On 21.11.2012 01:53, Tom Lane wrote:
I think the more interesting question is what cases wouldn't be covered by such a rule. Typically you need to use OFFSET 0 in situations where the planner has guessed wrong about costs or rowcounts, and I think people are likely using WITH for that as well. Should we be telling people that they ought to insert OFFSET 0 in WITH queries if they want to be sure there's an optimization fence?
Yes, I strongly feel that we should. Writing a query using WITH often makes it more readable. It would be a shame if people have to refrain from using it, because the planner treats it as an optimization fence.
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