slapd-ndb - MySQL NDB backend to slapd
backend to slapd
(8) uses the MySQL Cluster package to
store data, through its NDB API. It provides fault tolerance with extreme
scalability, along with a degree of SQL compatibility.
This backend is designed to store LDAP information using tables that are also
visible from SQL. It uses a higher level SQL API for creating these tables,
while using the low level NDB API for storing and retrieving the data within
these tables. The NDB Cluster engine allows data to be partitioned across
multiple data nodes, and this backend allows multiple slapd instances to
operate against a given database concurrently.
The general approach is to use distinct tables for each LDAP object class.
Entries comprised of multiple object classes will have their data spread
across multiple tables. The data tables use a 64 bit entryID as their primary
key. The DIT hierarchy is maintained in a separate table, which maps DNs to
This backend is experimental. While intended to be a general-purpose backend, it
is currently missing a number of common LDAP features. See the TODO
file in the source directory for details.
options apply to the ndb
backend database. That
is, they must follow a "database ndb" line and come before any
subsequent "backend" or "database" lines. Other database
options are described in the slapd.conf
(5) manual page.
- dbhost <hostname>
- The name or IP address of the host running the MySQL
server. The default is "localhost". On Unix systems, the
connection to a local server is made using a Unix Domain socket, whose
path is specified using the dbsocket directive.
- dbuser <username>
- The MySQL login ID to use when connecting to the MySQL
server. The chosen user must have sufficient privileges to manipulate the
SQL tables in the target database.
- dbpasswd <password>
- The password for the dbuser.
- dbname <database name>
- The name of the MySQL database to use.
- dbport <port>
- The port number to use for the TCP connection to the MySQL
- dbsocket <path>
- The socket to be used for connecting to a local MySQL
- dbflag <integer>
- Client flags for the MySQL session. See the MySQL
documentation for details.
- dbconnect <connectstring>
- The name or IP address of the host running the cluster
manager. The default is "localhost".
- dbconnections <integer>
- The number of cluster connections to establish. Using up to
4 may improve performance under heavier load. The default is 1.
- attrlen <attribute> <length>
- Specify the column length to use for a particular
attribute. LDAP attributes are stored in individual columns of the SQL
tables. The maximum column lengths for each column must be specified when
creating these tables. If a length constraint was specified in the
attribute's LDAP schema definition, that value will be used by default. If
the schema didn't specify a constraint, the default is 128 bytes.
Currently the maximum is 1024.
- index <attr[,attr...]>
- Specify a list of attributes for which indexing should be
maintained. Currently there is no support for substring indexing; a single
index structure provides presence, equality, and inequality indexing for
the specified attributes.
- attrset <set> <attrs>
- Specify a list of attributes to be treated as an attribute
set. This directive creates a table named set which will contain
all of the listed attributes. Ordinarily an attribute resides in a table
named by an object class that uses the attribute. However, attributes are
only allowed to appear in a single table. For attributes that are derived
from an inherited object class definition, the attribute will only be
stored in the superior class's table. Attribute sets should be defined for
any attributes that are used in multiple unrelated object classes, i.e.,
classes that are not connected by a simple inheritance chain.
backend honors most access control semantics as indicated in
- default slapd configuration file
(8), MySQL Cluster
Howard Chu, with assistance from Johan Andersson et al @ MySQL.