Hey, I'm wondering if this isn't a bug somewhere in the parser. I had to add additional parenthesis around the regexp_split_to_array.
$ with x as (select 'a b c' a) select regexp_split_to_array(a, ' ') from x; regexp_split_to_array ----------------------- {a,b,c} (1 row) $ with x as (select 'a b c' a) select regexp_split_to_array(a, ' ')[1] from x; ERROR: syntax error at or near "[" LINE 3: regexp_split_to_array(a, ' ')[1] ^ $ with x as (select 'a b c' a) select (regexp_split_to_array(a, ' '))[1] from x; regexp_split_to_array ----------------------- a (1 row) regards, Szymon