The kylin.query.spark-conf.spark.master is a configuration property in Apache Kylin that tells it where to find the Spark master when executing queries. This is especially useful when using an external Spark cluster for processing.

The value of this property should be a URL pointing to your Spark master. For example, if you're running a standalone Spark master on the same machine as Kylin and it's listening on the default port, you might set:

kylin.query.spark-conf.spark.master=spark://localhost:7077  

If you're using a Spark cluster managed by Mesos or YARN, you would use their URL schemes instead. Check Spark's documentation for more details about how to specify the master URL.

Remember to restart Kylin after making changes to the configuration file so that they take effect.