Re: (ITS#6710) Mods already refreshed on a forwarding server is lost by its consumer

[rein@OpenLDAP.org]

On 11/15/10 16:39 , rein@OpenLDAP.org wrote:
> New syncprov consumers connecting to a forwarding server and presenting an
> apperently up-to-date cookie will loose any mods that have already taken place
> on the forwarding server if it itself is refreshing from its provider.  This
> should not be a problem if the forwarding server have a sufficiently large
> syncprov log, but a fix for servers without is coming.
The currently committed fix for this its leaves one problem open.  If a 
forwarding server restarts in the middle of the refresh phase, after 
making some changes but before updating the csn, new consumers 
connecting with an apparently up to date csn set after the server comes 
up again will not know that the context is dirty and will loose these 
changes.  The same problem arise if the server restarts between the time 
a locally initiated delete operation is performed in the database and 
the accompanying csn set is saved.

A fix could be to always assume the context is dirty after start up, and 
thereby forcing all clients to undergo the refresh phase even if they 
are in sync until some operation that updates the csn set is performed.  
An unnecessary refresh is probably better than loosing changes..

Rein