On 12/12/2014 08:20 PM, Tom Lane wrote:
> We can't just add the operator and worry about usability later;
> if we're thinking we might want to introduce such an automatic
> transformation, we have to be sure the new operator is defined in a
> way that allows the transformation to not change any semantics.
> What that means in this case is that if (jsonb ->> 'foo')::numeric
> would have succeeded, (jsonb ->># 'foo') has to succeed; which means
> it'd better be willing to attempt conversion of string values to
> numeric, not just throw an error on sight.
>
>
Well, I'm not 100% convinced about the magic transformation being a good
thing.
Json numbers are distinct from strings, and part of the justification
for this is to extract a numeric datum from jsonb exactly as stored, on
performance grounds. So turning round now and making that turn a string
into a number if possible seems to me to be going in the wrong direction.
cheers
andrew