Re: Greatest Common Divisor

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com>
Cc: Stephen Frost <sfrost(at)snowman(dot)net>, Vik Fearing <vik(dot)fearing(at)2ndquadrant(dot)com>, Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>, Chapman Flack <chap(at)anastigmatix(dot)net>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Greatest Common Divisor
Date: 2020-01-04 17:01:48
Message-ID: 6387.1578157308@sss.pgh.pa.us
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Dean Rasheed <dean(dot)a(dot)rasheed(at)gmail(dot)com> writes:
> OTOH, for numeric inputs, this could easily end up needing many
> thousands of divisions and it's not hard to construct inputs that take
> minutes to compute, although this is admittedly with ridiculously
> large inputs (~10^130000), and AFAICS, the performance is OK with
> "normal" sized inputs. Should we put a limit on the size of the
> inputs?

No, but a CHECK_FOR_INTERRUPTS in the loop would be well-advised,
if there's not one already inside the called functions.

> There are apparently more efficient algorithms, but I think that
> should definitely be kept out of scope for this patch.

+1

regards, tom lane

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