From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Greg Stark <stark(at)mit(dot)edu> |
Cc: | PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, John Klos <john(at)ziaspace(dot)com> |
Subject: | Re: PostgreSQL for VAX on NetBSD/OpenBSD |
Date: | 2015-08-23 17:17:52 |
Message-ID: | 14369.1440350272@sss.pgh.pa.us |
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Thread: | |
Lists: | pgsql-hackers |
I wrote:
> I think we should replace the whole mess with, say, uint32 for float and
> UINT_MAX for infinity. That will be more portable, probably faster, and
> it will work correctly up to substantially *larger* peak distances than
> the existing code.
After studying the logic a bit more, I realized that the "finite"
distances computed by the algorithm can actually never exceed u_size,
which we're already constraining to be less than SHRT_MAX so that the
adjacency arrays can be "short". So I made it use "short" storage for
distances too, with SHRT_MAX as the infinity value. If we ever find a
need to work with graphs exceeding 32K nodes, it will be trivial to
s/short/int/g in this code.
regards, tom lane
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