Jesper Krogh <jesper@krogh.cc> wrote:
> My thought was that if I tuned autovacuum to be "really
> aggressive" then I could get autovacuum to actually vacuum the
> tuples before they get evicted from the OS cache thus effectively
> "saving" the IO-overhead of vacuuming.
Interesting concept. That might be a way to avoid the extra disk
I/O to set hint bits, and then some. I haven't tried it, but I'm
going to make a note to take a look when (if???) I get some free
time. If you give it a try, please post the results. If you're I/O
bound (rather than CPU bound) and you choose *extremely* aggressive
settings, the multiple writes to pages *might* collapse in cache and
significantly reduce I/O.
I don't think I'd try it on a release prior to 8.4, however. Nor
would I consider trying this in a production environment without a
good set of tests.
-Kevin