Horton

Re: [PATCH] Introduce array_shuffle() and array_sample()

Joe Conway <mail@joeconway.com>

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From: Joe Conway <mail@joeconway.com>
To: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>
Cc: Andrew Dunstan <andrew@dunslane.net>, Martin Kalcher <martin.kalcher@aboutsource.net>, John Naylor <john.naylor@enterprisedb.com>, Thomas Munro <thomas.munro@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-07-22T16:49:10Z
Lists: pgsql-hackers, pgsql-general 
On 7/19/22 10:20, Tom Lane wrote:
> Everything else either explicitly rejects more-than-one-D arrays
> or does something that is compatible with thinking of them as
> arrays-of-arrays.

I think I am responsible for at least some of those, and I agree that 
thinking of MD arrays as arrays-of-arrays is preferable even though they 
are not actually that. Long ago[1] Peter E asked me to fix that as I 
recall but it was one of those round tuits that I never found.

> So I withdraw my original position.  These functions should just
> shuffle or select in the array's first dimension, preserving
> subarrays.  Or else be lazy and reject more-than-one-D arrays;
> but it's probably not that hard to handle them.

+1

Joe

[1] 
https://www.postgresql.org/message-id/flat/Pine.LNX.4.44.0306281418020.2178-100000%40peter.localdomain#a064d6dd8593993d799db453a3ee04d1

-- 
Joe Conway
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

Commits

  1. Add array_sample() and array_shuffle() functions.

  2. Use a separate random seed for SQL random()/setseed() functions.