Re: Hot standby, slot ids and stuff

On Thu, 2009-01-08 at 22:31 +0200, Heikki Linnakangas wrote:
> Simon Riggs wrote:
> > If you want to do things a different way you need to say what you want
> > to do and what effects those changes will have.
>
> I want to reduce the coupling between the primary and the master. The
> less they need to communicate, the better. I want to get rid of slotid,
> and as many of the other extra information carried in WAL records that I
> can. I believe that will make the patch both simpler and more robust.
>
> > Are there tradeoffs? If so what are they?
>
> I don't think there's any big difference in user-visible behavior.

I notice that we are no longer able to record the databaseId for a
connection, so query conflict resolution cannot be isolated to
individual databases any longer.

We might sometimes infer a transaction's databaseId from certain WAL
records but that is only going to be possible within each rmgr, which is
fairly strange.

I'll leave all of the databaseId stuff in there in case we think of
anything good.

--
Simon Riggs www.2ndQuadrant.com
PostgreSQL Training, Services and Support