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+PPoossttffiixx CCDDBB HHoowwttoo
+
+-------------------------------------------------------------------------------
+
+IInnttrroodduuccttiioonn
+
+CDB (Constant DataBase) is an indexed file format designed by Daniel Bernstein.
+CDB is optimized exclusively for read access and guarantees that each record
+will be read in at most two disk accesses. This is achieved by forgoing support
+for incremental updates: no single-record inserts or deletes are supported. CDB
+databases can be modified only by rebuilding them completely from scratch,
+hence the "constant" qualifier in the name.
+
+Postfix CDB databases are specified as "cdb:name", where name specifies the CDB
+file name without the ".cdb" suffix (another suffix, ".tmp", is used
+temporarily while a CDB file is under construction). CDB databases are
+maintained with the postmap(1) or postalias(1) command. The DATABASE_README
+document has general information about Postfix databases.
+
+CDB support is available with Postfix 2.2 and later releases. This document
+describes how to build Postfix with CDB support.
+
+BBuuiillddiinngg PPoossttffiixx wwiitthh CCDDBB ssuuppppoorrtt
+
+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.
+
+Postfix is compatible with two CDB implementations:
+
+ * The original cdb library from Daniel Bernstein, available from http://
+ cr.yp.to/cdb.html, and
+
+ * tinycdb (version 0.5 and later) from Michael Tokarev, available from http:/
+ /www.corpit.ru/mjt/tinycdb.html.
+
+Tinycdb is preferred, since it is a bit faster, has additional useful
+functionality and is much simpler to use.
+
+To build Postfix after you have installed tinycdb, use something like:
+
+ % make tidy
+ % CDB=../../../tinycdb-0.5
+ % make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \
+ "AUXLIBS_CDB=$CDB/libcdb.a"
+ % make
+
+Alternatively, for the D.J.B. version of CDB:
+
+ % make tidy
+ % CDB=../../../cdb-0.75
+ % make -f Makefile.init makefiles "CCARGS=-DHAS_CDB -I$CDB" \
+ "AUXLIBS_CDB=$CDB/cdb.a $CDB/alloc.a $CDB/buffer.a $CDB/unix.a $CDB/
+ byte.a"
+ % make
+
+Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_CDB. With Postfix
+3.0 and later, the old AUXLIBS variable still supports building a statically-
+loaded CDB database client, but only the new AUXLIBS_CDB variable supports
+building a dynamically-loaded or statically-loaded CDB database client.
+
+ Failure to use the AUXLIBS_CDB variable will defeat the purpose of dynamic
+ database client loading. Every Postfix executable file will have CDB
+ database library dependencies. And that was exactly what dynamic database
+ client loading was meant to avoid.
+
+After Postfix has been built with cdb support, you can use "cdb" tables
+wherever you can use read-only "hash", "btree" or "dbm" tables. However, the
+"ppoossttmmaapp --ii" (incremental record insertion) and "ppoossttmmaapp --dd" (incremental
+record deletion) command-line options are not available. For the same reason
+the "cdb" map type cannot be used to store the persistent address verification
+cache for the verify(8) service, or to store TLS session information for the
+tlsmgr(8) service.
+