Re: Proposition for autoname columns

Bruce Momjian <bruce@momjian.us> writes:

> On Mon, Nov  2, 2020 at 05:05:29PM +0200, Eugen Konkov wrote:
>> Hello Pgsql-hackers,
>> 
>> When selecting data from json column it named as '?column?'
>> tucha=# select info->>'suma', docn from document order by id desc limit 5;
>>  ?column? | docn 
>> ----------+------
>>  665.97   | 695
>>  513.51   | 632
>>  665.97   | 4804
>>  492.12   | 4315
>>  332.98   | 1302
>> (5 rows)
>> 
>> It would be useful if the name of column will be autoassigned based on
>> name of json key. Like at next query:
>> 
>> tucha=# select info->>'suma' as suma, docn from document order by id desc limit 5;
>>   suma  | docn 
>> --------+------
>>  665.97 | 695
>>  513.51 | 632
>>  665.97 | 4804
>>  492.12 | 4315
>>  332.98 | 1302
>> (5 rows)
>> 
>> 
>> Would it be useful this auto assigned name for column from json?
>
> I think we could do it, but it would only work if the column was output
> as a single json value, and not a multi-key/value field.  I am afraid if
> we tried to do it, the result would be too inconsistent to be useful.

Could this be done via the support function, so that the top-level
operator/function in each select list item can return a suggested column
name if the relevant arguments are constants?

- ilmari
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