Peter Geoghegan <pg@heroku.com> writes:
> On Fri, Feb 28, 2014 at 5:01 AM, Andrew Dunstan <andrew@dunslane.net> wrote:
>> But anyway, I think we've seen enough of these to conclude that the casts
>> from hstore to jsonb and back should not be implicit. I am fairly confident
>> that changing that would fix your complaint and the similar one that Peter
>> Geoghegan had.
> Yes, it will, but I think that that will create more problems than it
> will solve (which is not to suggest that an implicit cast is the right
> thing). That will require that any non-trivial usage of jsonb requires
> copious casting, where nested hstore does not. The hstore module
> hardly contains some nice extras that a minority of jsonb users will
> be interested in. It contains among other basic things, operator
> classes required to index jsonb. All of my examples will still not
> work, plus a bunch of cases that currently do work reasonably well.
> There'll just be a different error message.
We should have learned by now that implicit casts are generally pretty
dangerous things. I think putting in implicit casts as a band-aid for
missing functionality is a horrid idea that we'll regret for a long
time to come. I gather from upthread comments that the patch currently
actually creates implicit casts in *both* directions? That's doubly
horrid/dangerous.
The more I read in this thread, the more I think that jsonb simply
isn't ready. We should put it off to 9.5 so that we can have a
complete implementation without so many rough edges. I'm afraid that
if we ship it as-is, backwards compatibility considerations are going
to prevent us from filing down the rough edges in future.
regards, tom lane
