Re: default opclass for jsonb (was Re: Call for GIST/GIN/SP-GIST opclass documentation)

Peter Geoghegan <pg(at)heroku(dot)com> writes:
> On Tue, May 6, 2014 at 3:20 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I wonder whether the most effective use of time at this point
>> wouldn't be to fix jsonb_ops to do that, rather than arguing about
>> what to rename it to. If it didn't have the failure-for-long-strings
>> problem I doubt anybody would be unhappy about making it the default.

> I would expect the selectivity of keys on their own to be very low
> with idiomatic usage of jsonb. Typically, every row in a table will
> have almost the same keys. The current default opclass makes more
> sense for when that isn't the case.

Meh. I would not think that that represents effective use of JSON:
if the rows are all the same, why aren't you exposing that structure
as regular SQL columns? IMHO, the value of JSON fields within a SQL
table is to deal with data that is not so well structured.

In any case, it was certainly the complaint that insertions might
fail altogether that made me (and I assume others) want to not have
jsonb_ops as the default opclass. Is there a good reason not to
fix that limitation while we still can?

regards, tom lane