From: Tom Lane <tgl@sss.pgh.pa.us>
To: David G. Johnston <david.g.johnston@gmail.com>
Cc: Darryl Dixon <darryl.dixon@gmail.com>
Cc: pgsql-bugs@lists.postgresql.org <pgsql-bugs@lists.postgresql.org>
Subject: Re: BUG #18451: NULL fails to coerce to string when performing string comparison
Date: Tue, 30 Apr 2024 18:30:46 -0400
Message-ID: <1825308.1714516246@sss.pgh.pa.us> (raw)
In-Reply-To: <CAKFQuwZvPW+EH1cDCjti8EC_ke5-84Z6HBPjxfos4q4QUxuv-A@mail.gmail.com>
References: <18451-dc130ad59b7bd7c9@postgresql.org>
<CAKFQuwZ0p7v7QOd_oH37P88dDUAV-wiRanE9K=6qsjG9QN+4tg@mail.gmail.com>
<CAMfewD3G_prBNTfQF183CWA=mObBTzprczVMvMSWk3T0i4++Xg@mail.gmail.com>
<CAKFQuwZvPW+EH1cDCjti8EC_ke5-84Z6HBPjxfos4q4QUxuv-A@mail.gmail.com>
"David G. Johnston" <david.g.johnston@gmail.com> writes:
> Fair, we don’t explicitly document that ‘…’ || NULL yields NULL. It’s more
> of “unless otherwise noted doing stuff with null results in unknown/null
> outcomes”.
Yeah, there's a documentation gap here. I dug around a little and
really couldn't find anything anywhere in our SGML docs that explains
NULL in any detail; we tend to assume that you've already heard of it.
There are a couple of parenthetical remarks in func.sgml that
reference the notion that NULL means "unknown", but you'd never
find those if you were looking for an explanation of what NULL is.
Perhaps that'd be worth a few paras somewhere, though I'm not
very sure where's a good place.
regards, tom lane
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Cc: tgl@sss.pgh.pa.us, david.g.johnston@gmail.com, darryl.dixon@gmail.com, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18451: NULL fails to coerce to string when performing string comparison
In-Reply-To: <1825308.1714516246@sss.pgh.pa.us>
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