1 .TH SLAPD-BDB 5 "RELEASEDATE" "OpenLDAP LDVERSION"
2 .\" Copyright 1998-2007 The OpenLDAP Foundation All Rights Reserved.
3 .\" Copying restrictions apply. See COPYRIGHT/LICENSE.
6 slapd-bdb, slapd-hdb \- Berkeley DB backends to slapd
10 The \fBbdb\fP backend to
12 is the recommended primary backend for a normal
15 It uses the Oracle Berkeley DB (BDB) package to store data.
16 It makes extensive use of indexing and caching to speed data access.
18 \fBhdb\fP is a variant of the \fBbdb\fP backend that uses a
20 layout which supports subtree renames. It is otherwise identical to
21 the \fBbdb\fP behavior, and all the same configuration options apply.
23 It is noted that these options are intended to complement
24 Berkeley DB configuration options set in the environment's
26 file. See Berkeley DB documentation for details on
28 configuration options.
29 Where there is overlap, settings in
35 options apply to the \fBbdb\fP and \fBhdb\fP backend database.
36 That is, they must follow a "database bdb" or "database hdb" line and
37 come before any subsequent "backend" or "database" lines.
38 Other database options are described in the
42 .BI cachesize \ <integer>
43 Specify the size in entries of the in-memory entry cache maintained
44 by the \fBbdb\fP or \fBhdb\fP backend database instance.
45 The default is 1000 entries.
47 .BI cachefree \ <integer>
48 Specify the number of entries to free from the entry cache when the
49 cache reaches the \fBcachesize\fP limit.
50 The default is 1 entry.
52 .BI checkpoint \ <kbyte>\ <min>
53 Specify the frequency for checkpointing the database transaction log.
54 A checkpoint operation flushes the database buffers to disk and writes
55 a checkpoint record in the log.
56 The checkpoint will occur if either \fI<kbyte>\fP data has been written or
57 \fI<min>\fP minutes have passed since the last checkpoint.
58 Both arguments default to zero, in which case they are ignored. When
59 the \fI<min>\fP argument is non-zero, an internal task will run every
60 \fI<min>\fP minutes to perform the checkpoint.
61 See the Berkeley DB reference guide for more details.
63 .BI dbconfig \ <Berkeley\-DB\-setting>
64 Specify a configuration directive to be placed in the
66 file of the database directory. The
68 directive is just a convenience
69 to allow all necessary configuration to be set in the
72 The options set using this directive will only be written to the
74 file if no such file existed at server startup time, otherwise
75 they are completely ignored. This allows one
76 to set initial values without overwriting/destroying a
78 file that was already customized through other means.
79 This directive may be specified multiple times, as needed.
83 dbconfig set_cachesize 0 1048576 0
84 dbconfig set_lg_bsize 2097152
89 Specify that on-disk database contents should not be immediately
90 synchronized with in memory changes.
91 Enabling this option may improve performance at the expense of data
93 See the Berkeley DB reference guide for more details.
95 .BI directory \ <directory>
96 Specify the directory where the BDB files containing this database and
97 associated indexes live.
98 A separate directory must be specified for each database.
100 .BR LOCALSTATEDIR/openldap-data .
103 Allow reads of modified but not yet committed data.
104 Usually transactions are isolated to prevent other operations from
105 accessing uncommitted data.
106 This option may improve performance, but may also return inconsistent
107 results if the data comes from a transaction that is later aborted.
108 In this case, the modified data is discarded and a subsequent search
109 will return a different result.
111 .BI dncachesize \ <integer>
112 Specify the maximum number of DNs in the in-memory DN cache. The
113 default is twice the \fBcachesize\fP. Ideally this cache should be
114 large enough to contain the DNs of every entry in the database.
116 .BI idlcachesize \ <integer>
117 Specify the size of the in-memory index cache, in index slots. The
118 default is zero. A larger value will speed up frequent searches of
119 indexed entries. An \fBhdb\fP database needs a large \fBidlcachesize\fP
120 for good search performance, typically three times the
125 \fBindex \fR{\fI<attrlist>\fR|\fBdefault\fR} [\fBpres\fR,\fBeq\fR,\fBapprox\fR,\fBsub\fR,\fI<special>\fR]
126 Specify the indexes to maintain for the given attribute (or
128 Some attributes only support a subset of indexes.
129 If only an \fI<attr>\fP is given, the indices specified for \fBdefault\fR
131 Note that setting a default does not imply that all attributes will be
132 indexed. Also, for best performance, an
134 index should always be configured for the
138 A number of special index parameters may be specified.
141 can be decomposed into
148 may be specified to disallow use of this index by language subtypes.
151 may be specified to disallow use of this index by named subtypes.
152 Note: changing \fBindex\fP settings in
154 requires rebuilding indices, see
156 changing \fBindex\fP settings
157 dynamically by LDAPModifying "cn=config" automatically causes rebuilding
158 of the indices online in a background task.
163 to index one attribute at a time. By default, all indexed
164 attributes in an entry are processed at the same time. With this option,
165 each indexed attribute is processed individually, using multiple passes
166 through the entire database. This option improves
169 when the database size exceeds the \fBdbcache\fP size. When the \fBdbcache\fP is
170 large enough, this option is not needed and will decrease performance.
173 performs full indexing and so a separate
175 run is not needed. With this option,
181 .BR lockdetect \ { oldest | youngest | fewest | random | default }
182 Specify which transaction to abort when a deadlock is detected.
187 Specify the file protection mode that newly created database
188 index files should have.
191 .BI searchstack \ <depth>
192 Specify the depth of the stack used for search filter evaluation.
193 Search filters are evaluated on a stack to accommodate nested AND / OR
194 clauses. An individual stack is assigned to each server thread.
195 The depth of the stack determines how complex a filter can be
196 evaluated without requiring any additional memory allocation. Filters that
197 are nested deeper than the search stack depth will cause a separate
198 stack to be allocated for that particular search operation. These
199 allocations can have a major negative impact on server performance,
200 but specifying too much stack will also consume a great deal of memory.
201 Each search stack uses 512K bytes per level. The default stack depth
202 is 16, thus 8MB per thread is used.
204 .BI shm_key \ <integer>
205 Specify a key for a shared memory BDB environment. By default the
206 BDB environment uses memory mapped files. If a non-zero value is
207 specified, it will be used as the key to identify a shared memory
208 region that will house the environment.
214 backends honor access control semantics as indicated in
215 .BR slapd.access (5).
224 Berkeley DB configuration file
231 Berkeley DB documentation.
234 Originally begun by Kurt Zeilenga. Caching mechanisms originally designed
235 by Jong-Hyuk Choi. Completion and subsequent work, as well as
236 back-hdb, by Howard Chu.
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