Glossary

AttributeValue — patinaDB’s tagged property value type: String, Integer, Float, Boolean, Null, List, Map, the temporal types, and Path.

ANN (approximate nearest neighbor) — a vector search that trades exact recall for sublinear speed. patinaDB’s vector index is ANN via IVF-Flat.

BM25 — the ranking function used by full-text search (k1 = 1.2, b = 0.75).

Bolt — Neo4j’s binary client protocol. patinaDB’s server speaks it over raw TCP and WebSocket, so Neo4j drivers and the Browser connect directly.

Engram — one committed unit of change: a list of deterministic delta operations plus metadata (id, timestamp, message). The basis of history, diffs, time travel, and replication.

Compound index — a multi-field B-tree index accelerating equality-prefix + sort queries. Maintained automatically.

Dataset — the embedded API: a versioned graph at a directory, with open / begin / query / commit and the history operations.

DeltaOp — a single low-level mutation (create/delete vertex, set property, set label, create/delete edge). Engrams are lists of these.

Diff (single) — a git-show-style view of one engram.

Diff (range) — a structural, move-aware comparison between two reconstructed graph states.

Fork — create a new database seeded with another’s state at a chosen engram (FORK DATABASE … [AS OF …] INTO …); the fork gets its own independent history.

Embedding — a fixed-length list of floats representing an item in a vector space, stored as an ordinary list-valued property. Queried by similarity via a vector index.

Full-text index — a user-defined BM25 inverted index over string properties of a label or relationship type.

IVF-Flat — the vector index strategy: k-means centroids partition the space into nlist cells; a query scans only the nprobe nearest cells. The centroids are trained once and replicated, so every cluster node returns identical results.

Learner — a Raft node that replicates and applies the log but does not vote; acts as an asynchronous read replica.

openraft — the Rust Raft implementation the server is built on (0.9).

Pin — mark a engram so squash never coalesces it, keeping the point-in-time it marks reachable. Tags pin automatically.

Property-value index — a label-scoped, order-preserving index over a property, enabling O(limit) sorted pagination and efficient equality/range scans.

Quorum — the majority of voters required for Raft to commit. A 1-node cluster has a quorum of 1 (no redundancy); a 3-node cluster tolerates 1 failure.

Reconstruct — rebuild a past graph state from the nearest snapshot plus forward delta replay; the mechanism behind time travel.

Snapshot — a full-graph capture, taken periodically (every 50 commits) to bound reconstruction cost, and shipped in Raft snapshots to bootstrap a node.

Squash — compact a run of old engrams into one synthetic genesis, keeping recent (and pinned) history; the live graph is unchanged, only the log is compacted.

Tag — a named, pinned, snapshotted reference to a engram (like a git tag), so you can time-travel to a meaningful point via AS OF TAG. Replicates across a cluster.

TCK — the openCypher Technology Compatibility Kit, the conformance suite used to measure Cypher coverage (~95% passing).

Time travel — running a read query against the graph as it was at a past engram (--at, USE … AS OF, or the at request field).

Vertex / Edge — a node / a directed, typed relationship in the property graph.

Vector index — a user-defined ANN (IVF-Flat) index over an embedding property, queried with Neo4j syntax (db.index.vector.queryNodes) by cosine or euclidean similarity.

Voter — a Raft node that participates in elections and commit quorums.