Drill Cassandra Plugin

Drill Cassandra storage plugin allows you to perform SQL queries against Cassandra tables. This storage plugin implementation is based on Apache Calcite adapter for Cassandra.

This storage plugin may be used for querying Scylla DB.

Supported optimizations and features

This storage plugin supports the following optimizations:

• Project pushdown
• Filter pushdown (only expressions supported by Calcite adapter for Cassandra)
• Limit pushdown

Except for these optimizations, Cassandra storage plugin supports the schema provisioning feature. For more details please refer to Specifying the Schema as Table Function Parameter.

Plugin registration

The plugin can be registered in Apache Drill using the drill web interface by navigating to the storage page. Following is the default registration configuration.

{
  "type" : "cassandra",
  "host" : "localhost",
  "port" : 9042,
  "username" : null,
  "password" : null,
  "enabled": false
}

Developer notes

Most of the common classes required for creating storage plugins based on Calcite adapters are placed in the java-exec module, so they can be reused in future plugin implementations.

Here is the list of the classes that may be useful:

• VertexDrelConverterRule with VertexDrel - used to hold plugin-specific part of the plan at the end of the LOGICAL planning phase.
• EnumerableIntermediatePrelConverterRule with EnumerableIntermediatePrel - the same as above, but for the PHYSICAL planning phase.
• EnumerablePrel - responsible for generating java code that will be executed to query the storage plugin data source.
• EnumerableRecordReader - executes java code generated in EnumerablePrel and transforms obtained results to Drill internal representation.