Re: json api WIP patch

On 02/03/2013 08:20 PM, Robert Haas wrote:
> On Fri, Feb 1, 2013 at 6:03 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Daniel Farina <daniel(at)heroku(dot)com> writes:
>>> On Fri, Feb 1, 2013 at 2:08 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>>> I think it's smarter for us to ship functions, and let users wrap them
>>>> in operators if they so choose. It's not difficult for people who
>>> The problem being: even though pg_operator resolves to functions in
>>> pg_proc, they have distinct identities as far as the planner is
>>> concerned w.r.t selectivity estimation and index selection.
>> Yeah, this is surely not a workable policy unless we first move all
>> those planner smarts to apply to functions not operators. And rewrite
>> all the index AM APIs to use functions not operators, too. Now this is
>> something that's been a wish-list item right along, but actually doing
>> it has always looked like a great deal of work for rather small reward.
> Hmm. Well, if the operators are going to be indexable, then I agree
> that's an issue, but isn't -> just a key-extraction operator? That
> wouldn't be something you could index anyway.
>

Er, what? It gives you the value corresponding to a key (or the numbered
array element).

With the Json operators I provided you're more likely to use ->> in an
index, because it returns de-escaped text rather than json, but I don't
see any reason in principle why -> couldn't be used.

cheers

andrew