RE: pub/sub - specifying optional parameters without values.

On Tuesday, January 31, 2023 10:49 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

Hi,

> Amit Kapila <amit.kapila16@gmail.com> writes:
> > On Tue, Jan 31, 2023 at 4:25 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> Hmph.  I generally think that options defined like this (it's a
> >> boolean, except it isn't) are a bad idea, and would prefer to see
> >> that API rethought while we still can.
>
> > We have discussed this during development and considered using a
> > separate option like parallel = on (or say parallel_workers = n) but
> > there were challenges with the same. See discussion in email [1]. We
> > also checked that we have various other places using something similar
> > for options. For example COPY commands option: HEADER [ boolean |
> > MATCH ].
>
> Yeah, and it's bad experiences with the existing cases that make me not want to
> add more.  Every one of those was somebody taking the easy way out.  It
> generally leads to parsing oddities, such as not accepting all the same spellings
> of "boolean" as before.

I understand the worry of parsing oddities. I think we have tried to make the
streaming option keep accepting all the same spellings of boolean(e.g. the option still
accept(1/0/true/false...)). And this is similar to some other option like COPY
HEADER option which accepts all the boolean value and the 'match' value. Some
other GUCs like wal_compression also behave similarly:
0/1/true/false/on/off/lz1/pglz are all valid values.

Best Regards,
Hou zj