Re: Updating a private schema (cn=config)?

[Andrzej Jan Taramina <andrzej@chaeron.com>]

Howard replied:

> This was just discussed on -technical as well. You can delete 
> individual 
> schema elements using ldapmodify. You cannot delete entire cn=config 
> entries 
> (using ldapdelete). There are no plans to change this behavior for 
> schema in 
> the future.

Using ldapmodify for individual entries is painful in the extreme, since each entry only has a single
attribute...basically a monster string with all the schema constraints in it.

> > > What about any entries that depend on the schema? Will they be
> affected...
>
> The answer is "it depends"...

Depends on what?  I would really like to know what OpenLDAP does internally by way of linking entries back to their
schema definitions, and when such linkages are used.

> In general, once you start using a schema, you're stuck with it. 
> (Which is one 
> reason why ldapdelete for schema entries will never be implemented.) 

That makes no sense. Checking to see if there are entries that depend on the schema before attempting the delete and
declining the delete if there are such entries makes sense. A blanket refusal to do such a delete is inappropriate, IMO.

> You can 
> fine tune individual elements of it (alter definitions, add/remove 
> definitions), but there are issues that are still being worked on.
> See ITS#5540 for one of the problems still in progress.

Not receiving any practical tips on how to update a whole private schema in one fell swoop, here's what I did and what
seemed to work fine:

1) Delete all entries that depend on the schema you need to updated (used ldapmodify)
2) Shut down slapd
3) sudo rm /etc/ldap/slapd.d/cn=config/cn=schema/cn={4}myschema.ldif.  Change the last part to refer to your custom
schema. I'm using latest Ubuntu Intrepid OpenLDAP, so the location of the cn=config dir may be different for you.
4) Restart slapd
5) Use ldapadd to add your modified schema
6) Use ldapadd to re-add your schema entries.

This worked well for me, since I have entry deletion/creation ldif declarations that are automatically generated by our
application....no problems detected so far.

Anyone see any issues with this approach?

Seems to me that the whole alternate configuration approach using cn=config in the database is still very much a work in
progress.

--
Andrzej Taramina
Chaeron Corporation: Enterprise System Solutions
http://www.chaeron.com