Module capabilities 

Engine capability marker traits.

Each trait in this module marks a capability that some QueryEngine impls satisfy and others don’t. The macro DSL (phase 3+) and the generated input types (phase 2) carry where E: SupportsX bounds on the methods that produce capability-dependent SQL. Using such a method against an engine that doesn’t impl the trait fails to compile with a clear diagnostic.

Engine crates (prax-postgres, prax-mysql, …) impl the traits they satisfy on their concrete engine types. Phase 1 only defines the traits; engine impls land in phase 2.

Traits

SupportsArrayOps

Engine supports native array column operators (contains, overlaps, …).

SupportsCaseInsensitiveMode

Engine has native case-insensitive comparison (ILIKE, COLLATE NOCASE, equivalent). Engines without it fall back to LOWER(...) comparisons and do not need to impl this trait.

SupportsCorrelatedSubquery

Engine supports correlated subqueries in WHERE clauses.

SupportsFullTextSearch

Engine supports full-text search predicates.

SupportsGeneratedColumns

Engine supports DDL for GENERATED ALWAYS AS (expr) STORED|VIRTUAL computed columns.

SupportsJsonPath

Engine supports JSON-path filter operators (path_eq, path_gt, etc.).

SupportsNestedWrites

Engine supports Prisma-style nested writes (create / connect / connect_or_create / disconnect / set / update / upsert / delete / delete_many inside data).

SupportsRelationFilter

Engine supports relation filters (some/every/none/is/is_not) that lower to correlated EXISTS / NOT EXISTS subqueries (or the equivalent in non-SQL engines).

SupportsScalarSubqueryInSelect

Engine supports scalar subqueries in the SELECT list.