Re: Synchronous replication

Le 27 juil. 2010 à 15:12, Joshua Tolley <eggyknap@gmail.com> a écrit :
> My concern is that in a quorum system, if the quorum number is less than the
> total number of replicas, there's no way to know *which* replicas composed the
> quorum for any given transaction, so we can't know which servers to fail to if
> the master dies. This isn't different from Oracle, where it looks like
> essentially the "quorum" value is always 1. Your scenario shows that all
> replicas are not created equal, and that sometimes we'll be interested in WAL
> getting committed on a specific subset of the available servers. If I had two
> nearby replicas called X and Y, and one at a remote site called Z, for
> instance, I'd set quorum to 2, but really I'd want to say "wait for server X
> and Y before committing, but don't worry about Z".
>
> I have no idea how to set up our GUCs to encode a situation like that :)

You make it so that Z does not take a vote, by setting it async.

Regards,
--
dim