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Re: Creating a VIEW with a POINT column

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jan Urbański <j(dot)urbanski(at)students(dot)mimuw(dot)edu(dot)pl>
Cc: Nick <nboutelier(at)hotmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Creating a VIEW with a POINT column
Date: 2008-06-26 00:01:20
Message-ID: 25421.1214438480@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
=?UTF-8?B?SmFuIFVyYmHFhHNraQ==?= <j(dot)urbanski(at)students(dot)mimuw(dot)edu(dot)pl> writes:
> All three try to sort the table first, and as there's no comparision 
> operator for the POINT datatype, they fail. Which seems to be wrong - if 
> there is no comparision operator, you still can do DISTINCT, only less 
> efficiently.

Type point has no btree opclass, no hash opclass, and not even an
operator named "=" (it looks like the functionality is named ~=
for some odd reason).  I'd be interested to hear either a proposal of
a principled way to define DISTINCT, or a way to implement it that
was better than comparing every element to every other element...

			regards, tom lane

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