Question

我在PostgreSQL上有这个表，并且我想触发每次编辑表publications的一行时last_edit_date更新为now()：

CREATE FUNCTION trigger_update_question_timestamp()
  RETURNS "trigger" AS $func$
BEGIN
    UPDATE publications SET last_edit_date = now() WHERE publicationid = NEW.publicationid;
    RETURN NULL;
END;
$func$  LANGUAGE plpgsql;

CREATE TRIGGER answer_update_question_timestamp AFTER INSERT OR UPDATE ON publications
   FOR EACH ROW EXECUTE PROCEDURE trigger_update_question_timestamp();

CREATE TABLE publications
(
    publicationid SERIAL PRIMARY KEY,
    body VARCHAR(1000) NOT NULL ,
    creation_date TIMESTAMP DEFAULT now() NOT NULL,
    userid INTEGER NOT NULL,
    last_edit_date TIMESTAMP,
    CONSTRAINT body_length CHECK (CHAR_LENGTH(body) >= 10 AND CHAR_LENGTH(body) <= 1000),
    CONSTRAINT "FK_publications_users"
        FOREIGN KEY ("userid") REFERENCES users ("userid") ON DELETE SET NULL ON UPDATE CASCADE
);

我正在使用PhpStorm，当我手动编辑一行时，我收到以下错误：

[54001] ERROR: stack depth limit exceeded Hint: Increase the configuration parameter "max_stack_depth" (currently 2048kB), after ensuring the platform's stack depth limit is adequate. Where: SQL statement "SELECT 1 FROM ONLY "public"."users" x WHERE "userid" OPERATOR(pg_catalog.=) $1 FOR KEY SHARE OF x" SQL statement "UPDATE publications SET last_edit_date = now() WHERE publicationid = NEW.publicationid" PL/pgSQL function trigger_update_question_timestamp()

这究竟意味着什么？是否与我的触发器或任何其他定义有关？

Answer 1

您的触发器是递归的，也就是说，触发器函数执行UPDATE再次调用触发器函数。

此处的解决方案是使用BEFORE INSERT OR UPDATE触发器，修改NEW，如下所示：

BEGIN
   NEW.last_edit_date := current_timestamp;
   RETURN NEW;
END;

堆栈深度限制INSERT触发器

1 个答案: