Re: json api WIP patch

On 01/04/2013 03:23 PM, Andrew Dunstan wrote:
>
> On 01/02/2013 05:51 PM, Andrew Dunstan wrote:
>>
>> On 01/02/2013 04:45 PM, Robert Haas wrote:
>>> On Wed, Dec 26, 2012 at 3:33 PM, Andrew Dunstan 
>>> <andrew@dunslane.net> wrote:
>>>> Here is a patch for the first part of the JSON API that was recently
>>>> discussed. It includes the json  parser hook infrastructure and 
>>>> functions
>>>> for json_get and friends, plus json_keys.
>
>
> Udated patch that contains most of the functionality I'm after. One 
> piece left is populate_recordset (populate a set of records from a 
> single json datum which is an array of objects, in one pass). That 
> requires a bit of thought.
>
> I hope most of the whitespace issues are fixed.
>
>


This updated patch contains all the intended functionality, including 
operators for the json_get_path functions, so you can say things like

     select jsonval->array['f1','0','f2] ...

It also removes any requirement to copy the json value before setting up 
the lexer by removing the lexer's requirement to have a nul terminated 
string. Instead the lexer is told the input length and relies on that. 
For this reason, json_in() now calls cstring_get_text() before rather 
than after calling the validation routine, but that's really not 
something worth bothering about.

A couple of points worth noting: it's a pity that we have to run CREATE 
OR REPLACE FUNCTION in system_views.sql in order to set up default 
values for builtin functions. That feels very kludgy. Also, making 
operators for variadic functions is a bit of a pain. I had to set up 
non-variadic version of the same functions (see json_get_path_op and 
json_get_path_as_text_op) just so I could set up the operators. Neither 
of these are exactly showstopper items, just mild annoyances.

I will continue hunting memory leaks, but when Merlin gets done with 
docco I think we'll be far enough advanced to add this to the commitfest.

cheers

andrew