Re: Core team statement on replication in PostgreSQL

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