Question

我希望能够在postgres（9.5）中部分地进行upsert，但是当没有满足所有约束时（例如非null约束），似乎部分upsert失败了

以下是方案和错误的示例

CREATE TABLE jobs (
    id integer PRIMARY KEY,
    employee_name TEXT NOT NULL,
    address TEXT NOT NULL,
    phone_number TEXT
);

CREATE OR REPLACE FUNCTION upsert_job(job JSONB)
RETURNS VOID AS $$
BEGIN
INSERT INTO jobs AS origin VALUES(
    (job->>'id')::INTEGER,
    job->>'employee_name'::TEXT,
    job->>'address'::TEXT,
    job->>'phone_number'::TEXT
) ON CONFLICT (id) DO UPDATE SET
    employee_name = COALESCE(EXCLUDED.employee_name, origin.employee_name),
    address = COALESCE(EXCLUDED.address, origin.address),
    phone_number = COALESCE(EXCLUDED.phone_number, origin.phone_number);
END;
$$ LANGUAGE PLPGSQL SECURITY DEFINER;


--Full insert (OK)
SELECT upsert_job('{"id" : 1, "employee_name" : "AAA", "address" : "City, x street no.y", "phone_number" : "123456789"}'::jsonb);

--Partial update that fulfills constraint (Ok)
SELECT upsert_job('{"id" : 1,  "employee_name" : "BBB", "address" : "City, x street no.y"}'::jsonb);

--Partial update that doesn't fulfill constraint (FAILS)
SELECT upsert_job('{"id" : 1,  "phone_number" : "12345"}'::jsonb);

--ERROR:  null value in column "employee_name" violates not-null constraint
--DETAIL:  Failing row contains (1, null, null, 12345).

如何绕过这个？

Answer 1

以另一种方式来思考，如果id已经存在，该怎么办？您不能只插入电话号码，因为它没有姓名/地址，但这正是您告诉它要做的事情。因此，约束变得疯狂并且失败，因为upsert 尝试插入第一个，然后在插入失败时更新。但是你的插入没有通过约束检查以确定它是否已经存在。

如果你想要部分，你可以做的是告诉它如何处理会违反约束的部分。这样的事情（这不完整，不能处理所有部分数据场景）：

CREATE OR REPLACE FUNCTION upsert_job(job JSONB)
RETURNS VOID AS $$
BEGIN
IF (job->>'phone_number' IS NOT NULL 
    AND job->>'employee_name' IS NOT NULL 
    AND job->>'address' IS NOT NULL) THEN
    INSERT INTO jobs AS origin VALUES(
        (job->>'id')::INTEGER,
        job->>'employee_name'::TEXT,
        job->>'address'::TEXT,
        job->>'phone_number'::TEXT
    ) ON CONFLICT (id) DO UPDATE SET
        employee_name = COALESCE(EXCLUDED.employee_name, origin.employee_name),
        address = COALESCE(EXCLUDED.address, origin.address),
        phone_number = COALESCE(EXCLUDED.phone_number, origin.phone_number);
ELSIF (job->>'phone_number' IS NOT NULL AND (job->>'employee_name' IS NULL AND job->>'address' IS NULL)) THEN
    UPDATE jobs SET phone_number=job->>'phone_number'::TEXT
    WHERE id=(job->>'id')::INTEGER;
END IF;

END;
$$ LANGUAGE PLPGSQL SECURITY DEFINER;

postgres upsert的部分更新违反了约束

1 个答案: