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From: Tom Lane <[email protected]>
To: David G. Johnston <[email protected]>
Cc: Adrien Nayrat <[email protected]>
Cc: [email protected]
Subject: Re: Text operators "~<=~ ~<~ ~>=~ ~>~" not documented
Date: Thu, 08 Feb 2018 10:42:34 -0500
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAKFQuwZiuWg5QEk-tN+=Y8JS1cY-xFxe0xZKbMLBh1TM-fSh7w@mail.gmail.com>
References: <[email protected]>
	<CAKFQuwZiuWg5QEk-tN+=Y8JS1cY-xFxe0xZKbMLBh1TM-fSh7w@mail.gmail.com>

"David G. Johnston" <[email protected]> writes:
> On Thu, Feb 8, 2018 at 6:26 AM, Adrien Nayrat <[email protected]>
> wrote:
>> While reading [1] I notice $subject operators lacks of explanation in
>> documentation.

> I'd be inclined to remove those four operators from the spgist page's table
> and replace them with "LIKE".  Then in the text below the table explain
> that LIKE is implemented using a combination of those four operators.

I believe it's intentional that those operators aren't documented: we
don't want people to get in the habit of using them directly.  (These
days, if you actually need what they do, the approved way to spell it
is like 'x < y COLLATE "C"'.)

So actually, my inclination would be to remove them from the spgist table
and put nothing back.  Implying that spgist text_ops fully supports LIKE
would certainly be wrong/confusing --- we do not claim in the main part
of the docs that btree text_ops supports LIKE, even though it has a
comparable level of support as long as you're using C collation.

Since these operators are user-visible in EXPLAIN output, there might be
merit in mentioning them in passing in the LIKE docs.  But we should not
put them in a table with the LIKE ops themselves, IMO.  That would just
invite confusion about what they do and whether you're supposed to use
them directly.

			regards, tom lane

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