On 5/29/08, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> * The proposed approach is trying to get to "real" replication
> incrementally. Getting rid of the loss window involved in file-by-file
> log shipping is step one, and I suspect that step two is going to be
> fixing performance issues in WAL replay to ensure that slaves can keep
> up. After that we'd start thinking about how to let slaves run
> read-only queries. But even without read-only queries, this will be
> a useful improvement for HA/backup scenarios.
I agree with this plan, but I think this extends also for read-only
queries - we don't need to have the perfect, no-overhead solution
as the first step, instead lets have simple and working solution
with some overhead, then improve that one.
And for the first-step solution, I think letting VACUUM keep tuples
around based on slave queries is preferable to letting slaves lag.
This is useful to more situations.
--
marko
