On Tue, 16 Feb 2021 at 12:54, Vik Fearing <v...@postgresfriends.org> wrote:
> The SQL standard defines a function called TRIM_ARRAY that surprisingly > has syntax that looks like a function! So I implemented it using a thin > wrapper around our array slice syntax. It is literally just ($1)[1:$2]. > > An interesting case that I decided to handle by explaining it in the > docs is that this won't give you the first n elements if your lower > bound is not 1. My justification for this is 1) non-standard lower > bounds are so rare in the wild that 2) people using them can just not > use this function. The alternative is to go through the unnest dance > (or write it in C) which defeats inlining. > I don't recall ever seeing non-default lower bounds, so I actually think it's OK to just rule out that scenario, but why not something like this: ($1)[:array_lower ($1, 1) + $2 - 1] Note that I've used the 9.6 feature that allows omitting the lower bound.
