Re: Hypothetical indexes using BRIN broken since pg10 - Mailing list pgsql-hackers

On 2019-Jun-27, Tom Lane wrote:

> Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> > On 2019-Jun-27, Tom Lane wrote:
> >> FWIW, the proposed patch doesn't seem to me like it adds much more
> >> BRIN-specific knowledge to brincostestimate than is there already.
> 
> > It's this calculation that threw me off:
> >     statsData.revmapNumPages = (indexRanges / REVMAP_PAGE_MAXITEMS) + 1;
> > ISTM that selfuncs has no reason to learn about revmap low-level
> > details.
> 
> Um ... it's accounting for revmap pages already (which is why it needs
> this field set), so hasn't that ship sailed?

Yes, but does it need to know how many items there are in a revmap page?

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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