Select persisted features

When working with persisted features, FeatureQL provides mechanisms to select multiple features at once and temporarily override their definitions for specific queries.

Wildcard selection with SELECT *()

You can use wildcard syntax to select all features meeting given criteria:

Mix persisted features with local feature definitions:

The wildcard syntax accepts any criteria you would use in a SHOW FEATURES query, making it powerful for selecting feature subsets based on namespace, metadata, or dependency relationships.

Example: Select all features dependencies of a given feature.

@fql-playground(select_wildcard_query_dependencies)

Local feature overrides

You can temporarily override any persisted feature definition within a query without modifying the registry. This is useful for:

• Testing alternative feature implementations
• Debugging feature computations
• Scenario analysis with different parameters

Creating overridable features

Overriding with literal values

This example shows overriding FEATURE1 with a literal value (10), which automatically propagates through the dependency chain to compute FEATURE2 and FEATURE3.

Overriding with new definitions

Here, both FEATURE1 gets a literal override and FEATURE2 gets a completely new definition (FEATURE1 * 10 instead of FEATURE1 + 2). The overrides cascade through the dependency graph.

Key behaviors:

• Local scope: Overrides only affect the current query
• Dependency propagation: Changes automatically flow through dependent features
• Registry preservation: Original definitions remain unchanged in the registry
• Type consistency: Overrides must maintain type compatibility with dependent features