slapd-bdb, slapd-hdb - BDB backends to slapd

/etc/ldap/slapd.conf

The BDB backend to 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.

"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.

These 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 slapd.conf(5) manual page.

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.

checkpoint <kbyte> <min>

Specify the frequency for checkpointing the database transaction log upon updating of the database. A checkpoint flushes the database buffers to disk and writes a checkpoint record in the log. Upon a database update, a 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. Note: checkpointing by this directive occurs only upon execution of a database update. If one desires checkpointing to occur otherwise, db_checkpoint(1) or some other external process should be used to cause a database checkpoint to be taken. See the Berkeley DB reference guide for more details.

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.

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 /var/openldap-data.

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.

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.

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 subinitial, 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 requires rebuilding indices, see slapindex(8).

lockdetect {oldest|youngest|fewest|random|default}

Specify which transaction to abort when a deadlock is detected. The default is the same as random.

mode <integer>

Specify the file protection mode that newly created database index files should have. The default is 0600.

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.

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.

sessionlog <sid> <limit>

Specify a session log store for the syncrepl replication provider server. The session log store contains information on the entries that have been scoped out of the provider replication content identified by <sid>. The number of entries in the session log store is limited by <limit>. Excessive entries are removed from the store in the FIFO order. Both <sid> and <limit> are non-negative integers. <sid> has no more than three decimal digits. Refer to the "OpenLDAP Administrator's Guide" for detailed information on setting up a replicated slapd directory service using the syncrepl replication engine and the session log store.

/etc/ldap/slapd.conf

default slapd configuration file

DB_CONFIG

Berkeley DB configuration file

slapd.conf(5), slapd(8), slapadd(8), slapcat(8), slapindex(8), Berkeley DB documentation.