On 10/23/2014 11:36 AM, David G Johnston wrote:
Andrew Dunstan wrote
On 10/23/2014 09:57 AM, Florian Pflug wrote:
On Oct23, 2014, at 15:39 , Andrew Dunstan <
andrew@
> wrote:
On 10/23/2014 09:27 AM, Merlin Moncure wrote:
On Thu, Oct 23, 2014 at 4:34 AM, Pavel Stehule <
pavel.stehule@
> wrote:
postgres=# select row_to_json(row(10 as A, row(30 as c, 20 AS B) as
x));
row_to_json
------------------------------
{"a":10,"x":{"c":30,"b":20}}
(1 row)
wow -- this is great. I'll take a a look.
Already in 9.4:
andrew=# select
json_build_object('a',10,'x',json_build_object('c',30,'b',20));
json_build_object
----------------------------------------
{"a" : 10, "x" : {"c" : 30, "b" : 20}}
(1 row)
So I'm not sure why we want another mechanism unless it's needed in some
other context.
I've wanted to name the field of rows created with ROW() on more than
one occasion, quite independent from whether the resulting row is
converted
to JSON or not. And quite apart from usefulness, this is a matter of
orthogonality. If we have named fields in anonymous record types, we
should
provide a convenient way of specifying the field names.
So to summarize, I think this is an excellent idea, json_build_object
non-withstanding.
Well, I think we need to see those other use cases. The only use case I
recall seeing involves the already provided case of constructing JSON.
Even if it simply allows CTE and sibqueries to form anonymous record types
which can then be re-expanded in the outer layer for table-like final output
this feature would be useful. When working with wide tables and using
multiple aggregates and joins being able to avoid specifying individual
columns repeatedly is quite desirable.
It would be especially nice to not have to use "as" though, if the source
fields are already so named.
You can already name the output of CTEs and in many cases subqueries,
too. Maybe if you or someone gave a concrete example of something you
can't do that this would enable I'd be more convinced.
cheers
andrew
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
