Re: index prefetching

On 12/21/23 18:14, Robert Haas wrote:
> On Thu, Dec 21, 2023 at 11:08 AM Andres Freund <andres@anarazel.de> wrote:
>> But I'd like you to feel guilty (no, not really) and fix it (yes, really) :)
> 
> Sadly, you're more likely to get the first one than you are to get the
> second one. I can't really see going back to revisit that decision as
> a basis for somebody else's new work -- it'd be better if the person
> doing the new work figured out what makes sense here.
> 

I think it's a great example of "hindsight is 20/20". There were
perfectly valid reasons to have two separate nodes, and it's not like
these reasons somehow disappeared. It still is a perfectly reasonable
decision.

It's just that allowing index-only filters for regular index scans seems
to eliminate pretty much all executor differences between the two nodes.
But that's hard to predict - I certainly would not have even think about
that back when index-only scans were added.


regards

-- 
Tomas Vondra
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