openldap/doc/man/man5/slapd-bdb.5

.TH SLAPD-BDB 5 "RELEASEDATE" "OpenLDAP LDVERSION"
.\" Copyright 1998-2005 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.\" $OpenLDAP$
.SH NAME
slapd-bdb, slapd-hdb \- Berkeley DB backends to slapd
.SH SYNOPSIS
ETCDIR/slapd.conf
.SH DESCRIPTION
The BDB backend to
.BR slapd (8)
is the recommended backend for a normal slapd database.
However, it takes more care than with the LDBM backend to configure
it properly.
It uses the Sleepycat Berkeley DB (BDB) package to store data.
It makes extensive use of indexing and caching to speed data access.
.LP
"hdb" is a variant of the BDB backend that uses a hierarchical database
layout which supports subtree renames. It is otherwise identical to
the "bdb" 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 DB_CONFIG
file.  See Berkeley DB documentation for details on
.B DB_CONFIG
configuration options.
Where there is overlap, settings in
.B DB_CONFIG
take precedence.
.SH CONFIGURATION
These
.B slapd.conf
options apply to the BDB backend database.
That is, they must follow a "database bdb" or "database hdb" line and
come before any subsequent "backend" or "database" lines.
Other database options are described in the
.BR slapd.conf (5)
manual page.
.TP
.B cachesize <integer>
Specify the size in entries of the in-memory entry cache maintained 
by the BDB backend database instance.
The default is 1000 entries.
.TP
.B checkpoint <kbyte> <min>
Specify the frequency for checkpointing the database transaction log.
A checkpoint operation flushes the database buffers to disk and writes
a checkpoint record in the log.
The checkpoint will occur if either <kbyte> data has been written or
<min> minutes have passed since the last checkpoint.
Both arguments default to zero, in which case they are ignored. When
the <min> argument is non-zero, an internal task will run every <min>
minutes to perform the checkpoint.
See the Berkeley DB reference guide for more details.
.TP
.B dbconfig <Berkeley DB setting>
Specify a configuration directive to be placed in the
.B DB_CONFIG
file of the database directory. The
.B dbconfig
directive is just a convenience
to allow all necessary configuration to be set in the
.B slapd.conf
file.
The options set using this directive will only be written to the DB_CONFIG
file if no such file existed at server startup time. This allows one
to set initial values without overwriting/destroying a DB_CONFIG file
that was already customized through other means. This directive may
be specified multiple times, as needed. For example
.RS
.nf
	dbconfig set_cachesize 0 1048576 0
	dbconfig set_lg_bsize 2097152
.fi
.RE
.TP
.B dbnosync
Specify that on-disk database contents should not be immediately
synchronized with in memory changes.
Enabling this option may improve performance at the expense of data
security.
See the Berkeley DB reference guide for more details.
.TP
.B directory <directory>
Specify the directory where the BDB files containing this database and
associated indexes live.
A separate directory must be specified for each database.
The default is
.BR LOCALSTATEDIR/openldap-data .
.TP
.B dirtyread
Allow reads of modified but not yet committed data.
Usually transactions are isolated to prevent other operations from
accessing uncommitted data.
This option may improve performance, but may also return inconsistent
results if the data comes from a transaction that is later aborted.
In this case, the modified data is discarded and a subsequent search
will return a different result.
.TP
.B idlcachesize <integer>
Specify the size of the in-memory index cache, in index slots. The
default is zero. A larger value will speed up frequent searches of
indexed entries. An hdb database needs a large idlcachesize
for good search performance, typically three times the entry cache size
or larger.
.TP
.B
index {<attrlist>|default} [pres,eq,approx,sub,<special>]
Specify the indexes to maintain for the given attribute (or
list of attributes).
Some attributes only support a subset of indexes.
If only an <attr> is given, the indices specified for \fBdefault\fR
are maintained.
Note that setting a default does not imply that all attributes will be
indexed. Also, for best performance, an
.B eq
index should always be configured for the
.B objectClass
attribute.

A number of special index parameters may be specified.
The index type
.B sub
can be decomposed into
.BR subinitial ,
.BR subany ,\ and
.B subfinal
indices.
The special type
.B nolang
may be specified to disallow use of this index by language subtypes.
The special type
.B nosubtypes
may be specified to disallow use of this index by named subtypes.
Note: changing index settings requires rebuilding indices, see
.BR slapindex (8).
.TP
.B linearindex
Tell slapindex to index one attribute at a time. By default, all indexed
attributes in an entry are processed at the same time. With this option,
each indexed attribute is processed individually, using multiple passes
through the entire database. This option improves slapindex performance
when the database size exceeds the dbcache size. When the dbcache is
large enough, this option is not needed and will decrease performance.
Also by default, slapadd performs full indexing and so a separate slapindex
run is not needed. With this option, slapadd does no indexing and slapindex
must be used.
.TP
.B lockdetect {oldest|youngest|fewest|random|default}
Specify which transaction to abort when a deadlock is detected.
The default is the same as
.BR random .
.TP
.B mode <integer>
Specify the file protection mode that newly created database 
index files should have.
The default is 0600.
.TP
.B searchstack <depth>
Specify the depth of the stack used for search filter evaluation.
Search filters are evaluated on a stack to accommodate nested AND / OR
clauses. An individual stack is assigned to each server thread.
The depth of the stack determines how complex a filter can be
evaluated without requiring any additional memory allocation. Filters that
are nested deeper than the search stack depth will cause a separate
stack to be allocated for that particular search operation. These
allocations can have a major negative impact on server performance,
but specifying too much stack will also consume a great deal of memory.
Each search stack uses 512K bytes per level. The default stack depth
is 16, thus 8MB per thread is used.
.TP
.B shm_key <integer>
Specify a key for a shared memory BDB environment. By default the
BDB environment uses memory mapped files. If a non-zero value is
specified, it will be used as the key to identify a shared memory
region that will house the environment.
.B
.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.TP
DB_CONFIG
Berkeley DB configuration file
.SH SEE ALSO
.BR slapd.conf (5),
.BR slapd (8),
.BR slapadd (8),
.BR slapcat (8),
.BR slapindex (8),
Berkeley DB documentation.