Re: Modifying existing schema definition without reimporting data ?

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 04:43 AM 1/5/2007, Heinzmann, Robert wrote:
>Hello, 
>
>is it possible to change Schema definitions on openldap servers without
>recreating the backend ? 

The general answer is: it depends.  It depends on the
precise change is being made, the version of software
being used, and couple possibly depend on configuration
details (such as which backends are being used).

>Background: We have a ldap server (or multiple replicated LDAP servers)
>and have a certain attribute in the schema defitnion that is currently
>defined as "single value". It's the MAC address for clients used for
>X802.1 auth. The attribute is part oif the user object used for logins.
>Now it's possible, that users have multiple MAC addresses. We want to
>add multiple MAC addresses to that list, so we must chnage the attribute
>type from single to multiple values (sorry, I don't know the exact name
>of the defintion statement). 
>
>Would this be possible by doing the following: 
>
>stop ldap slave server 
>change schema defintion for MAC address attribute from single to
>multivalue
>Start ldap slave again
>
>stop ldap master  
>change schema defintion for MAC address attribute from single to
>multivalue
>Start ldap master 

Ignoring impact to other software (which is something for
discussion elsewhere, e.g., on a general LDAP list), one can, with
the current release, database backends, and overlays, removing a
singled-value constraint is, I believe, possible without reloading
the database.  Whether it possible with future releases, backends,
and/or overlays is, well, another matter.

>Is changing the schema definion generally possible for changes other
>then singlevalue->multivalue - e.g. add another attribute or modify
>other things ? 

I would say its generally not possible.  That is, unless you know
its okay with the particular software/configuration you have, you
should assume its not okay.

-- Kurt