On 18/02/16 15:38, Dmitry Dolgov wrote:
HiAs far as I see there is one basic update function for jsonb, that can't be covered by `jsonb_set` - insert a new value into an array at arbitrary position. Using `jsonb_set` function we can only append into array at the end/at the beginning, and it looks more like a hack: ``` =# select jsonb_set('{"a": [1, 2, 3]}', '{a, 100}', '4'); jsonb_set --------------------- {"a": [1, 2, 3, 4]} (1 row) =# select jsonb_set('{"a": [1, 2, 3]}', '{a, -100}', '4'); jsonb_set --------------------- {"a": [4, 1, 2, 3]} (1 row) ``` I think the possibility to insert into arbitrary position will be quite useful, something like `json_array_insert` in MySql: ``` mysql> set @j = '["a", {"b": [1, 2]}, [3, 4]]'; mysql> select json_array_insert(@j, '$[1].b[0]', 'x'); json_array_insert(@j, '$[1].b[0]', 'x') +-----------------------------------------+ ["a", {"b": ["x", 1, 2]}, [3, 4]] ``` It can look like `jsonb_insert` function in our case: ``` =# select jsonb_insert('{"a": [0,1,2]}', '{a, 1}', '"new_value"'); jsonb_insert ------------------------------- {"a": [0, "new_value", 1, 2]} (1 row) ```
I think it makes sense to have interface like this, I'd strongly prefer the jsonb_array_insert naming though.
I attached possible implementation, which is basically quite small (all logic-related modifications is only about 4 lines in `setPath` function). This implementation assumes a flag to separate "insert before"/"insert after" operations, and an alias to `jsonb_set` in case if we working with a jsonb object, not an array.
I don't think it's a good idea to use set when this is used on object, I think that we should throw error in that case.
Also this patch needs documentation. -- Petr Jelinek http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
