Re: Poor performance using CTE

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.

- Heikki