Comet Roadmap

Comet is an open-source project and contributors are welcome to work on any issues at any time, but we find it helpful to have a roadmap for some of the major items that require coordination between contributors.

Major Initiatives

Iceberg Integration

Iceberg integration is still a work-in-progress (#2060), with major improvements expected in the next few releases. Once this integration is complete, we plan on switching from the native_comet scan to the native_iceberg_compat scan (#2189) so that complex types can be supported.

Spark 4.0.0 Support

Comet has experimental support for Spark 4.0.0, but there is more work to do (#1637), such as enabling more Spark SQL tests and fully implementing ANSI support (#313) for all supported expressions.

Removing the native_comet scan implementation

We are working towards deprecating (#2186) and removing (#2177) the native_comet scan implementation, which is the originally scan implementation that uses mutable buffers (which is incompatible with best practices around Arrow FFI) and does not support complex types.

Once we are using the native_iceberg_compat scan (which is based on DataFusion’s DataSourceExec) in the Iceberg integration, we will be able to remove the native_comet scan implementation, and can then improve the efficiency of our use of Arrow FFI (#2171).

Ongoing Improvements

In addition to the major initiatives above, we have the following ongoing areas of work:

  • Adding support for more Spark expressions

  • Moving more expressions to the datafusion-spark crate in the core DataFusion repository

  • Performance tuning

  • Nested type support improvements

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Running Spark SQL Tests