PostgreSQL9.62tasks

在PostgreSQL 9.6 中运行2个并行任务的示例代码如下：

-- 创建两个测试表
CREATE TABLE test1 (id integer PRIMARY KEY, name text);
CREATE TABLE test2 (id integer PRIMARY KEY, name text);

-- 第一个并行任务
CREATE FUNCTION task1() RETURNS void AS $$
DECLARE
  i integer;
BEGIN
  FOR i IN 1..1000000 LOOP
    INSERT INTO test1 (id, name) VALUES (i, 'name-' || i);
  END LOOP;
END;
$$
LANGUAGE plpgsql;

-- 第二个并行任务
CREATE FUNCTION task2() RETURNS void AS $$
DECLARE
  i integer;
BEGIN
  FOR i IN 1..1000000 LOOP
    INSERT INTO test2 (id, name) VALUES (i, 'name-' || i);
  END LOOP;
END;
$$
LANGUAGE plpgsql;

-- 并行执行两个任务
SELECT pg_catalog.pg_terminate_backend(pid)
FROM pg_catalog.pg_stat_activity
WHERE pid <> pg_backend_pid() AND pg_last_query_id() LIKE 'concurrent_%';

CREATE TEMP TABLE task_status (name text, status text);

INSERT INTO task_status (name, status) VALUES ('task1', 'running'), ('task2', 'running');

WITH concurrent AS (
  SELECT
    'task1' AS name,
    pg_catalog.pg_background_job_submit('concurrent_task1', $$SELECT task1()$$) AS jobid
  UNION ALL
  SELECT
    'task2' AS name,
    pg_catalog.pg_background_job_submit('concurrent_task2', $$SELECT task2()$$) AS jobid
), status AS (
  SELECT
    cs.name,
    pg_catalog.pg_job_is_complete(c.jobid) AS is_complete
  FROM task_status cs
  JOIN concurrent c ON c.name = cs.name
  WHERE cs.status = 'running'
)
SELECT
  name,
  status,
  CASE WHEN status = true THEN 'done' ELSE 'running' END AS display_status
FROM status;

该示例代码创建了两个测试表(test1和test2)，并使用PL/pgSQL语言创建两个并行任务(task1和task2)。然后，使用pg_background