Re: CREATE COLLATION - check for duplicate options and error out if found one

On Tue, Apr 27, 2021 at 3:21 PM Bharath Rupireddy
<bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:
>
> Hi,
>
> While reviewing [1], I found that the CREATE COLLATION doesn't throw an error if duplicate options are specified, see [2] for testing a few cases on HEAD. This may end up accepting some of the weird cases, see [2]. It's against other option checking code in the server where the duplicate option is detected and an error thrown if found one. Attached a patch doing that. I chose to have the error message "option \"%s\" specified more than once" and parser_errposition because that's kind of agreed in [3].
>
> Thoughts?
>
> [1] https://www.postgresql.org/message-id/CALj2ACWVd%3D-E6uG5AdHD0MvHY6e4mVzkapT%3DvLDnJJseGjaJLQ%40mail.gmail.com
>
> [2]
> CREATE COLLATION coll_dup_chk (LC_COLLATE = "POSIX", LC_COLLATE = "NONSENSE", LC_CTYPE = "POSIX"); -- ERROR
> CREATE COLLATION coll_dup_chk (LC_COLLATE = "NONSENSE", LC_COLLATE = "POSIX", LC_CTYPE = "POSIX"); -- OK but it's weird
> CREATE COLLATION coll_dup_chk (LC_CTYPE = "POSIX", LC_CTYPE = "NONSENSE", LC_COLLATE = "POSIX"); -- ERROR
> CREATE COLLATION coll_dup_chk (LC_CTYPE = "NONSENSE", LC_CTYPE = "POSIX", LC_COLLATE = "POSIX",); -- OK but it's weird
> CREATE COLLATION coll_dup_chk (PROVIDER = icu, PROVIDER = NONSENSE, LC_COLLATE = "POSIX", LC_CTYPE = "POSIX"); -- ERROR
> CREATE COLLATION coll_dup_chk (PROVIDER = NONSENSE, PROVIDER = icu, LC_COLLATE = "POSIX", LC_CTYPE = "POSIX"); -- OK but it's weird
> CREATE COLLATION case_sensitive (LOCALE = '', LOCALE = "NONSENSE"); -- ERROR
> CREATE COLLATION coll_dup_chk (LOCALE = "NONSENSE", LOCALE = ''); -- OK but it's weird
> CREATE COLLATION coll_dup_chk (DETERMINISTIC = TRUE, DETERMINISTIC = NONSENSE, LOCALE = ''); -- ERROR
> CREATE COLLATION coll_dup_chk (DETERMINISTIC = NONSENSE, DETERMINISTIC = TRUE, LOCALE = ''); -- OK but it's weird
>
> [3] https://www.postgresql.org/message-id/CALj2ACUa%3DZM8QtOLPCHc7%3DWgFrx9P6-AgKQs8cmKLvNCvu7arQ%40mail.gmail.com

+1 for fixing this issue, we have handled this error in other places.
The patch does not apply on head, could you rebase the patch on head
and post a new patch.

Regards,
Vignesh