我已经为我的问题准备了一个简单的测试用例-
在游戏中,玩家 ID 和名称存储在表 users
中:
CREATE TABLE users (
uid SERIAL PRIMARY KEY,
name varchar(255) NOT NULL
);
玩家可以在表reviews
中用2列PK互相评价:
CREATE TABLE reviews (
uid integer NOT NULL CHECK (uid <> author) REFERENCES users ON DELETE CASCADE,
author integer NOT NULL REFERENCES users(uid) ON DELETE CASCADE,
review varchar(255),
PRIMARY KEY(uid, author)
);
这里两个表都填充了示例数据:
INSERT INTO users (uid, name) VALUES (1, 'User 1');
INSERT INTO users (uid, name) VALUES (2, 'User 2');
INSERT INTO users (uid, name) VALUES (3, 'User 3');
INSERT INTO users (uid, name) VALUES (4, 'User 4');
INSERT INTO reviews (uid, author, review) VALUES (1, 2, 'User 2 says: 1 is nice');
INSERT INTO reviews (uid, author, review) VALUES (1, 3, 'User 3 says: 1 is nice');
INSERT INTO reviews (uid, author, review) VALUES (1, 4, 'User 4 says: 1 is nice');
INSERT INTO reviews (uid, author, review) VALUES (2, 1, 'User 1 says: 2 is nice');
INSERT INTO reviews (uid, author, review) VALUES (2, 3, 'User 3 says: 2 is nice');
INSERT INTO reviews (uid, author, review) VALUES (2, 4, 'User 4 says: 2 is ugly');
INSERT INTO reviews (uid, author, review) VALUES (3, 1, 'User 1 says: 3 is nice');
INSERT INTO reviews (uid, author, review) VALUES (3, 2, 'User 2 says: 3 is ugly');
INSERT INTO reviews (uid, author, review) VALUES (3, 4, 'User 4 says: 3 is ugly');
INSERT INTO reviews (uid, author, review) VALUES (4, 1, 'User 1 says: 4 is ugly');
INSERT INTO reviews (uid, author, review) VALUES (4, 2, 'User 2 says: 4 is ugly');
INSERT INTO reviews (uid, author, review) VALUES (4, 3, 'User 3 says: 4 is ugly');
当我的移动应用注意到同一玩家正在使用多个用户 ID 时,它会将记录与如下所示的自定义存储函数合并。
在合并(到 out_uid
)时,用户对他自己的评论被删除,任何由此产生的重叠评论也应该被删除。
(对于合并记录的背景:这真的很有必要,因为我运行了另一个有玩家评论的游戏多年,用户一直缠着我-为什么他们的评论和游戏统计数据不同,当他们登录时通过 Facebook、通过 Google+、通过 Apple Game Center...)
因为没有 UPDATE ... ON CONFLICT DO NOTHING
- 我尝试用以下两个来帮助自己 INSERT ... SELECT ... ON CONFLICT DO NOTHING在自定义存储函数中:
CREATE OR REPLACE FUNCTION merge_users(
in_uids integer[],
OUT out_uid integer
) RETURNS integer AS
$func$
BEGIN
SELECT
MIN(uid)
INTO STRICT
out_uid
FROM users
WHERE uid = ANY(in_uids);
-- delete self-reviews
DELETE FROM reviews
WHERE uid = out_uid
AND author = ANY(in_uids);
DELETE FROM reviews
WHERE author = out_uid
AND uid = ANY(in_uids);
-- try to copy as many reviews OF this user as possible
INSERT INTO reviews (
uid,
author,
review
) SELECT
out_uid, -- change to out_uid
author,
review
FROM reviews
WHERE uid <> out_uid
AND uid = ANY(in_uids)
ON CONFLICT DO NOTHING;
DELETE FROM reviews
WHERE uid <> out_uid
AND uid = ANY(in_uids);
-- try to copy as many reviews BY this user as possible
INSERT INTO reviews (
uid,
author,
review
) SELECT
uid,
out_uid, -- change to out_uid
review
FROM reviews
WHERE author <> out_uid
AND author = ANY(in_uids)
ON CONFLICT DO NOTHING;
DELETE FROM reviews
WHERE author <> out_uid
AND author = ANY(in_uids);
DELETE FROM users
WHERE uid <> out_uid
AND uid = ANY(in_uids);
END
$func$ LANGUAGE plpgsql;
不幸的是,有问题 - 请运行 2 个命令来查看它们:
test=> SELECT out_uid FROM merge_users(ARRAY[1,2]);
out_uid
---------
1
(1 row)
test=> SELECT out_uid FROM merge_users(ARRAY[1,2,3,4]);
ERROR: new row for relation "reviews" violates check constraint "reviews_check"
DETAIL: Failing row contains (1, 1, User 4 says: 3 is ugly).
CONTEXT: SQL statement "INSERT INTO reviews (
uid,
author,
review
) SELECT
uid,
out_uid, -- change to out_uid
review
FROM reviews
WHERE author <> out_uid
AND author = ANY(in_uids)
ON CONFLICT DO NOTHING"
PL/pgSQL function merge_users(integer[]) line 38 at SQL statement
所以删除自评好像不行,求助。
我还想知道是否有比我使用INSERT ... SELECT ... ON CONFLICT DO NOTHING
的技巧更好的方法来合并reviews
记录。
为了您的方便,我创建了一个 SQL Fiddle .
我也曾在很有帮助的 pgsql-general 上问过这个问题邮件列表。
最佳答案
我想我会通过以下方式解决这个问题:
- 根据组合的用户 ID 删除任何 self 评价。
- 将其余部分组合在一起。
我认为这是失败的第一部分。试试这个删除
:
DELETE FROM reviews
WHERE uid = ANY(in_uids) AND author = ANY(in_uids);
也就是说,旧的 uids
的任何组合都是一个问题。我不确定 in_uids
是否包含所有 等效的 uid,但我的想法是整个等效类都用于此目的。
关于sql - 合并具有 2 列主键的表中的记录,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43168406/