On Wed, Apr 8, 2009 at 11:59 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> On Wed, Apr 8, 2009 at 10:33 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> The main point is that the planner will prefer a bitmap scan for any
>>> query that's estimated to return more than quite a small number of rows.
>
>> That makes sense, but what about the nestloop-over-inner-indexscan case?
>
> What about it? The provided patch made no attempt to optimize that
> case.
>
> Doing so might well be interesting, but it's not getting done for 8.4.
> I think it would be quite an invasive patch --- it's hard to see how to
> do it without explicit support at the nestloop join level, so that you
> could pipeline the processing of multiple key values coming from the outer
> side of the join.
OK, I think I'm now understanding your line of thinking. Thanks for
the explanation.
...Robert
