C1QL

C1QL is a query language designed for querying JSON-like document stores. It aims to provide a familiar, SQL-inspired syntax while supporting the nested structures common in document databases, such as objects and arrays.

Core design goals emphasize declarative query construction, intuitive projection of fields, and flexible filtering and aggregation. C1QL typically supports navigation of nested data through path expressions, allowing queries to access deep fields without restructuring the data. It is often extended with user-defined functions to enable domain-specific calculations and transformations.

The language generally uses a set of clauses that resemble SQL, including SELECT for projections, FROM to specify the data source, WHERE for filtering, GROUP BY and HAVING for aggregations, ORDER BY for result ordering, and LIMIT to cap result sets. An example query might be: SELECT name, email FROM users WHERE status = 'active' ORDER BY created_at DESC LIMIT 100.

In practice, C1QL is implemented by various JSON-oriented data stores and query engines. Implementations typically rely on indexing strategies to speed up predicate evaluation and path lookups, with support for functional or path-based indexes to optimize nested data access. Performance and feature sets vary between implementations, and there is no universal standard governing C1QL syntax or semantics.

C1QL is one of several JSON-focused query languages used with document databases. It is often discussed in relation to other SQL-like or domain-specific languages for semi-structured data, but it remains a non-standard, implementation-dependent option. Documentation and capabilities are contingent on the specific database or engine being used.

---