Re: (ITS#6641) Syncrepl failure with 'overlay unique'

[hyc@symas.com]

andrew.findlay@skills-1st.co.uk wrote:
> Full_Name: Andrew Findlay
> Version: 2.4.23
> OS: SLES 10.3 x86_64
> URL: ftp://ftp.openldap.org/incoming/
> Submission from: (NULL) (88.97.25.132)
>
>
> The attribute uniqueness overlay can cause syncrepl to jam up.
> Consider this case:

> The obvious answer is for syncrepl to bypass all data checks, as the supplier
> server should have already enforced them. The problem with that is that clients
> could see data that breaks the rules if they query while syncrepl is running
> (unless the refresh phase is handled as a single transaction and thus isolated
> from clients until it is complete).

We've talked about doing this isolation in the first refresh upon slapd 
startup. That might still be a good idea.

Doing it on every refresh seems far more problematic, because without some 
type of multi-version concurrency control, that means making the server 
non-responsive until the refresh completes.

-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/