Re: surprisingly expensive join planning query

Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> writes:
>> (Speaking of which, I don't quite see why this would have been a problem
>> once you got past geqo_threshold; the context resets that GEQO does
>> should've kept things under control.)

> Not sure I follow. geqo_threshold is 12 by default, and the OOM issues
> are hapenning way before that.

Ah, right. But would the peak memory usage keep growing with more than 12
rels?

> It might be that one reason why this example is so bad is that the CTEs
> have *exactly* the different join orders are bound to be costed exactly
> the same I think.

Hmm. I didn't really look into exactly why this example is so awful.

regards, tom lane