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More updates for the BDB config section
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Howard Chu
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@ -746,71 +746,92 @@ containing the database and associated indices live.
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> olcDbDirectory: /usr/local/var/openldap-data
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H4: Sample Entry
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>dn: olcDatabase=bdb,cn=config
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>objectClass: olcDatabaseConfig
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>objectClass: olcBdbConfig
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>olcDatabase: bdb
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>olcSuffix: "dc=example,dc=com"
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>olcDbDirectory: /usr/local/var/openldap-data
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H3: LDBM Database Directives
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Directives in this category only apply to a {{TERM:LDBM}} database.
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That is, they must follow a "database ldbm" line and come before
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any subsequent "backend" or "database" line. For a complete reference
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of LDBM configuration directives, see {{slapd-ldbm}}(5).
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H4: cachesize <integer>
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H4: olcDbCachesize: <integer>
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This directive specifies the size in entries of the in-memory
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cache maintained by the LDBM backend database instance.
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cache maintained by the BDB backend database instance.
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\Default:
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> cachesize 1000
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> olcDbCachesize: 1000
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H4: dbcachesize <integer>
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H4: olcDbCheckpoint: <kbyte> <min>
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This directive specifies the size in bytes of the in-memory cache
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associated with each open index file. If not supported by the
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underlying database method, this directive is ignored without
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comment. Increasing this number uses more memory but can
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cause a dramatic performance increase, especially during
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modifies or when building indices.
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This directive specifies how often to checkpoint the BDB transaction log.
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A checkpoint operation flushes the database buffers to disk and writes a
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checkpoint record in the log.
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The checkpoint will occur if either <kbyte> data has been written or
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<min> minutes have passed since the last checkpont. Both arguments default
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to zero, in which case they are ignored. When the <min> argument is
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non-zero, an internal task will run every <min> minutes to perform the
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checkpoint. See the Berkeley DB reference guide for more details.
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\Default:
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\Example:
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> dbcachesize 100000
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> olcDbCheckpoint: 1024 10
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H4: dbnolocking
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H4: olcDbConfig: <DB_CONFIG setting>
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This option, if present, disables database locking.
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Enabling this option may improve performance at the expense
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of data security.
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This attribute specifies a configuration directive to be placed in the
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{{EX:DB_CONFIG}} file of the database directory. At server startup time, if
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no such file exists yet, the {{EX:DB_CONFIG}} file will be created and the
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settings in this attribute will be written to it. If the file exists,
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its contents will be read and displayed in this attribute. The attribute
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is multi-valued, to accomodate multiple configuration directives. No default
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is provided, but it is essential to use proper settings here to get the
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best server performance.
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\Example:
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> olcDbConfig: set_cachesize 0 10485760 0
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> olcDbConfig: set_lg_bsize 2097512
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> olcDbConfig: set_lg_dir /var/tmp/bdb-log
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> olcDbConfig: set_flags DB_LOG_AUTOREMOVE
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In this example, the BDB cache is set to 10MB, the BDB transaction log
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buffer size is set to 2MB, and the transaction log files are to be stored
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in the /var/tmp/bdb-log directory. Also a flag is set to tell BDB to
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delete transaction log files as soon as their contents have been
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checkpointed and they are no longer needed. Without this setting the
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transaction log files will continue to accumulate until some other
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cleanup procedure removes them. See the SleepyCat documentation for the
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{{EX:db_archive}} command for details.
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Ideally the BDB cache must be
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at least as large as the working set of the database, the log buffer size
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should be large enough to accomodate most transactions without overflowing,
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and the log directory must be on a separate physical disk from the main
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database files. And both the database directory and the log directory
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should be separate from disks used for regular system activities such as
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the root, boot, or swap filesystems. See the FAQ-o-Matic and the SleepyCat
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documentation for more details.
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H4: dbnosync
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H4: olcDbNosync: <TRUE|FALSE>
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This option causes on-disk database contents to not be immediately
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synchronized with in memory changes upon change. Enabling this option
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may improve performance at the expense of data integrity.
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synchronized with in memory changes upon change. Setting this option
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to TRUE may improve performance at the expense of data integrity. This
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directive has the same effect as using
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> olcDbConfig: set_flags DB_TXN_NOSYNC
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H4: directory <directory>
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H4: olcDbIDLcacheSize: <integer>
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This directive specifies the directory where the LDBM files
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containing the database and associated indices live.
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Specify the size of the in-memory index cache, in index slots. The
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default is zero. A larger value will speed up frequent searches of
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indexed entries. The optimal size will depend on the data and search
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characteristics of the database, but using a number three times
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the entry cache size is a good starting point.
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\Default:
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\Example:
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> directory /usr/local/var/openldap-data
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> olcDbIDLcacheSize: 3000
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H4: index {<attrlist> | default} [pres,eq,approx,sub,none]
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H4: olcDbIndex: {<attrlist> | default} [pres,eq,approx,sub,none]
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This directive specifies the indices to maintain for the given
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attribute. If only an {{EX:<attrlist>}} is given, the default
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@ -818,10 +839,10 @@ indices are maintained.
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\Example:
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> index default pres,eq
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> index uid
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> index cn,sn pres,eq,sub
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> index objectClass eq
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> olcDbIndex: default pres,eq
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> olcDbIndex: uid
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> olcDbIndex: cn,sn pres,eq,sub
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> olcDbIndex: objectClass eq
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The first line sets the default set of indices to maintain to
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present and equality. The second line causes the default (pres,eq)
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@ -834,20 +855,95 @@ attribute type.
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By default, no indices are maintained. It is generally advised
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that minimally an equality index upon objectClass be maintained.
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> index objectClass eq
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> olcDbindex: objectClass eq
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If this setting is changed while slapd is running, an internal task
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will be run to generate the changed index data. All server operations
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can continue as normal while the indexer does its work. If slapd is
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stopped before the index task completes, indexing will have to be
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manually completed using the slapindex tool.
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H4: olcDbLinearIndex: <TRUE|FALSE>
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H4: mode <integer>
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If this setting is {{EX:TRUE}} slapindex will index one attribute
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at a time. The default settings is {{EX:FALSE}} in which case all
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indexed attributes of an entry are processed at the same time. When
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enabled, each indexed attribute is processed individually, using
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multiple passes through the entire database. This option improves
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slapindex performance when the database size exceeds the BDB cache
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size. When the BDB cache is large enough, this option is not needed
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and will decrease performance. Also by default, slapadd performs
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full indexing and so a separate slapindex run is not needed. With
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this option, slapadd does no indexing and slapindex must be used.
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H4: olcDbMode: <integer>
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This directive specifies the file protection mode that newly
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created database index files should have.
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\Default:
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> mode 0600
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> olcDbMode: 0600
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H4: olcDbSearchStack: <integer>
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Specify the depth of the stack used for search filter evaluation.
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Search filters are evaluated on a stack to accomodate nested {{EX:AND}} /
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{{EX:OR}} clauses. An individual stack is allocated for each server thread.
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The depth of the stack determines how complex a filter can be evaluated
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without requiring any additional memory allocation. Filters that are
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nested deeper than the search stack depth will cause a separate stack to
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be allocated for that particular search operation. These separate allocations
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can have a major negative impact on server performance, but specifying
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too much stack will also consume a great deal of memory. Each search
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uses 512K bytes per level on a 32-bit machine, or 1024K bytes per level
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on a 64-bit machine. The default stack depth is 16, thus 8MB or 16MB
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per thread is used on 32 and 64 bit machines, respectively. Also the
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512KB size of a single stack slot is set by a compile-time constant which
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may be changed if needed; the code must be recompiled for the change
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to take effect.
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\Default:
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> olcDbSearchStack: 16
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H4: olcDbShmKey: <integer>
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Specify a key for a shared memory BDB environment. By default the BDB
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environment uses memory mapped files. If a non-zero value is specified,
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it will be used as the key to identify a shared memory region that will
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house the environment.
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\Example:
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> olcDbShmKey: 42
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H4: Sample Entry
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>dn: olcDatabase=bdb,cn=config
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>objectClass: olcDatabaseConfig
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>objectClass: olcBdbConfig
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>olcDatabase: bdb
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>olcSuffix: "dc=example,dc=com"
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>olcDbDirectory: /usr/local/var/openldap-data
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>olcDbCacheSize: 1000
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>olcDbCheckpoint: 1024 10
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>olcDbConfig: set_cachesize 0 10485760 0
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>olcDbConfig: set_lg_bsize 2097152
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>olcDbConfig: set_lg_dir /var/tmp/bdb-log
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>olcDbConfig: set_flags DB_LOG_AUTOREMOVE
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>olcDbIDLcacheSize: 3000
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>olcDbIndex: objectClass eq
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Note: the remainder of this chapter has not yet been updated to reflect
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the new cn=config mechanisms.
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H2: Access Control
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Access to slapd entries and attributes is controlled by the
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