Andrew Dunstan: Under the wire

On Wednesday, four days before the start of the final commitfest for release 9.2 of PostgreSQL, Robert Haas published YA patch to include JSON as a core type. Basically, his patch just parses the text to make sure it was valid JSON, and stores it as text. I'd just about given up on getting this into release 9.2, but I thought his patch was just a bit too minimal, so I put on the running shoes to add in some functionality to produce JSON from the database: query_to_json(), array_to_json() and record_to_json(). Yesterday I put out this patch, extending his, right on the deadline for this commitfest and thus for this release. A few simple examples from the regression tests:

SELECT query_to_json('select x as b, x * 2 as c from generate_series(1,3) x',false);
                query_to_json                
---------------------------------------------
 [{"b":1,"c":2},{"b":2,"c":4},{"b":3,"c":6}]
(1 row)

SELECT array_to_json('{{1,5},{99,100}}'::int[]);
  array_to_json   
------------------
 [[1,5],[99,100]]
(1 row)

-- row_to_json
SELECT row_to_json(row(1,'foo'));
     row_to_json     
---------------------
 {"f1":1,"f2":"foo"}
(1 row)

and a slightly less simple example:

SELECT row_to_json(q) 
FROM (SELECT $$a$$ || x AS b, 
         y AS c, 
         ARRAY[ROW(x.*,ARRAY[1,2,3]),
               ROW(y.*,ARRAY[4,5,6])] AS z 
      FROM generate_series(1,2) x, 
           generate_series(4,5) y) q;
                            row_to_json                             
--------------------------------------------------------------------
 {"b":"a1","c":4,"z":[{"f1":1,"f2":[1,2,3]},{"f1":4,"f2":[4,5,6]}]}
 {"b":"a1","c":5,"z":[{"f1":1,"f2":[1,2,3]},{"f1":5,"f2":[4,5,6]}]}
 {"b":"a2","c":4,"z":[{"f1":2,"f2":[1,2,3]},{"f1":4,"f2":[4,5,6]}]}
 {"b":"a2","c":5,"z":[{"f1":2,"f2":[1,2,3]},{"f1":5,"f2":[4,5,6]}]}
(4 rows)

We need to sort out a few encoding issues, but I'm now fairly hopeful that we'll have some very useful and fast JSON functionality in release 9.2.