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Creating a Distribution Function
Because the number of users is too large, you decide to distribute the entries
according to the first letter of each user's last name, assigning each letter to a
separate database. To do this, you need to create your own distribution function.
Your function determines how each operation received by the
routed to the database containing the information for a particular user.
Once you have distributed entries, you cannot redistribute them. The following
restrictions apply:
•
You cannot change your distribution function once you have deployed entry
distribution.
•
You cannot use the LDAP
modification would cause them to be distributed into a different database.
•
You cannot use the
them to be distributed into a different database.
For example, if you distribute entries according to their telephone number, you
cannot change the telephone number attribute of an entry without breaking
entry distribution.
•
Once you have deployed entry distribution you cannot add more databases.
Creating a Distribution Function
Using the distribution function, you can set a suffix to have any number of
database pointers. This allows you to distribute requests made to a suffix over a
number of databases.
For example, the entry for the
dn: cn="o=example.com", cn=mapping tree, cn=config
objectclass: top
objectclass: extensibleObject
nsslapd-backend: example.com database A-M
nsslapd-backend: example.com database N-Z
When the suffix receives a request from a client, it uses the distribution function to
determine which database services the operation. The plug-in consists of a function
and a library. This function and library are part of the entry for the
suffix and appear as follows:
nsslapd-distribution-plugin: /path/to/a/shared/library
nsslapd-distribution-funct: distribution-function-name
148
Netscape Directory Server Plug-In Programmer's Guide • December 2003
operation to rename entries if the
modrdn
operation to change entries if that would cause
ldapmodify
o=example.com
ou=users
suffix appears as follows:
o=example.com
suffix is
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