"Brian Maguire" <bmaguire(at)vantage(dot)com> writes:
> What are the implications to further increasing the checkpoint so say
> 40?
AFAIK the downsides are (a) more disk space eaten for pg_xlog,
(b) if you suffer a crash, it will take longer to recover (because
there'll be more uncheckpointed work to replay); (c) the checkpoint
itself could require more I/O because there's more pending write
activity.
> Also how does 8.0's background-writer feature work and what are going to
> benefits?
The idea of the bgwriter is to trickle out disk writes continuously
instead of having a big write storm at each checkpoint.
regards, tom lane