Re: Proposal to introduce a shuffle function to intarray extension
Tom Lane <tgl@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Martin Kalcher <martin.kalcher@aboutsource.net>
Cc: Thomas Munro <thomas.munro@gmail.com>,
PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-07-17T22:46:27Z
Lists: pgsql-hackers, pgsql-general
Martin Kalcher <martin.kalcher@aboutsource.net> writes: > Am 17.07.22 um 08:00 schrieb Thomas Munro: >>> Actually ... is there a reason to bother with an intarray version >>> at all, rather than going straight for an in-core anyarray function? > I played around with the idea of an anyarray shuffle(). The hard part > was to deal with arrays with variable length elements, as they can not > be swapped easily in place. I solved it by creating an intermediate > array of references to the elements. I'll attach a patch with the proof > of concept. This does not look particularly idiomatic, or even type-safe. What you should have done was use deconstruct_array to get an array of Datums and isnull flags, then shuffled those, then used construct_array to build the output. (Or, perhaps, use construct_md_array to replicate the input's precise dimensionality. Not sure if anyone would care.) regards, tom lane
Commits
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Add array_sample() and array_shuffle() functions.
- 888f2ea0a81f 16.0 landed
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Use a separate random seed for SQL random()/setseed() functions.
- 6645ad6bdd81 12.0 cited