.TH SLAPD-BDB 5 "RELEASEDATE" "OpenLDAP LDVERSION"
-.\" Copyright 1998-2009 The OpenLDAP Foundation All Rights Reserved.
+.\" Copyright 1998-2012 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply. See COPYRIGHT/LICENSE.
.\" $OpenLDAP$
.SH NAME
-slapd-bdb, slapd-hdb \- Berkeley DB backends to slapd
+slapd\-bdb, slapd\-hdb \- Berkeley DB backends to slapd
.SH SYNOPSIS
.B ETCDIR/slapd.conf
.SH DESCRIPTION
The \fBbdb\fP backend to
.BR slapd (8)
-is the recommended primary backend for a normal
-.B slapd
-database.
-It uses the Oracle Berkeley DB (BDB) package to store data.
+uses the Oracle Berkeley DB (BDB) package to store data.
It makes extensive use of indexing and caching to speed data access.
.LP
-\fBhdb\fP is a variant of the \fBbdb\fP backend that uses a
-hierarchical database
-layout which supports subtree renames. It is otherwise identical to
-the \fBbdb\fP behavior, and all the same configuration options apply.
+\fBhdb\fP is the recommended primary database backend. It is a variant of
+the \fBbdb\fP backend that uses a hierarchical database layout which
+supports subtree renames. It is both more space-efficient and more
+execution-efficient than the \fBbdb\fP backend. It is otherwise identical
+to the \fBbdb\fP behavior, and all the same configuration options apply.
.LP
It is noted that these options are intended to complement
Berkeley DB configuration options set in the environment's
.B cryptfile
may be configured.
.TP
-.BI dbconfig \ <Berkeley\-DB\-setting>
+.BI dbconfig \ <Berkeley-DB-setting>
Specify a configuration directive to be placed in the
.B DB_CONFIG
file of the database directory. The
underlying filesystem's block size (typically 4 or 8).
The maximum that BerkeleyDB supports is 64. This
setting usually should not need to be changed, but if BerkeleyDB's
-"db_stat -d" shows a large amount of overflow pages in use in a file,
+"db_stat \-d" shows a large amount of overflow pages in use in a file,
setting a larger size may increase performance at the expense of
data integrity. This setting only takes effect when a database is
being newly created. See the Berkeley DB reference guide for more details.
associated indexes live.
A separate directory must be specified for each database.
The default is
-.BR LOCALSTATEDIR/openldap-data .
+.BR LOCALSTATEDIR/openldap\-data .
.TP
.B dirtyread
Allow reads of modified but not yet committed data.
will return a different result.
.TP
.BI dncachesize \ <integer>
-Specify the maximum number of DNs in the in-memory DN cache. The
-default is twice the \fBcachesize\fP. Ideally this cache should be
-large enough to contain the DNs of every entry in the database.
+Specify the maximum number of DNs in the in-memory DN cache.
+Ideally this cache should be
+large enough to contain the DNs of every entry in the database. If
+set to a smaller value than the \fBcachesize\fP it will be silently
+increased to equal the \fBcachesize\fP. The default value is 0 which
+means unlimited, i.e. the DN cache will grow without bound.
+
+It should be noted that the \fBDN cache\fP is allowed to temporarily
+grow beyond the configured size. It does this if many entries are
+locked when it tries to do a purge, because that means they're
+legitimately in use. Also, the \fBDN cache\fP never purges entries
+that have cached children, so depending on the shape of the DIT, it
+could have lots of cached DNs over the defined limit.
.TP
.BI idlcachesize \ <integer>
Specify the size of the in-memory index cache, in index slots. The
Berkeley DB configuration file
.SH SEE ALSO
.BR slapd.conf (5),
+.BR slapd\-config (5),
.BR slapd (8),
.BR slapadd (8),
.BR slapcat (8),
projects / openldap / blobdiff