Re: Ordering of arrays

Hi

pá 23. 8. 2019 v 12:48 odesílatel Mike Martin <mike(at)redtux(dot)plus(dot)com> napsal:

> A question about arrays.
> Is iit possible to reverse an array array?
> for example
> regexp_split_to_array(/srv/progs/programs/Aliens/The_Aliens_1_ens_envsc2_envsc2.mp4,'('/|\.)'),
> which splits on either / or . to extract fileparts
>
> It would be useful to be able to have the array returned reversed, so
> rather than having to use cardinality(array)-1 I have a reversed array and
> say arr[1]
> Also it seems impossible to get a reverse slice (returns null array)
>

you can use own simple function

create or replace function array_rvrs(anyarray)
returns anyarray as $$
select array(select unnest from unnest($1) with ordinality order by
ordinality desc)
$$ language sql immutable strict;

postgres=# select array_rvrs(ARRAY[10, 20, 30, 1, 2, 3]);
┌──────────────────┐
│ array_rvrs │
╞══════════════════╡
│ {3,2,1,30,20,10} │
└──────────────────┘
(1 row)
Regards

Pavel

>
> thanks
>