> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> >> So an inner indexscan for tab1 is definitely a possible plan.
>
> > Yes, that was my point, that a nested loop could easily be involved if
> > the joined table has a restriction. Is there a TODO item here?
>
> More like a "to investigate" --- I'm not sold on the idea that a
> dynamic switch in plan types would be a win. Maybe it would be,
> but...
>
> One thing to think about is that it'd be critically dependent on having
> accurate statistics. Currently, the planner only places bets on the
> average behavior over a whole join. If you make a separate bet on each
> scan, then you open up the risk of betting wrong every time, should
> your stats be out-of-date or otherwise misleading.
I agree. Not sure how to approach this, but I am sure it is dealt with
by most database systems. Can someone find out how other db's handle
this? Is there any research on it?
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
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