Horton

Re: Hash Functions

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Andres Freund <andres@anarazel.de>
Cc: Robert Haas <robertmhaas@gmail.com>, Joe Conway <mail@joeconway.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, Yugo Nagata <nagata@sraoss.co.jp>, amul sul <sulamul@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>
Date: 2017-06-02T05:30:19Z
Lists: pgsql-hackers 
On Thu, Jun 1, 2017 at 11:25 AM, Andres Freund <andres@anarazel.de> wrote:
> Secondly, I think that's to a significant degree caused by
> the fact that in practice people way more often partition on types like
> int4/int8/date/timestamp/uuid rather than text - there's rarely good
> reasons to do the latter.

Once we support more pushdowns to partitions, the only question is:
what are your join keys and what are your grouping keys?

Text is absolutely a normal join key or group key. Consider joins on a
user ID or grouping by a model number.

Regards,
     Jeff Davis

Commits

  1. Introduce 64-bit hash functions with a 64-bit seed.

  2. Create a "sort support" interface API for faster sorting.

  3. Add seven kanji characters defined in the Windows 950 codepage to our