postgresql 修改属性

时间：2023-12-26 20:23:25

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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

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edited Mar 20 '15 at 10:23

asked Mar 20 '15 at 6:06

Kokizzu

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1 Answer

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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;

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