堆栈深度限制 INSERT 触发器

Question

我在 PostgreSQL 上有这个表，我想创建一个触发器，每次我编辑表中的一行 publications 时，last_edit_date 都会更新为 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出现以下错误：

[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()

这到底是什么意思？它与我的触发器或任何其他定义有关吗？

Answer 1

你的触发器是递归的，即触发器函数执行一个UPDATE再次调用触发器函数。

这里的解决方案是使用BEFORE INSERT OR UPDATE触发器，它修改NEW如下：

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