Occasionally, applications want to read back the data that they just wrote.
If a modification requested to a shadow server was silently chained to its
-producer, an immediate read could result in receiving data not yet sync'ed.
+producer, an immediate read could result in receiving data not yet synchronized.
In those cases, clients should use the {{B:dontusecopy}} control to ensure
they are directed to the authoritative source for that piece of data.
H3: Overview
-This overlay implements the provider-side support for syncrepl
-replication, including persistent search functionality
-
+This overlay implements the provider-side support for the LDAP Content Synchronization
+({{REF:RFC4533}}) as well as syncrepl replication support, including persistent search functionality.
H3: Sync Provider Configuration
+There is very little configuration needed for this overlay, in fact for many situations merely loading
+the overlay will suffice.
+
+However, because the overlay creates a contextCSN attribute in the root entry of the database which is
+updated for every write operation performed against the database and only updated in memory, it is
+recommended to configure a checkpoint so that the contextCSN is written into the underlying database to
+minimize recovery time after an unclean shutdown:
+
+> overlay syncprov
+> syncprov-checkpoint 100 10
+
+For every 100 operations or 10 minutes, which ever is sooner, the contextCSN will be checkpointed.
+
+The four configuration directives available are {{B:syncprov-checkpoint}}, {{B:syncprov-sessionlog}},
+{{B:syncprov-nopresent}} and {{B:syncprov-reloadhint}} which are covered in the man page discussing
+various other scenarios where this overlay can be used.
H3: Further Information
-{{:slapo-syncprov(5)}}
+The {{:slapo-syncprov(5)}} man page and the {{SECT:Configuring the different replication types}} section
H2: Translucent Proxy
H3: Overview
-This overlay can be used with a backend database such as slapd-bdb (5)
+This overlay can be used with a backend database such as {{slapd-bdb(5)}}
to enforce the uniqueness of some or all attributes within a subtree.
H3: Attribute Uniqueness Configuration
+This overlay is only effective on new data from the point the overlay is enabled. To
+check uniqueness for existing data, you can export and import your data again via the
+LDAP Add operation, which will not be suitable for large amounts of data, unlike {{B:slapcat}}.
+
+For the following example, if uniqueness were enforced for the {{B:mail}} attribute,
+the subtree would be searched for any other records which also have a {{B:mail}} attribute
+containing the same value presented with an {{B:add}}, {{B:modify}} or {{B:modrdn}} operation
+which are unique within the configured scope. If any are found, the request is rejected.
+
+Note: If no attributes are specified, for example {{B:ldap:///??sub?}}, then the URI applies to all non-operational attributes. However,
+the keyword {{B:ignore}} can be specified to exclude certain non-operational attributes.
+
+To search at the base dn of the current backend database ensuring uniqueness of the {{B:mail}}
+attribute, we simply add the following configuration:
+
+> overlay unique
+> unique_uri ldap:///?mail?sub?
+
+For an existing entry of:
+
+> dn: cn=gavin,dc=suretecsystems,dc=com
+> objectClass: top
+> objectClass: inetorgperson
+> cn: gavin
+> sn: henry
+> mail: ghenry@suretecsystems.com
+
+and we then try to add a new entry of:
+
+> dn: cn=robert,dc=suretecsystems,dc=com
+> objectClass: top
+> objectClass: inetorgperson
+> cn: robert
+> sn: jones
+> mail: ghenry@suretecsystems.com
+
+would result in an error like so:
+
+> adding new entry "cn=robert,dc=example,dc=com"
+> ldap_add: Constraint violation (19)
+> additional info: some attributes not unique
+
+The overlay can have multiple URIs specified within a domain, allowing complex
+selections of objects and also have multiple {{B:unique_uri}} statements or
+{{B:olcUniqueURI}} attributes which will create independent domains.
+
+For more information and details about the {{B:strict}} and {{B:ignore}} keywords,
+please see the {{:slapo-unique(5)}} man page.
H3: Further Information
projects / openldap / commitdiff