Re: (ITS#4239) Maintain Replica CSN information without syncrepl in place

[hyc@symas.com]

quanah@stanford.edu wrote:
> Full_Name: Quanah Gibson-Mount
> Version: 2.3.13
> OS: Solaris 8
> URL: ftp://ftp.openldap.org/incoming/
> Submission from: (NULL) (171.66.155.86)
>
>
> This is kind of a feature enhancement request.
>
> Essentially, I've looked at moving from slurpd-> delta-syncrepl a few times now.
>  However, various problems have kept me from doing this permanently, and I've
> had to move back to slurpd.  Every time I then want to try delta-syncrepl again,
> I have to reload the replicas to have their CSN's be in sync with what the
> master has.
>   

slurpd replicates all the operational attributes, including entryCSN. As 
such, reloading the database isn't necessary.
> It has made me think it would be really handy if there was a way to have the
> replica keep its contextCSN updated even if someone isn't using syncrepl, to
> make that conversion easier at a later date.
>   

Just install the syncprov overlay on each replica, and configure the 
syncprov-checkpoint.
> In fact, is there any reason not to simply always keep the CSN information up to
> date?
>   

Yes - all of the syncrepl related reorganization that occurred between 
2.2 to 2.3 was done to insure that the baseline code doesn't have any 
extraneous features. Since writing the contextCSN further serializes all 
write operations, doing so decreases overall write throughput. The 
contextCSN is only useful for syncrepl; nobody who isn't using it should 
have to pay the performance penalty for it.

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