Re: Sync Rep: First Thoughts on Code

Josh Berkus wrote:
> 
> Hmmm.  I thought this was pretty clear.  There's three levels of synch 
> which are useful features:
> 
> 1) "synchronus" standby which is really asynchronous, but only has a gap 
> of < 100ms.
> 
> 2) Synchronous standby which guarentees that all committed transactions 
> are on the failover node and that no data will be lost for failover, but 
> the failover node is still in standby mode.
> 
> 3) Synchronous replication where the standby node has identical 
> transactions to the master node, and is queryable read-only.
> 
> Any of these levels would be useful....

Isn't the "queryable read-only" feature totally orthogonal with
how synchronous the replication is?

For one reporting system I have, where new data is continually
being added every second; I'd love to have a read-only-slave
even if that system has the "100ms" gap you mentioned in #1.

Heck I don't care if the queries it runs even have a 100 *minute*
gap; but I sure would like it to be synchronous in the sense
that all the transactions to survive a failure of the primary.