The sequences do not update automatically on the slave(s) in the version we are running ... we do have a cron job that kicks off every few minutes and updates them based opn the current value of their respective columns, which so far has been all we needed. G -----Original Message----- From: Fred Fung [mailto:fred.fung@versaterm.com] Sent: Fri 5/14/2004 6:11 AM To: pgsql-general@postgresql.org Cc: Subject: Re: dbmirror Thanks for all your comments. Is it really true that the sequences in the tables in the Slaves will not be in sync with those in the Master ? If so then this is a show-stopper factor for us to consider using dbmirror, as we use sequences as a unique key in many of the tables in our application. What is Slony-I ? Is it a commerical software ? Is there a website I can read more about it ? Thanks. Fred ----- Original Message ----- From: "Gregory Wood" <gwood@ewebengine.com> To: "Andrew Sullivan" <ajs@crankycanuck.ca> Cc: <pgsql-general@postgresql.org> Sent: Thursday, May 13, 2004 4:10 PM Subject: Re: dbmirror > Does dbmirror do that? No, it does not. It also doesn't support > promoting a slave database to a master; that has to be done manually, so > I wouldn't consider that too big a problem. > > Worse in my opinion is that sequences don't get updated... so a slave > that tries to do an insert on a replicated table (for example, when it > gets manually promoted to master) will find the sequence not where the > master left it, but where it was loaded. Every sequence has to be > manually updated before the database is usable. > > dbmirror was never intended to be anything but a poor man's > replication... and it worked remarkably well for that purpose. Now it's > time to look forward to Slony-I :) > > Greg > > Andrew Sullivan wrote: > > On Wed, May 12, 2004 at 05:53:05PM -0700, Gregory S. Williamson wrote: > > > >>Fred -- > >> > >>Yes, the slave database(s) can be safely used in a R/O mode, > > > > > > Does it also block write transactions in those slaves? The ability > > for clients to write into the slave replicated tables is a problem, > > because it makes promoting a slave node somewhat risky. > > > > Slony-I has a trick to solve this problem, BTW. > > > > A > > > > ---------------------------(end of broadcast)--------------------------- > TIP 3: if posting/reading through Usenet, please send an appropriate > subscribe-nomail command to majordomo@postgresql.org so that your > message can get through to the mailing list cleanly ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@postgresql.org so that your message can get through to the mailing list cleanly ---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
