Re: Simple Join

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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




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