I'd say that all in all that multi-master is still generally pretty hard to use -- there are packages that do work very well (consider the .org registry, which is slony), but I can't really say with conviction that they are cohesive and easy to use.
You can use synchronous replication in the new version to ensure commits have been flushed to standby before getting a commit ACK. You should run at least two standbys, because otherwise the standby going down halts progress on the primary (after all, it cannot guarantee 2-safety if the one and only secondary is down).
But as for multi-master for scale-out, it's a no-go without some whacking. It may still be worth it, but it's definitely not The Best Thing about Postgres today.
The plain-old replication -- both synchronous and asychronous -- though, works wonderfully. If you just need read scale-out and can tolerate some staleness in results, usually measured in milliseconds (but certain circumstances can make it greater, and these are knowable/measurable in real time) then I think you'd be served pretty well.
You can use synchronous replication in the new version to ensure commits have been flushed to standby before getting a commit ACK. You should run at least two standbys, because otherwise the standby going down halts progress on the primary (after all, it cannot guarantee 2-safety if the one and only secondary is down).
But as for multi-master for scale-out, it's a no-go without some whacking. It may still be worth it, but it's definitely not The Best Thing about Postgres today.
The plain-old replication -- both synchronous and asychronous -- though, works wonderfully. If you just need read scale-out and can tolerate some staleness in results, usually measured in milliseconds (but certain circumstances can make it greater, and these are knowable/measurable in real time) then I think you'd be served pretty well.