Re: Ignoring BRIN for HOT udpates seems broken

On 6/1/22 22:38, Robert Haas wrote:
> On Sat, May 28, 2022 at 4:51 PM Tomas Vondra
> <tomas.vondra@enterprisedb.com> wrote:
>> Yeah, I think that might/should work. We could still create the HOT
>> chain, but we'd have to update the BRIN indexes. But that seems like a
>> fairly complicated change to be done this late for PG15.
> 
> Yeah, I think a revert is better for now. But I agree that the basic
> idea seems salvageable. I think that the commit message is correct
> when it states that "When determining whether an index update may be
> skipped by using HOT, we can ignore attributes indexed only by BRIN
> indexes." However, that doesn't mean that we can ignore the need to
> update those indexes. In that regard, the commit message makes it
> sound like all is well, because it states that "the page range summary
> will be updated anyway" which reads to me like the indexes are in fact
> getting updated. Your example, however, seems to show that the indexes
> are not getting updated.
> 

Yeah, agreed :-( I agree we can probably salvage some of the idea, but
it's far too late for major reworks in PG15.

Attached is a patch reverting both commits (5753d4ee32 and fe60b67250).
This changes the IndexAmRoutine struct, so it's an ABI break. That's not
great post-beta :-( In principle we might also leave amhotblocking in
the struct but ignore it in the code (and treat it as false), but that
seems weird and it's going to be a pain when backpatching. Opinions?


regards

-- 
Tomas Vondra
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