Re: SQL/JSON path issues/questions

On Mon, Jun 17, 2019 at 8:40 PM Thom Brown <thom(at)linux(dot)com> wrote:
> On Fri, 14 Jun 2019 at 08:16, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> wrote:
> >
> > Hi, Thom.
> >
> > At Thu, 13 Jun 2019 14:59:51 +0100, Thom Brown <thom(at)linux(dot)com> wrote
> > in <CAA-aLv4VVX=b9RK5hkfPXJczqaiTdqO04teW9i0wiQVhdKcqzw(at)mail(dot)gmail(dot)com>
> > > Hi,
> > >
> > > I've been reading through the documentation regarding jsonpath and
> > > jsonb_path_query etc., and I have found it lacking explanation for
> > > some functionality, and I've also had some confusion when using the
> > > feature.
> > >
> > > ? operator
> > > ==========
> > > The first mention of '?' is in section 9.15, where it says:
> > >
> > > "Suppose you would like to retrieve all heart rate values higher than
> > > 130. You can achieve this using the following expression:
> > > '$.track.segments[*].HR ? (@ > 130)'"
> > >
> > > So what is the ? operator doing here? Sure, there's the regular ?
> >
> > It is described just above as:
> >
> > | Each filter expression must be enclosed in parentheses and
> > | preceded by a question mark.
>
> Can I suggest that, rather than using "question mark", we use the "?"
> symbol, or provide a syntax structure which shows something like:
>
> <path expression> ? <filter expression>
>
> This not only makes this key information clearer and more prominent,
> but it also makes the "?" symbol searchable in a browser for anyone
> wanting to find out what that symbol is doing.

Sounds good for me.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company