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Re: Issues with generate_series using integer boundaries

From: Thom Brown <thom(at)linux(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PGSQL Mailing List <pgsql-general(at)postgresql(dot)org>
Subject: Re: Issues with generate_series using integer boundaries
Date: 2011-02-01 02:17:17
Message-ID: AANLkTikLXHwrY9vx7q0HJNrK9PZR9tNyNRhubOG0Bc8G@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-generalpgsql-hackers
On 1 February 2011 01:05, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Thom Brown <thom(at)linux(dot)com> writes:
>> I've noticed that if I try to use generate_series to include the upper
>> boundary of int4, it never returns:
>
> I'll bet it's testing "currval > bound" without considering the
> possibility that incrementing currval caused an overflow wraparound.
> We fixed a similar problem years ago in plpgsql FOR-loops...

And here's another case:

SELECT x FROM generate_series(2147483643, 2147483644,5) AS a(x);

A step of 1 would work fine, but forcing it to exceed the boundary in
this way means it never returns.

-- 
Thom Brown
Twitter: @darkixion
IRC (freenode): dark_ixion
Registered Linux user: #516935

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