如何在FlinkSQL中定义会话窗口(Session Window)和配置其属性？

SELECT 
  SESSION_START(event_time, INTERVAL '30' MINUTE) AS session_start,
  SESSION_END(event_time, INTERVAL '30' MINUTE) AS session_end,
  user_id,
  COUNT(*) AS event_count
FROM user_actions
GROUP BY 
  SESSION(event_time, INTERVAL '30' MINUTE),
  user_id;

CREATE TABLE sessionized_events (
  session_start TIMESTAMP(3),
  session_end TIMESTAMP(3),
  user_id STRING,
  event_count INT,
  WATERMARK FOR event_time AS event_time - INTERVAL '5' SECOND
) WITH (...);
INSERT INTO sessionized_events
SELECT 
  SESSION_START(event_time, INTERVAL '30' MINUTE) AS session_start,
  SESSION_END(event_time, INTERVAL '30' MINUTE) AS session_end,
  user_id,
  COUNT(*) AS event_count
FROM user_actions
GROUP BY 
  SESSION(event_time, INTERVAL '30' MINUTE),
  user_id;