The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/16/intarray.html
Description:
Hi,
I recently ran into an unusual issue with the intarray extension where if
you subtract one array from another the result is *also* sorted and
de-duplicated. The documentation does not seem to imply that this should be
the case, stating only that the operator "removes elements of the right
array from the left array" and not that it also de-duplicates and sorts the
result... It seems to only occur when subtracting an array. Is this the
intended behavior?
SELECT '{3,1,1,2,2,2}'::int[] - 1; --> {3,2,2,2} as you would expect
SELECT '{3,1,1,2,2,2}'::int[] - '{1}'::int[]; --> {2,3} instead of
{3,2,2,2}
I have confirmed that I get the same result when using PostgreSQL 9 through
16 on DBFiddle. See here: https://dbfiddle.uk/i-eXKhFR
I am using the official PostgreSQL 16.2 Docker image for Debian (PostgreSQL
16.2 (Debian 16.2-1.pgdg120+2) on x86_64-pc-linux-gnu, compiled by gcc
(Debian 12.2.0-14) 12.2.0, 64-bit).
Cheers
Tom