postgresql 修改属性

up vote2down votefavorite

From this article, I tried to update or delete property of a JSONB column:

CREATE TABLE xxx (id BIGSERIAL, data JSONB);

INSERT INTO xxx(data) VALUES( '{"a":1,"b":2}' );

SELECT * FROM data;

 id |       data      

----+------------------

  1 | {"a": 1, "b": 2}

create the update function:

CREATE FUNCTION jsonb_merge(JSONB, JSONB)

RETURNS JSONB AS $$

WITH json_union AS (

    SELECT * FROM JSONB_EACH($1)

    UNION ALL

    SELECT * FROM JSONB_EACH($2)

) SELECT JSON_OBJECT_AGG(key, value)::JSONB FROM json_union;

$$ LANGUAGE SQL;

testing:

-- replace

UPDATE xxx SET data = jsonb_merge(data,'{"b":3}') WHERE id = 1;

SELECT * FROM xxx;

 id |       data      

----+------------------

  1 | {"a": 1, "b": 3}

 

-- append

UPDATE xxx SET data = jsonb_merge(data,'{"c":4}') WHERE id = 1;

SELECT * FROM xxx;

 id |           data      

----+-------------------------

  1 | {"a": 1, "b": 3, "c": 4}

The question is:

1. is there any drawback of using JSONB_EACH (jsonb_merge) instead of JSONB_EACH_TEXT (from the article) in this case?
2. how to modify the jsonb_merge so if the second parameter property value is null (something like {"b":null}) the value would be erased?

.

-- remove

UPDATE xxx SET data = jsonb_merge(data,'{"b":null}') WHERE id = 1;

SELECT * FROM xxx;

 id |       data      

----+-----------------

  1 | {"a": 1, "c": 4}

postgresql postgresql-9.4

shareimprove this question

edited Mar 20 '15 at 10:23

asked Mar 20 '15 at 6:06       Kokizzu 273312

add a comment

1 Answer

activeoldestvotes

up vote3down voteaccepted

Question 1 There should be no signicant drawbacks. As the value is converted back to jsonb anyhow I would guess it would be more efficient to keep it that way the whole time. Question 2 Just replace your function with the following (only the part WHERE key NOT IN ... added): CREATE FUNCTION jsonb_merge(JSONB, JSONB) RETURNS JSONB AS $$ WITH json_union AS (     SELECT * FROM JSONB_EACH($1)     UNION ALL     SELECT * FROM JSONB_EACH($2) ) SELECT JSON_OBJECT_AGG(key, value)::JSONB      FROM json_union      WHERE key NOT IN (SELECT key FROM json_union WHERE value ='null'); $$ LANGUAGE SQL; shareimprove this answer