Subject: Re: Triage for unimplemented geometric operators
To: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers@lists.postgresql.org
References: <3426566.1638832718@sss.pgh.pa.us>
From: Anton Voloshin <a.voloshin@postgrespro.ru>
Message-ID: <56f39d7c-88cb-ff51-e3fc-ebce97703c81@postgrespro.ru>
Date: Tue, 7 Dec 2021 22:54:57 +0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.14.0
MIME-Version: 1.0
In-Reply-To: <3426566.1638832718@sss.pgh.pa.us>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Archived-At: 
 <https://www.postgresql.org/message-id/56f39d7c-88cb-ff51-e3fc-ebce97703c81%40postgrespro.ru>
Precedence: bulk

On 07/12/2021 06:18, Tom Lane wrote:
> So my inclination for HEAD is to implement poly_distance and nuke
> the others.  I'm a bit less sure about the back branches, but maybe
> just de-document all of them there.

I agree, seems to be a reasonable compromise. Removing 20+-years old 
unused and slightly misleading code probably should overweight the 
natural inclination to implement all of the functions promised in the 
catalog. Enhancing software by deleting the code is not an everyday 
chance and IMHO should be taken, even when it requires an extra 
catversion bump.

I am kind of split on whether it is worth it to implement poly_distance 
in back branches. Maybe there is a benefit in implementing: it should 
not cause any reasonable incompatibilities and will introduce somewhat 
better compatibility with v15+. We could even get away with not updating 
v10..12' docs on poly_distance because it's not mentioned anyway.

I agree on de-documenting all of the unimplemented functions in v13 and 
v14. Branches before v13 should not require any changes (including 
documentation) because detailed table on which operators support which 
geometry primitives only came in 13, and I could not find in e.g. 12's 
documentation any references to the cases you listed previously:
 > dist_lb:	<->(line,box)
 > dist_bl:	<->(box,line)
 > close_sl:	lseg ## line
 > close_lb:	line ## box
 > poly_distance:	polygon <-> polygon
 > path_center:	@@ path

-- 
Anton Voloshin
Postgres Professional, The Russian Postgres Company
https://postgrespro.ru