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Thread: question about array indexing

question about array indexing

From
Szymon Lipiński
Date:
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

Re: question about array indexing

From
Merlin Moncure
Date:
On Mon, Nov 4, 2019 at 10:05 AM Szymon Lipiński <mabewlun@gmail.com> wrote:
>
> 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)

It's always been that way.  You also have to wrap function column expansions:
select (func()).*

I don't know the exact technical reason why that's required, but my
money is on precedence related problems.

merlin