corium-query

The Corium query engine: EDN Datalog, Pull, the entity API, and direct index access — executing on the peer against immutable Db values.

What it does

Everything a peer needs to answer queries locally:

• Datalog — an EDN parser, compiler, planner, and executor for :find / :where queries with rules, aggregates, predicates, and function calls.
• Pull — pull / pull_many for hierarchical entity projection.
• Entity API — the lazy, navigable Entity view over an id.
• Direct index access — datoms-style scans over the covering indexes.
• Query cache (QueryCache) and a planner that uses Db statistics.
• Boundary helpers converting between EDN and Value.

Dependencies

• corium-core — values, keywords, datoms.
• corium-db — the immutable Db values queries run against.
• thiserror for errors; criterion/proptest, corium-log, corium-tx (dev) for benches and conformance/property tests.

Pure, synchronous library code — no async or network dependencies, so the engine is fully testable in the deterministic simulator. Custom function/ predicate resolution is exposed as a seam that corium-cljrs fills with sandboxed cljrs evaluation.

Architecture

All query execution happens on the peer, against an immutable Db value — the engine never talks to the transactor. A query is parsed to an AST, compiled and planned (join order informed by per-attribute statistics), then executed by scanning the covering indexes and threading bindings through frames. Rules, aggregates, and Pull are layered on the same execution core. Because the input is an immutable value, results are stable for the life of that value and can be memoized in the QueryCache. See docs/design/query-engine.md.