Re: truncating timestamps on arbitrary intervals
Hi all, it might be a bit late now, but do you know that TimescaleDB already has a similar feature, named time_bucket? https://docs.timescale.com/latest/api#time_bucket Perhaps that can help with some design decisions. I saw your feature on Depesz' "Waiting for PostgreSQL 14" and remembered reading about it just two days ago. Best regards Salek Talangi Am Do., 1. Apr. 2021 um 13:31 Uhr schrieb John Naylor < john.nay...@enterprisedb.com>: > On Sat, Mar 27, 2021 at 1:06 PM Justin Pryzby > wrote: > > > > The current docs seem to be missing a "synopsis", like > > > > + > > +date_trunc(stride, > timestamp, origin) > > + > > The attached > - adds a synopsis > - adds a bit more description to the parameters similar to those in > date_trunc > - documents that negative intervals are treated the same as positive ones > > Note on the last point: This just falls out of the math, so was not > deliberate, but it seems fine to me. We could ban negative intervals, but > that would possibly just inconvenience some people unnecessarily. We could > also treat negative strides differently somehow, but I don't immediately > see a useful and/or intuitive change in behavior to come of that. > > -- > John Naylor > EDB: http://www.enterprisedb.com >
Re: [PATCH] Introduce array_shuffle() and array_sample()
Hi all, reading this blog post https://www.depesz.com/2023/04/18/waiting-for-postgresql-16-add-array_sample-and-array_shuffle-functions/ I became aware of the new feature and had a look at it and the commit https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=888f2ea0a81ff171087bdd1c5c1eeda3b78d73d4 To me the description /* * Shuffle array using Fisher-Yates algorithm. Scan the array and swap * current item (nelm datums starting at ielms) with a randomly chosen * later item (nelm datums starting at jelms) in each iteration. We can * stop once we've done n iterations; then first n items are the result. */ seems wrong. For n = 1 the returned item could never be the 1st item of the array (see "randomly chosen later item"). If this really is the case then the result is not really random. But to me it seems j later can be 0 (making it not really "later"), so this might only be a documentation issue. Best regards Salek Talangi Am Mi., 19. Apr. 2023 um 13:48 Uhr schrieb Daniel Gustafsson < dan...@yesql.se>: > > On 7 Apr 2023, at 17:47, Tom Lane wrote: > > > > Daniel Gustafsson writes: > >> Ah, ok, now I see what you mean, thanks! I'll try to fix up the patch > like > >> this tomorrow. > > > > Since we're running out of time, I took the liberty of fixing and > > pushing this. > > Great, thanks! > > -- > Daniel Gustafsson
