From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu> |
Cc: | pgsql-patches(at)postgresql(dot)org |
Subject: | Re: <> operator |
Date: | 2006-03-03 14:38:04 |
Message-ID: | 276.1141396684@sss.pgh.pa.us |
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Lists: | pgsql-patches |
"Qingqing Zhou" <zhouqq(at)cs(dot)toronto(dot)edu> writes:
> There might be another usage of tid < or >. Consider a heap with one middle
> page is broken, I could save most of my data by doing
> INSERT INTO aa SELECT * FROM a WHERE ctid < '(1000, 1)';
> INSERT INTO aa SELECT * FROM a WHERE ctid > '(1001, 0)';
Well, not really, because the planner won't optimize that, hence will
try to apply the WHERE condition to each row of the table, hence you'll
still bomb on the bad page.
> The above example also proves that <= or >= is not required.
<> is "not required" either since NOT (foo = bar) serves perfectly well.
If we're going to do this I'd vote for putting in all four operators
just to minimize the surprise factor. But I'm not sold that there's
a use case, any more than Neil is.
regards, tom lane
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