Re: overlay order important and not documented?

[Howard Chu <hyc@symas.com>]

Francis Swasey wrote:
> On 3/16/07 2:58 PM, Pierangelo Masarati wrote:
> > Howard Chu wrote:
> >
> > > Yes, and that's probably the cleanest behavior. The overlay stack is 
> > > only supposed to be executed completely for operations that came from 
> > > the frontend. Any overlay on the stack should go through any other 
> > > overlays below it, but not through any that are above it.
> >
> > However, the accesslog would be unusable for replication; I see the 
> > point: refint should be present on the shadow as well, and do locally 
> > refint modifications, right?
>
> I disagree!  Since the only modifications that arrive at the replicas 
> (or shadows) came from the master.  I should be able to set up the 
> overlays for unique and refint on the master and be done with it.  I 
> should not have to waste the cpu cycles on each of the replicas to 
> perform the same operations that were already figured out and done on 
> the master ldap server.
There are valid reasons to do it either way - for one thing, 
instantiating the refint overlay on the replicas reduces network 
traffic. Also if you have a hot standby setup you want the replicas to 
be configured as nearly identically to the master as possible. (In 
mirrormode the replica and the master should be identical, or mirror 
image, anyway.)
--
  -- Howard Chu
  Chief Architect, Symas Corp.  http://www.symas.com
  Director, Highland Sun        http://highlandsun.com/hyc
  Chief Architect, OpenLDAP     http://www.openldap.org/project/