A SQL-Inspired Query Language Designed for Event Sourcing (2025)

2 days ago

Event sourcing presents challenges for querying event streams, and EventQL addresses these by offering a query language tailored for event-sourced systems.
EventQL treats event metadata as first-class citizens, allowing filtering by type, subject, id, time, and data payloads, with indexing opportunities for performance.
Key features include subject pattern matching for intuitive queries on hierarchical data and a PROJECT INTO clause for explicit output shaping.
The language guides toward indexable queries, such as using composite indexes on type, time, and subject for efficiency.
A production-ready Rust parser for EventQL has been developed, supporting standalone use, type inference, and early error detection.
EventQL combines SQL's expressiveness with event-specific optimizations, making it a powerful tool for event-sourced systems.

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