Multi-Database

A single server node hosts multiple named databases, each an isolated graph with its own history. The --db flag points at a root directory; each database lives in its own subdirectory underneath it. A database named default always exists; system is reserved.

DDL

CREATE DATABASE sales
CREATE DATABASE IF NOT EXISTS sales
DROP DATABASE sales
DROP DATABASE IF EXISTS sales
SHOW DATABASES

• Database names are case-insensitive, may be backtick-quoted, and are kept filesystem-safe.
• CREATE DATABASE / DROP DATABASE are replicated as Raft control commands, so the set of databases is consistent across the cluster.
• DROP DATABASE is idempotent and refuses to drop default.
• SHOW DATABASES is a local registry read (also surfaced over Bolt for the Neo4j Browser’s database dropdown).

Selecting a database

Per query, choose the target database in any of three ways:

USE sales
MATCH (o:Order) RETURN count(o)

• A leading USE <db> prefix (also USE <db> AS OF '<id>' for time travel).
• The db field in a REST request body or the Bolt RUN/BEGIN metadata.
• Otherwise the default database.

Selection is per-statement and never sticky across pooled Bolt connections.

Isolation

Databases are fully isolated — a write to default is invisible to sales and vice versa; there is no cross-database query or traversal. Each database has its own engram history, its own full-text indexes, and its own snapshots.

This isolation holds across failover: in a multi-node cluster, CREATE DATABASE replicates to all nodes, writes route to the correct isolated graph, and both databases survive a leader kill with post-failover writes still routing correctly (this is covered by the failover test suite).