SQLiin

SQLiin is a fictional query language described as an extension of SQL designed to unify relational queries with streaming data and incremental computation. The name suggests “SQL in,” reflecting the aim to embed streaming semantics inside SQL.

Design goals include expressiveness, safety, portability, and interoperability with existing SQL engines. It emphasizes gradual adoption through optional extensions and aims to automatically maintain incremental results via materialized views and change data capture.

Key features include streaming sources with a STREAM clause and WINDOW definitions, incremental materialized views, declarative change data capture, explicit null-safety, and query planning that can translate to conventional SQL plus streaming operators. It supports time-based and event-based windowing and aims to preserve a familiar SQL feel while adding streaming semantics.

Syntax and semantics: queries resemble standard SQL but allow a STREAM qualifier on the FROM clause and explicit WINDOW parts. Example: SELECT user_id, COUNT(*) AS cnt FROM purchases STREAM last_15_minutes GROUP BY user_id;

Implementation and status: there is no formal standard for SQLiin. It exists mainly as a conceptual design and in several prototypes or research projects. Real-world adoption is limited, with most practitioners either extending existing databases or using separate streaming engines and connectors to achieve similar behavior.

See also: SQL, streaming SQL, materialized views, change data capture.