anchor.diff:  [source,sql]
   ----
   SELECT R.MESSAGE, C.FIRST_NAME, C.LAST_NAME \
  -FROM RATINGS R LEFT JOIN CUSTOMERS C \
  +FROM RATINGS R INNER JOIN CUSTOMERS C \
   ON R.USER_ID = C.ID \
   LIMIT 5;
   ----
  
positive.code: 
  With the stream registered, we can now re-key the topic, using a KSQL `CSAS` and the `PARTITION BY` clause. Note that we're taking the opportunity to re-serialise the data into Avro format. We're also changing the number of partitions from that of the source (4) to match that of the `ratings` topic (1):
  
  [source,sql]
  ----
  ksql> CREATE STREAM CUSTOMERS_SRC_REKEY \
  
negative.code: 
  [source,bash]
  ----
                    ===========================================
                    =        _  __ _____  ____  _             =
                    =       | |/ // ____|/ __ \| |            =
                    =       | ' /| (___ | |  | | |            =
                    =       |  <  \___ \| |  | | |            =
                    =       | . \ ____) | |__| | |____        =
                    =       |_|\_\_____/ \___\_\______|       =
                    =                                         =
                    =  Streaming SQL Engine for Apache Kafka® =
                    ===========================================
  
  Copyright 2017-2018 Confluent Inc.
  
  CLI v5.0.0, Server v5.0.0 located at http://ksql-server:8088
  
  Having trouble? Type 'help' (case-insensitive) for a rundown of how things work!
  
  