a> command. The <a href="DATABASE_README.html">DATABASE_README</a> document has general
1.1  tron information about Postfix databases.  </p>
1.1  tron
1.1  tron <p> CDB support is available with Postfix 2.2 and later releases.
1.1  tron This document describes how to build Postfix with CDB support. </p>
1.1  tron
1.1  tron <h2>Building Postfix with CDB support</h2>
1.1  tron
1.1  tron <p> These instructions assume that you build Postfix from source
1.1  tron code as described in the <a href="INSTALL.html">INSTALL</a> document. Some modification may
1.1  tron be required if you build Postfix from a vendor-specific source
1.1  tron package.  </p>
1.1  tron
1.1  tron <p> Postfix is compatible with two CDB implementations: </p>
1.1  tron
1.1  tron <ul>
1.1  tron
1.1  tron <li> <p> The original cdb library from Daniel Bernstein, available
1.1  tron from <a href="http://cr.yp.to/cdb.html">http://cr.yp.to/cdb.html</a>, and </p>
1.1  tron
1.1  tron <li> <p> tinycdb (version 0.5 and later) from Michael Tokarev,
1.1  tron available from <a href="http://www.corpit.ru/mjt/tinycdb.html">http://www.corpit.ru/mjt/tinycdb.html</a>. </p>
1.1  tron
1.1  tron </ul>
1.1  tron
1.1  tron <p>  Tinycdb is preferred, since it is a bit faster, has additional
1.1  tron useful functionality and is much simpler to use. </p>
1.1  tron
1.1  tron <p>To build Postfix after you have installed tinycdb, use something
1.1  tron like: </p>
1.1  tron
1.1  tron <blockquote>
1.1  tron <pre>
1.1  tron % make tidy
1.1  tron % CDB=../../../tinycdb-0.5
1.1  tron % make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \
1.1  tron     "AUXLIBS=$CDB/libcdb.a"
1.1  tron % make
1.1  tron </pre>
1.1  tron </blockquote>
1.1  tron
1.1  tron <p> Alternatively, for the D.J.B. version of CDB:<p>
1.1  tron
1.1  tron <blockquote>
1.1  tron <pre>
1.1  tron % make tidy
1.1  tron % CDB=../../../cdb-0.75
1.1  tron % make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \
1.1  tron     "AUXLIBS=$CDB/cdb.a $CDB/alloc.a $CDB/buffer.a $CDB/unix.a $CDB/byte.a"
1.1  tron % make
1.1  tron </pre>
1.1  tron </blockquote>
1.1  tron
1.1  tron <p> After Postfix has been built with cdb support, you can use
1.1  tron "cdb" tables wherever you can use read-only "hash", "btree" or
1.1  tron "dbm" tables. However, the "<b>postmap -i</b>" (incremental record
1.1  tron insertion) and "<b>postmap -d</b>" (incremental record deletion)
1.1  tron command-line options are not available. For the same reason the
1.1  tron "cdb" map type cannot be used to store the persistent address
1.1  tron verification cache for the <a href="verify.8.html">verify(8)</a> service, or to store
1.1  tron TLS session information for the <a href="tlsmgr.8.html">tlsmgr(8)</a> service. </p>