Apache Arrow DataFusion vs e6 Query Engine

Apache Arrow DataFusion is a free, extensible query engine written in Rust that uses Apache Arrow as its in-memory format. It is intended for developers building database and analytics systems tailored to particular workloads, rather than as a ready-made hosted database. Queries run in-process, using threads for parallel execution. DataFusion offers SQL and DataFrame APIs, while related subprojects provide Python and Java interfaces. Documented capabilities include SQL parsing and planning, parallel and streaming execution, and query optimization. Built-in data sources include CSV, Parquet, JSON, Avro, and Arrow. Developers can add sources through the TableProvider trait and customize functions, operators, and other components. Runtime features include enforced memory limits and disk spilling for sorts, grouping, and joins. The core project is designed for in-process use; Ballista is a related distributed processing extension. Rust users commonly add DataFusion from crates.io, while official Apache releases are source artifacts. The project recommends verifying release artifacts with an OpenPGP signature or SHA-512 checksum.

e6 Query Engine has no write-up on Specifiction yet; its figures are above.