* Robert Haas (robertmhaas@gmail.com) wrote:
> I dunno what a typical checkpoint size is but I don't think you'll be
> exaggerating much if you imagine that everything that could possibly
> be dirty is.
This is not uncommon for us, at least:
checkpoint complete: wrote 425844 buffers (20.3%); 0 transaction log
file(s) added, 0 removed, 249 recycled; write=175.535 s, sync=17.428 s,
total=196.357 s; sync files=1011, longest=2.675 s, average=0.017 s
That's a checkpoint writing out 20% of 16GB, or over 3GB, and that's
just from one of the four postmasters running- we get this kind of
checkpointing happening on all of them. All told, it's easy for us to
want to write over 12GB during a single checkpoint period on this box.
(checkpoint_timeout is 5m, checkpoint_target is 0.9).
Thankfully, the box has 256G of RAM and so the shared buffers only use
up 25% of the RAM in the box. :)
I'm sure others could post larger numbers.
Thanks,
Stephen
