Ballista 0.3.0-alpha-2

02 Aug 2020

This is the second 0.3.0 alpha release and improves overall stability and UX.

This release contains the following improvements to the Rust project:

• It is now possible to specify configuration options such as parquet and csv reader batch sizes when submitting queries.
• Executors now use a simpler and more efficient worker thread model.
• The scheduler is slightly more efficient and uses a stateful client when communicating with executors, reducing the overhead of creating new network connections.
• The TPC-H example now accepts command-line arguments.
• The HashAggregateExec operator is re-implemented using async/await, removing the overhead of a dedicated thread.
• Explicit projections are now supported.
• Improvements to Docker packaging.
• Fixed bug where client-supplied schema was ignored.

This release contains the following improvements to the JVM project:

• Serde code added for new protobuf messages involved in distributed query execution.

Known issues:

• The scheduler is still extremely simple and inefficient.
• Distributed query performance is not optimized yet.