Re: Clarify deleting comments and security labels in synopsis

=?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilmari(at)ilmari(dot)org> writes:
> A user on IRC was confused about how to delete a security label using
> the `SECURITY LABLEL ON … IS …` command, and looking at the docs I can
> see why.

> The synopsis just says `IS 'label'`, which implies that it can only be a
> string. It's not until you read the description for `label` that you
> see "or `NULL` to drop the security label." I propose making the
> synopsis say `IS { 'label' | NULL }` to make it clear that it can be
> NULL as well. The same applies to `COMMENT ON … IS …`, which I've also
> changed similarly in the attached.

Agreed; as-is, the syntax summary is not just confusing but outright
wrong.

I think we could go further and split the entry under Parameters
to match:

'text'
The new comment (must be a simple string literal,
not an expression).

NULL
Write NULL to drop the comment.

regards, tom lane