Re: [POC] hash partitioning

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: amul sul <sulamul(at)gmail(dot)com>
Cc: Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com>, Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Thom Brown <thom(at)linux(dot)com>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, Yugo Nagata <nagata(at)sraoss(dot)co(dot)jp>, David Steele <david(at)pgmasters(dot)net>, Greg Stark <stark(at)mit(dot)edu>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [POC] hash partitioning
Date: 2017-10-12 14:05:26
Message-ID: CA+Tgmob3-kMhdt2Xrp4dnvMByWTZMX5Q=hxiNSaGGPm8sidmYQ@mail.gmail.com
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On Thu, Oct 12, 2017 at 9:08 AM, amul sul <sulamul(at)gmail(dot)com> wrote:
> How about combining high 32 bits and the low 32 bits separately as shown below?
>
> static inline uint64
> hash_combine64(uint64 a, uint64 b)
> {
> return (((uint64) hash_combine((uint32) a >> 32, (uint32) b >> 32) << 32)
> | hash_combine((unit32) a, (unit32) b));
> }

I doubt that's the best approach, but I don't have something specific
to recommend.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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