FAQ Kylin 4.X

• 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.