Re: Tracking disk writes? (again)

Tom Lane wrote:
> Erik Jones <erik(at)myemma(dot)com> writes:
> > Well, disk reads, cache hits, transactions commited, transactions
> > rolled back, index size and usage, etc. are all able to be tracked vi
> > the pg catalogue tables and views. But, I haven't seen anything that
> > will give me numbers on actual disk writes done by the database.
>
> One of the reasons you don't see that is that a large fraction of the
> writes are triggered in background by the "bgwriter" process, which
> operates at too low a level to participate in the stats collection
> mechanism. I'm not sure what would be involved in refactoring things
> sufficiently to make that workable, but it'd be nontrivial.

You mean that bgwriter cannot send stat messages? Keep in mind that
these are block-level stats, so there's no need to peek at the page
contents ...

--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.