Re: Core team statement on replication in PostgreSQL

Josh Berkus wrote:
> Marko,
> 
> > But Tom's mail gave me impression core wants to wait until we get "perfect"
> > read-only slave implementation so we wait with it until 8.6, which does
> > not seem sensible.  If we can do slightly inefficient (but simple)
> > implementation
> > right now, I see no reason to reject it, we can always improve it later.
> 
> That's incorrect.  We're looking for a workable solution.  If we could 
> get one for 8.4, that would be brilliant but we think it's going to be 
> harder than that.
> 
> Publishing the XIDs back to the master is one possibility.  We also 
> looked at using "spillover segments" for vacuumed rows, but that seemed 
> even less viable.
> 
> I'm also thinking, for *async replication*, that we could simply halt 
> replication on the slave whenever a transaction passes minxid on the 
> master.  However, the main focus will be on synchrounous hot standby.

Another idea I discussed with Tom is having the slave _delay_ applying
WAL files until all slave snapshots are ready.

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