Question

是否可以在KSQL中连接两个以上的流/表？

示例：

我有三个流：

CREATE STREAM StreamA (id BIGINT, message VARCHAR) WITH 
(KAFKA_TOPIC='TopicA', VALUE_FORMAT='DELIMITED');
CREATE STREAM StreamB (id BIGINT, aid BIGINT, message VARCHAR) WITH . 
(KAFKA_TOPIC='TopicB', VALUE_FORMAT='DELIMITED');
CREATE STREAM StreamC (id BIGINT, bid BIGINT, message VARCHAR) WITH 
(KAFKA_TOPIC='TopicC', VALUE_FORMAT='DELIMITED');

我尝试通过加入这三个流来创建另一个流：

CREATE STREAM ABCStream AS SELECT * FROM StreamA a JOIN 
StreamB b ON b.aid = a.id JOIN StreamC c WITHIN 1 HOURS ON 
c.bid = b.id;

我收到以下异常：

mismatched input 'JOIN' expecting ';'  
Caused by: org.antlr.v4.runtime.InputMismatchException

Answer 1

否，您最多只能在V5.0以下的KSQL中将每个查询连接两个。您需要使用菊花链式查询，如下所示：

中间流：

CREATE STREAM ABStream AS \
   SELECT * \
     FROM StreamA a \
     JOIN StreamB b \
          ON b.aid = a.id;

多联接流

CREATE STREAM ABCStream AS \
   SELECT * \
     FROM ABStream AB \
     JOIN StreamC c \
          WITHIN 1 HOURS \
          ON c.bid = AB.b_id;

KSQL连接两个以上的流

1 个答案: