Commit 918173fd authored by Howard Chu's avatar Howard Chu Committed by Quanah Gibson-Mount
Browse files

ITS#7590 tweak bdb/hdb/mdb notes

parent 8871e28f
......@@ -23,18 +23,22 @@ H2: Berkeley DB Backends
H3: Overview
The {{bdb}} backend to {{slapd}}(8) is the recommended primary backend for a
The {{hdb}} backend to {{slapd}}(8) is the recommended primary backend for a
normal {{slapd}} database. It uses the Oracle Berkeley DB ({{TERM:BDB}})
package to store data. It makes extensive use of indexing and caching
(see the {{SECT:Tuning}} section) 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.
{{hdb}} is a variant of the original {{bdb}} backend which was first written for use with BDB.
{{hdb}} uses a hierarchical database layout which supports subtree renames.
It is otherwise identical to the {{bdb}}
behavior, and all the same configuration options apply.
Note: An {{hdb}} database needs a large {{idlcachesize}} for good search performance,
typically three times the {{cachesize}} (entry cache size) or larger.
Note: The {{hdb}} backend has superseded the {{bdb}} backend, and both will
soon be deprecated in favor of the new {{mdb}} backend. See below.
H3: back-bdb/back-hdb Configuration
MORE LATER
......@@ -187,13 +191,14 @@ H3: Further Information
{{slapd-ldif}}(5)
H2: MDB
H2: LMDB
H3: Overview
The {{mdb}} backend to {{slapd}}(8) is the upcoming primary backend for a
normal {{slapd}} database. It uses OpenLDAP's own Memory-Mapped Database ({{TERM:MDB}})
normal {{slapd}} database. It uses OpenLDAP's own
Lightning Memory-Mapped Database ({{TERM:LMDB}})
library to store data and is intended to replace the Berkeley DB backends.
It supports indexing like the BDB backends, but it uses no caching and requires
......@@ -202,7 +207,7 @@ fully hierarchical and supports subtree renames in constant time.
H3: back-mdb Configuration
Unlike the BDB backends, the MDB backend can be instantiated with very few
Unlike the BDB backends, the {{mdb}} backend can be instantiated with very few
configuration lines:
> include ./schema/core.schema
......@@ -214,7 +219,7 @@ configuration lines:
> rootpw mdb
> maxsize 1073741824
In addition to the usual parameters that a minimal configuration requires, the MDB
In addition to the usual parameters that a minimal configuration requires, the {{mdb}}
backend requires a maximum size to be set. This should be the largest that
the database is ever anticipated to grow (in bytes). The filesystem must also
provide enough free space to accommodate this size.
......
......@@ -28,8 +28,8 @@ H3: Memory
Scale your cache to use available memory and increase system memory if you can.
See {{SECT:Caching}} for BDB cache tuning hints.
Note that MDB uses no cache of its own and has no tuning options, so the Caching
section can be ignored when using MDB.
Note that LMDB uses no cache of its own and has no tuning options, so the Caching
section can be ignored when using LMDB.
H3: Disks
......
......@@ -223,8 +223,8 @@ LDAP|Lightweight Directory Access Protocol
LDAP Sync|LDAP Content Synchronization
LDAPv3|LDAP, version 3
LDIF|LDAP Data Interchange Format
LMDB|Lightning Memory-Mapped Database
MD5|Message Digest 5
MDB|Memory-Mapped Database
MIB|Management Information Base
MODDN|Modify DN
MODRDN|Modify RDN
......
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