Emil Briggs wrote:
I'm working with an application where the database is entirely resident in RAM (the server is a quad opteron with 16GBytes of memory). It's a web application and handles a high volume of queries. The planner seems to be generating poor plans for some of our queries which I can fix by raising cpu_tuple_cost. I have seen some other comments in the archives saying that this is a bad idea but is that necessarily the case when the database is entirely resident in RAM?Emil
Generally, the key knob to twiddle when everything fits in RAM is random_page_cost. If you truly have everything in RAM you could set it almost to 1. 1 means that it costs exactly the same to go randomly through the data then it does to go sequential. I would guess that even in RAM it is faster to go sequential (since you still have to page and deal with L1/L2/L3 cache, etc). But the default random_page_cost of 4 is probably too high for you. John =:->
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