Re: Improving our clauseless-join heuristics

Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Apr 13, 2012 at 10:32 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> After some reflection I think that the blame should be pinned on
>> have_relevant_joinclause(), which is essentially defined as "is there
>> any join clause that can be evaluated at the join of these two
>> relations?".  I think it would work better to define it as "is there any
>> join clause that both these relations participate in?".

> I think it's getting a little late in the day to be whacking the
> planner around too much, but I have to admit that seems like a pretty
> good and safe change to me, so maybe we should go ahead and do it.
> I'm a bit worried, though, that with all the planner changes this
> release we are going to spend a lot of time tracking down regressions
> either in planning time or in plan quality.

Could be.  I think though that this fits in pretty naturally with the
parameterized-path changes, since both of them are really directed
towards being able to apply inner indexscans in cases where we could
not before.
        regards, tom lane