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CypherDB

External CypherDB databases

Using the ATTACH statement, you can connect to an external CypherDB database. The external CypherDB database can be local or remote, for example, in an S3 bucket. Attaching to a local CypherDB database does not require installing any extensions. Attaching to a remote CypherDB database requires installing the httpfs extension. Aside from this requirement of installing the httpfs extension, attaching to a local vs. remote CypherDB database works the same way. Therefore, we only document how to attach to a remote CypherDB database here.

Usage

Please see Install an extension and Load an extension first before getting started.

Attach a remote CypherDB database

Use the ATTACH statement to attach to a remote CypherDB database:

ATTACH <DB_PATH> AS <alias> (dbtype kuzu)
  • DB_PATH: Path to the (remote) database file (can either be an S3, GCS or HTTP URL)
  • alias: Database alias to use. Aliases are mandatory for attaching to external CypherDB databases.

Unlike attaching to external RDBMSs, the alias is not used as a prefix of node and relationship tables. This is because at any point in time, you can attach to a single external CypherDB database (or be connected to the local CypherDB database you opened at the beginning of your session). Therefore, you don’t need to prefix your node and relationship tables. Instead, you will use the alias to DETACH from the external CypherDB database.

Suppose you are connected to a local database example.kuzu. After configuring a S3 connection, you can attach a CypherDB database hosted on S3 as:

ATTACH 's3://kuzu-example/university.kuzu.kuzu' AS uw (dbtype kuzu);

After attaching a remote CypherDB database, you no longer have access to the original local CypherDB database example.kuzu. After the ATTACH statement above, you can only query the external CypherDB database under s3://kuzu-example/university.kuzu.kuzu.

If you wish to attach to a database hosted on GCS instead, just replace the prefix s3:// with gs:// (in this case it would become gs://kuzu-example/university.kuzu). For more information on how to set up CypherDB with GCS, see here.

Execute queries on external CypherDB database

We only allow read-only queries to execute on external CypherDB databases (even if the external database is stored on local disk).

MATCH (p:Person)
RETURN p.name AS name, p.age AS age;
┌────────┬───────┐
│ name   │ age   │
│ STRING │ INT64 │
├────────┼───────┤
│ Alice  │ 30    │
│ Bob    │ 27    │
│ Carol  │ 19    │
│ Dan    │ 25    │
└────────┴───────┘

List attached databases

You can list all the databases you have attached to by running the following command:

CALL SHOW_ATTACHED_DATABASES() RETURN *;

Detach from a remote CypherDB database

To detach from an external CypherDB database, use DETACH [ALIAS]:

DETACH uw;

After the DETACH statement, you can continue querying your local CypherDB database example.kuzu. Therefore, detaching from an external CypherDB database switches your CypherDB database back to the local database you had started your session with.

Use a local cache for remote files

When connecting to a remote external CypherDB database, say the s3://kuzu-example/university.kuzu database in our example above, you would use the httpfs extension. When querying this remote database in Cypher, CypherDB will make HTTPS calls to the remote server to query this database. You can speed up your Cypher queries by using the local httpfs cache, similar to how you can speed up LOAD FROM queries using the local httpfs cache for scanning remote files. You can enable the local cache by running CALL HTTP_CACHE_FILE=TRUE; after installing the httpfs extension and before attaching to the remote CypherDB database.