On Tue, Feb 10, 2009 at 11:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> For queries that select only a single index entry, there might be some
> speed degradation, but a quick test suggests it's in the
> single-digit-percentage range if everything's cached; and of course if
> you have to go to disk then the extra CPU cycles to push a bitmap around
> are lost in the noise.
>
> In any case, as a wise man once said "I can make this code arbitrarily
> fast, if it doesn't have to give the right answer". Blowing up in easily
> foreseeable circumstances isn't my idea of giving the right answer.
Sure, but dropping index-scan support is not the only way of fixing
that problem. It has a certain elegance to it, but if it produces a
perceptible slowdown, it may not be the best approach.
...Robert