NAME
slapd-bdb, slapd-hdb - Berkeley DB backends to slapd
SYNOPSIS
/etc/ldap/slapd.conf
DESCRIPTION
The
bdb backend to
slapd(8)
is the recommended primary backend for a normal
slapd
database.
It uses the Sleepycat Berkeley DB (BDB) package to store data.
It makes extensive use of indexing and caching to speed data access.
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.
It is noted that these options are intended to complement
Berkeley DB configuration options set in the environment's
DB_CONFIG
file. See Berkeley DB documentation for details on
DB_CONFIG
configuration options.
Where there is overlap, settings in
DB_CONFIG
take precedence.
CONFIGURATION
These
slapd.conf
options apply to the
bdb and
hdb 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
slapd.conf(5)
manual page.
I cachesize <integer>
Specify the size in entries of the in-memory entry cache maintained
by the bdb or hdb backend database instance.
The default is 1000 entries.
I cachefree <integer>
Specify the number of entries to free from the entry cache when the
cache reaches the cachesize limit.
The default is 1 entry.
I 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.
I dbconfig <Berkeley-DB-setting>
Specify a configuration directive to be placed in the
DB_CONFIG
file of the database directory. The
dbconfig
directive is just a convenience
to allow all necessary configuration to be set in the
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:
dbconfig set_cachesize 0 1048576 0
dbconfig set_lg_bsize 2097152
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.
I 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
R /var/lib/ldap .
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.
I 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
cachesize
(entry cache size)
or larger.
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
default
are maintained.
Note that setting a default does not imply that all attributes will be
indexed. Also, for best performance, an
eq
index should always be configured for the
objectClass
attribute.
A number of special index parameters may be specified.
The index type
sub
can be decomposed into
R subinitial ,
R subany , and
subfinal
indices.
The special type
nolang
may be specified to disallow use of this index by language subtypes.
The special type
nosubtypes
may be specified to disallow use of this index by named subtypes.
Note: changing
index settings in
slapd.conf(5)
requires rebuilding indices, see
slapindex(8);
changing
index settings
dynamically by LDAPModifying "cn=config" automatically causes rebuilding
of the indices online in a background task.
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.
R lockdetect { oldest | youngest | fewest | random | default }
Specify which transaction to abort when a deadlock is detected.
The default is
R random .
I mode <integer>
Specify the file protection mode that newly created database
index files should have.
The default is 0600.
I 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.
I 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.
ACCESS CONTROL
The
bdb
and
hdb
backends honor access control semantics as indicated in
slapd.access(5).
FILES
/etc/ldap/slapd.conf
default
slapd
configuration file
DB_CONFIG
Berkeley DB configuration file
SEE ALSO
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