这是这个问题的后续问题，所以我知道我可以使用（阻塞）LOCK，但我想使用谓词锁和可序列化事务隔离。

我想要的是一个序列化失败的通用处理程序，它会重试函数/查询X次。

例如，我有这个：

CREATE SEQUENCE account_id_seq;

CREATE TABLE account
(
  id integer NOT NULL DEFAULT nextval('account_id_seq'),
  title character varying(40) NOT NULL,
  balance integer NOT NULL DEFAULT 0,
  CONSTRAINT account_pkey PRIMARY KEY (id)
);

INSERT INTO account (title) VALUES ('Test Account');

CREATE OR REPLACE FUNCTION mytest() RETURNS integer AS $$
DECLARE
    cc integer;
BEGIN
    cc := balance from account where id=1;

    RAISE NOTICE 'Balance: %', cc;
    perform pg_sleep(3);

    update account set balance = cc+10 where id=1 RETURNING balance INTO cc;

    return cc;
END
$$
LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION myretest() RETURNS integer AS $$
DECLARE
    tries integer := 5;
BEGIN
    WHILE TRUE LOOP
        BEGIN -- nested block for exception
            RETURN mytest();
        EXCEPTION
            WHEN SQLSTATE '40001' THEN
                IF tries > 0 THEN
                    tries := tries - 1;
                    RAISE NOTICE 'Restart! % left', tries;
                ELSE
                    RAISE EXCEPTION 'NO RESTARTS LEFT';
                END IF;
        END;
    END LOOP;
END
$$
LANGUAGE plpgsql;

因此，如果直接并发调用mytest（），我在最后一次提交时会遇到序列化失败：

4SO$ psql -c "select mytest()" & PIDA=$! && psql -c "select mytest()" && wait $PIDA
[1] 4909
NOTICE:  Balance: 0
NOTICE:  Balance: 0
 mytest 
--------
     10
(1 row)

ERROR:  could not serialize access due to concurrent update
CONTEXT:  SQL statement "update account set balance = cc+10 where id=1 RETURNING balance"
PL/pgSQL function mytest() line 10 at SQL statement

如果我调用myretest（）它应该尝试执行mytest（）直到第5次尝试它会引发异常。

所以我这里有两点（也许第2点也使第1点无效）：

>