On Mon, Nov 12, 2007 at 10:54:34PM -0500, Tom Lane wrote:
> class. But if that's your problem, "pin these tables in memory" is
> still an awfully crude solution to the problem. I'd be inclined to
> think instead about a scheme that lets references made by
> higher-priority queries bump buffers' use-counts by more than 1,
> or some other way of making the priority considerations visible to an
> automatic cache management algorithm.
While this is true, nobody seems to have those other ways available today.
If there was a quick and easy way to pin certain tables in memory, I think
that administrators might be well-advised to use that mechanism until such
time as the weighted-priority cacheing or whatever shows up. (Of course,
AFAICT, there's no easy way to do the pinning, either, so this all seems a
little academic.)
I have to agree with what Tom says, however, about people thinking they're
smarter than the system. Much of the time, this sort of thumb on the scale
optimisation just moves the cost to some other place, and the admin's
analysis isn't comprehensive enough to turn that up until it's all turned on
in production.
A
--
Andrew Sullivan
Old sigs will return after re-constitution of blue smoke
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
