David Lang wrote:
On Fri, 16 Dec 2005, Mark Kirkwood wrote:
Right on. Some of these "coerced" plans may perform much better. If
so, we can look at tweaking your runtime config: e.g.
effective_cache_size
random_page_cost
default_statistics_target
to see if said plans can be chosen "naturally".
Mark, I've seen these config options listed as tweaking targets fairly
frequently, has anyone put any thought or effort into creating a test
program that could analyse the actual system and set the defaults based
on the measured performance?
I am sure this has been discussed before, I found this thread -
http://archives.postgresql.org/pgsql-performance/2004-07/msg00189.php
but I seem to recall others (but offhand can't find any of them).
I think that the real difficultly here is that the construction of the
test program is non trivial - for instance, the best test program for
tuning *my* workload is my application with its collection of data, but
it is probably not a good test program for *anyone else's* workload.
cheers
Mark