FAQ Kylin 4.X

• What is SparderContext? And how should I take care of it ?

                SparderContext is the implemenatation of new distributed query engine which is backend by a spark application. If SparderContext is dead, all your query will failed. So please check its liveness after Kylin instance was started in application list of Resource Manager Web UI.

• Is Hadoop3 supported ?

                Kylin 4.0.0-alpha did not support Hadoop3.

• How to achieve Read/Write Separation Deployment？

                Please refer to Read Write Separation Deployment for Kylin 4.0.

• How to refresh the lookup table snapshot?

                It will be automatically refreshed the next time build.

• How to use the new garbage cleaning tool, which garbage will be cleaned up?

                To be updated

• Can Cube Planner be used?

                Not currently supported.

• Where is the dimension dictionary stored?

                Dimension dictionary is removed.

• What are the optimization methods for build engine?

                To be updated.

• What are the optimization methods for query engine?

                Please refer to Improve query performance by setting shard by column.

• Is Kylin 3.x and Kylin 4.x metadata compatible?

                Fully compatible.

• Is Kylin 3.x and Kylin 4.x cuboid data compatible? If not, will there be a migration plan? 

                The pre-calculated cuboid data is completely incompatible, and there is no migration plan for the time being, due to relatively large effort in development.

• Is the Spark used by Kylin the community version?

                Spark 2.4.6 is currently supported.

• What features will no longer be supported in Kylin 4?

                Please refer to Kylin 4.X Feature List.

• What is the performance of query engine and build engine in Kylin 4?

                To be updated

• Will query results in Kylin 4 be consistent with the previous version? 

                To be updated

• "Caused by: com.amazonaws.services.s3.model.AmazonS3Exception: Please reduce your request rate. (Service: Amazon S3; Status Code: 503; Error Code: SlowDown;"
  • https://aws.amazon.com/premiumsupport/knowledge-center/emr-s3-503-slow-down/
  • We can reverse the Kylin's working dir.
• How to develop UDF and UDAF？

                To be updated

• Does Kylin 4 support AWS Glue?

                To be updated

• Does query on Spark support Spark Schduler Pool setting(resource isolation)?  

                Use different spark pool for different query

• What is the implementation of the new global dictionary?

                Please refer to Global Dictionary on Spark.

• How to store Metadata after not using HBase?

                Kylin supports JDBC to store Metadata, please refer to Use MySQL as Metastore and How to use HBase metastore in Kylin 4.0.