[postgis-devel] GiST Sorting

[Paul Ramsey]

So about this plan, I don't see the ALTER OPERATOR CLASS recipe that can do the thing we want.

https://www.postgresql.org/docs/14/sql-alteropclass.html

What's the magic incantation?

> On Dec 1, 2021, at 8:30 AM, Regina Obe <lr at pcorp.us> wrote:
> 
>> Initially there was a patch in patchset making user specify sorting function
>> during CREATE INDEX ON table USING gist(column) WITH
>> (sortfunction=zcurve). But everyone said that it's unnessecary complication and
>> we just made the function part of the opclass.
>> But sorting build was not meant to be default!
>> 
>> I'm going to work on this in December, so let's figure out what exactly do we
>> want from PostgreSQL 15?
>> 
>> I'm planning to work on:
>> 1. Fix the concurrency problem in IndexOnlyScan that Peter G. pointed out [0]
>> This will further slow down GiST queries a little, sorry.
>> 2. Sorting items within leaf page in tid order, not provided sorting function.
>> 3. Make better splits of leaf pages. Currently we choose how to split leaf pages
>> solely by sorting function. I want to use split function too. This will consume
>> slightly more memory, but will build better index.
>> 
>> Do we need some functionality to easily enable\disable sorting build? I think
>> chances are very high that we can make it better. But it still will be neither
>> perfect, nor better than buffered build.
>> 
>> Thanks!
>> 
>> Best regards, Andrey Borodin.
> [Regina Obe] 
> I don't think I was in this discussion about CREATE INDEX ON table USING gist(column) WITH
>> (sortfunction=zcurve).
> 
> What was the unnecessary complication?  Was it deemed "user-facing" too complicated
> or "under the hood" too complicated.
> 
> For user-facing I don't see it as too complicated.  Granted it is a bit extra.
> But if it is deemed always not the absolute best, I feel a configure option is fine.
> It's only giving users redundant equally good options that I would consider too complicated.
> 
> 
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