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ITS#9613, ITS#9614 - Document multival, idlexp, and maxentrysize options to slapd-mdb

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multival, idlexp, and maxentrysize are all new options as of OpenLDAP 2.5 that were missing from the admin guide.  Add these options and additional information beyond what is found in the man pages as appropriate.

Also fixed some discrepencies between the slapd.conf and slapd-config admin guide sections on the Database backends as well as missing information in that section.
This commit is contained in:
Quanah Gibson-Mount 2021-07-23 21:27:18 +00:00
parent cb5ba6781f
commit 9da2307d71
2 changed files with 135 additions and 10 deletions
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73
doc/guide/admin/slapdconf2.sdf
View File

@ -361,27 +361,31 @@ supported backend types listed in Table 5.2.
!block table; align=Center; coltags="EX,N"; \
title="Table 5.2: Database Backends"
Types Description
asyncmeta Asynchronous Metadirectory backend
config Slapd configuration backend
dnssrv DNS SRV backend
ldap Lightweight Directory Access Protocol (Proxy) backend
ldif Lightweight Data Interchange Format backend
mdb Memory-Mapped DB backend
meta Meta Directory backend
meta Metadirectory backend
monitor Monitor backend
ndb MySQL NDB backend
null Null backend
passwd Provides read-only access to {{passwd}}(5)
perl Perl Programmable backend
shell Shell (extern program) backend
relay Relay backend
sock Socket backend
sql SQL Programmable backend
wt WiredTiger backend
!endblock
\Example:
> olcBackend: mdb
There are no other directives defined for this entry. Specific backend
types may define additional attributes for their particular use but so
far none have ever been defined. As such, these directives usually do
not appear in any actual configurations.
This marks the beginning of a new {{TERM:MDB}} backend
definition. At present, only back-mdb implements any options
of this type, so this setting is not needed for any other backends.
H4: Sample Entry
@ -389,6 +393,7 @@ H4: Sample Entry
> dn: olcBackend=mdb,cn=config
> objectClass: olcBackendConfig
> olcBackend: mdb
> olcBkMdbIdlExp: 16
H3: Database-specific Directives
@ -724,6 +729,33 @@ H4: Sample Entries
>olcRootDN: cn=Manager,dc=example,dc=com
H3: MDB Backend Directives
Directives in this category only apply to the {{TERM:MDB}}
database backend. They will apply to all "database mdb"
instances in the configuration. For a complete reference
of MDB backend configuration directives, see {{slapd-mdb}}(5).
H4: olcBkMdbIdlExp <exponent>
Specify a power of 2 for the maximum size of an index slot.
The default is 16, yielding a maximum slot size of 2^16 or 65536.
The specified value must be in the range of 16-31.
This setting helps with the case where certain search filters are
slow to return results due to an index slot having collapsed to a
range value. This occurs when the number of candidate entries that
match the filter for the index slot exceed the configured slot size.
If this setting is decreased on a server with existing {{TERM:MDB}}
databases, each db will immediately need its indicies to be rebuilt
while slapd is offline with the "slapindex -q -t" command.
If this setting is increased on a server with existing {{TERM:MDB}}
databases, each db will need its indices rebuilt to take advantage
of the change for indices that have already been converted to ranges.
H3: MDB Database Directives
Directives in this category apply to the {{TERM:MDB}}
@ -849,6 +881,13 @@ stopped before the index task completes, indexing will have to be
manually completed using the slapindex tool.
H4: olcDbMaxEntrySize: <bytes>
Specify the maximum size of an entry in bytes. Attempts to store
an entry larger than this size will be rejected with the error
LDAP_ADMINLIMIT_EXCEEDED. The default is 0, which is unlimited.
H4: olcDbMaxReaders: <integer>
This directive specifies the maximum number of threads that may have
@ -880,6 +919,28 @@ created database index files should have. This can be in the form
> olcDbMode: 0600
H4: olcDbMultival: { <attrlist> | default } <integer> hi,<integer> lo
Specify the number of values for which a multivalued attribute is
stored in a separate table. Normally entries are stored as a single
blob inside the database. When an entry gets very large or contains
attributes with a very large number of values, modifications on that
entry may get very slow. Splitting the large attributes out to a separate
table can improve the performance of modification operations.
The threshold is specified as a pair of integers. If the number of
values exceeds the hi threshold the values will be split out. If
a modification deletes enough values to bring an attribute below
the lo threshold the values will be removed from the separate
table and merged back into the main entry blob.
The threshold can be set for a specific list of attributes, or
the default can be configured for all other attributes.
The default value for both hi and lo thresholds is UINT_MAX, which keeps
all attributes in the main blob.
In addition to increasing write performance of operations the use of
multival can also decrease fragmentation of the primary {{TERM:MDB}} database.
H4: olcDbRtxnsize: <entries>
This directive specifies the maximum number of entries to process in a single

72
doc/guide/admin/slapdconfig.sdf
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@ -261,23 +261,32 @@ supported backend types listed in Table 6.2.
!block table; align=Center; coltags="EX,N"; \
title="Table 6.2: Database Backends"
Types Description
asyncmeta Asynchronous Metadirectory backend
config Slapd configuration backend
dnssrv DNS SRV backend
ldap Lightweight Directory Access Protocol (Proxy) backend
ldif Lightweight Data Interchange Format backend
mdb Memory-Mapped DB backend
meta Meta Directory backend
meta Metadirectory backend
monitor Monitor backend
ndb MySQL NDB backend
null Null backend
passwd Provides read-only access to {{passwd}}(5)
perl Perl Programmable backend
shell Shell (extern program) backend
relay Relay backend
sock Socket backend
sql SQL Programmable backend
wt WiredTiger backend
!endblock
\Example:
> backend mdb
> idlexp 16
This marks the beginning of a new {{TERM:MDB}} backend
definition.
definition. At present, only back-mdb implements any options
of this type, so this setting is not needed for any other backends.
H3: General Database Directives
@ -575,6 +584,33 @@ If specified multiple times, each {{TERM:URL}} is provided.
> updateref ldap://provider.example.net
H3: MDB Backend Directives
Directives in this category only apply to the {{TERM:MDB}}
database backend. They will apply to all "database mdb"
instances in the configuration. For a complete reference
of MDB backend configuration directives, see {{slapd-mdb}}(5).
H4: idlexp <exponent>
Specify a power of 2 for the maximum size of an index slot.
The default is 16, yielding a maximum slot size of 2^16 or 65536.
The specified value must be in the range of 16-31.
This setting helps with the case where certain search filters are
slow to return results due to an index slot having collapsed to a
range value. This occurs when the number of candidate entries that
match the filter for the index slot exceed the configured slot size.
If this setting is decreased on a server with existing {{TERM:MDB}}
databases, each db will immediately need its indicies to be rebuilt
while slapd is offline with the "slapindex -q -t" command.
If this setting is increased on a server with existing {{TERM:MDB}}
databases, each db will need its indices rebuilt to take advantage
of the change for indices that have already been converted to ranges.
H3: MDB Database Directives
Directives in this category only apply to the {{TERM:MDB}}
@ -583,7 +619,6 @@ That is, they must follow a "database mdb" line
and come before any subsequent "backend" or "database" lines.
For a complete reference of MDB configuration directives, see {{slapd-mdb}}(5).
H4: directory <directory>
This directive specifies the directory where the MDB files
@ -697,6 +732,13 @@ normal use of the directory. Most applications don't use presence
searches, so usually presence indexing is not very useful.
H4: maxentrysize: <bytes>
Specify the maximum size of an entry in bytes. Attempts to store
an entry larger than this size will be rejected with the error
LDAP_ADMINLIMIT_EXCEEDED. The default is 0, which is unlimited.
H4: maxreaders: <integer>
This directive specifies the maximum number of threads that may have
@ -728,6 +770,28 @@ created database index files should have. This can be in the form
> mode: 0600
H4: multival: { <attrlist> | default } <integer> hi,<integer> lo
Specify the number of values for which a multivalued attribute is
stored in a separate table. Normally entries are stored as a single
blob inside the database. When an entry gets very large or contains
attributes with a very large number of values, modifications on that
entry may get very slow. Splitting the large attributes out to a separate
table can improve the performance of modification operations.
The threshold is specified as a pair of integers. If the number of
values exceeds the hi threshold the values will be split out. If
a modification deletes enough values to bring an attribute below
the lo threshold the values will be removed from the separate
table and merged back into the main entry blob.
The threshold can be set for a specific list of attributes, or
the default can be configured for all other attributes.
The default value for both hi and lo thresholds is UINT_MAX, which keeps
all attributes in the main blob.
In addition to increasing write performance of operations the use of
multival can also decrease fragmentation of the primary {{TERM:MDB}} database.
H4: rtxnsize: <entries>
This directive specifies the maximum number of entries to process in a single