Re: json (b) and null fields

2014-09-29 22:03 GMT+02:00 Andrew Dunstan <andrew(at)dunslane(dot)net>:

>
> On 09/29/2014 03:23 PM, Pavel Stehule wrote:
>
>>
>>
>> 2014-09-27 14:00 GMT+02:00 Stephen Frost <sfrost(at)snowman(dot)net <mailto:
>> sfrost(at)snowman(dot)net>>:
>>
>> Andrew, all,
>>
>> * Andrew Dunstan (andrew(at)dunslane(dot)net
>> <mailto:andrew(at)dunslane(dot)net>) wrote:
>> > I should have been paying a bit more attention to the recent work on
>> > adding an ignore_nulls option to row_to_json(). Here are some
>> > belated thought. I apologize to Pavel and Stephen for not having
>> > commented earlier.
>>
>> No problem at all and thanks for continuing to think about it! We
>> certainly still have quite a bit of time til 9.5 to get this right.
>>
>> > I think this is really a bandaid, and it will fail to catch lots of
>> > cases. Several examples:
>>
>> As discussed on IRC- I agree. I tend to think of JSON objects as
>> relatively simple hstore-like structures and so hadn't considered the
>> complex structure case (as I'm guessing Pavel hadn't either).
>>
>> > I think a much more comprehensive solution would be preferable. What
>> > I have in mind is something like
>> >
>> > json_strip_null_fields(json) -> json
>> >
>> > and a similar function for jsonb.
>>
>> Right, this makes sense to me.
>>
>>
>> It is better than nothing, but it is not nice for JSON due 2x parsing.
>> Probably it is not issue for jsonb.
>>
>> It is not nice, but I have not better .. and it will be faster than any
>> custom solution in plpgsql.
>>
>> Personally, I am not sure, maybe is better to fix row_to_json
>>
>>
>>
> No. There are several reasons for not doing this, starting with the ones
> in my original email on the topic and Tom's objection to the use of
> multiple default options.
>
> This is a non-starter.
>
> JSON parsing is actually pretty darn fast. Every json (as opposed to
> jsonb) function reparses the json. It's true that this is not nearly as
> fast as processing jsonb, but I think for this purpose it's probably not
> too bad.
>
> Frankly, row_to_json is not the most useful case where we could do this
> anyway, so I don't think we should be looking for a heroic effort there. I
> think the consensus for separate functions is the way to go.
>
> I have made a start on coding strip_nulls functions. I'll post a patch
> before too long.
>

ok, I have a different opinion, but it is not strong disagreement

Regards

Pavel

>
> cheers
>
> andrew
>