InvariantDB · Architecture

01Data storage

Separate graphs. Each graph has its own data, history log and indexes.
Acknowledged writes. A write is acknowledged after it is recorded in the write-ahead log, and it is replayed automatically after a restart.
Reads and writes. Reads do not wait for writes to finish.
Integrity check on open. A graph whose stored files fail their integrity check does not open, and the error is reported.
Two times per version. Each node and edge version records a valid time (when the fact was true) and a recorded time (when it was written). See Bitemporal queries.
Hash-chained history. The history log records each node and relationship write. Each record stores the hash of the previous record, so changing a past record breaks verification from that point on. GET /graphs/{name}/audit/verify re-hashes the log. The log is not signed or anchored outside the server, so verification does not detect a rewrite of the whole log, or removal of the most recent records, by someone with write access to the server.

Cypher. Queries use openCypher. Temporal clauses select a point in valid time or recorded time: AT VALID, AT RECORDED, AS OF, and OVER VALID/RECORDED BETWEEN. An AT VALID prefix backdates a write.
Procedures. Built-in procedures in the db.* and gds.* namespaces cover agent memory, belief revision, provenance, search, graph algorithms, and compliance. CALL db.listProcedures() returns the catalog.
Search. Full-text (BM25) and vector search run over a label and property.
Constraints. CREATE CONSTRAINT … IS UNIQUE and IS NOT NULL declare constraints; CALL db.constraints() lists the constraints of a graph.

HTTP API. POST /graphs/{name}/cypher runs Cypher. Other endpoints cover search, cursors, schema, indexes, backups, and history verification. The specification is at /openapi.yaml.
MCP. Each graph has a Model Context Protocol endpoint at /graphs/{name}/mcp (JSON-RPC 2.0) with 28 tools. See MCP tools.
SDKs. The Python and Node SDKs wrap the HTTP API. See the SDK reference.

API keys. gq_ keys are bearer credentials. The server stores only a SHA-256 hash of each key. A key issued from the dashboard belongs to your tenant and can be limited to specific graphs and given an expiry.
Dashboard sign-in. The dashboard signs you in with your account. That sign-in token is used for the /cloud/me/* endpoints that create graphs and keys.
OAuth sign-in for MCP clients. MCP clients that support OAuth can connect without storing an API key; you approve the connection by pasting an API key on an approval page.
Capability tokens. An admin can issue short-lived, scoped tokens (at most 300 seconds) for a principal on one graph.
Graph ownership. Graphs created from the dashboard belong to your tenant. All hosted tenants share the same database servers.