syncrepl catchup (ITS#2713)

[quanah@stanford.edu]

Full_Name: Quanah Gibson-Mount
Version: OpenLDAP 2.2 HEAD 9/9/03
OS: Solaris 8
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (171.64.19.82)


Hello,

The syncrepl process implemented in 2.2, makes from what I can tell, a bad
assumption.

It assumes the DB on the replica is empty, meaning that it wants to send
everything it has in its DB to the replica.  Since we pre-load the replicas with
a dump of the master's DB, there is no need for this to be done.  What would be
better, is for the master to generate a tag of some sort, marking a starting
point (probably 0?) that gets incremented as it receives updates, from the time
its DB was created.  That way, if I dump the DB after it has gotten some updates
(so its tag is now 500, lets say), and I load that into a new replica, and bring
it up, the master will only catch it up from change #500 onward.  I have a
feeling this has to be significantly faster than sending our entire 450MB DB
across the network to the replica, as well.

--Quanah