Attaching to external RDBMSs
Kùzu supports directly scanning from a variety of relational databases using the LOAD FROM statement.
Because RDBMSs are a common source of structured data in enterprises, the purpose behind this set of Kùzu
extensions is currently twofold: (1) to allow users to scan data from external RDBMSs without having to copy it
to a graph database; and (2) if data will be copied over from an RDBMS, this feature also simplifies the pipeline
for copying data from an external RDBMS into Kùzu tables.
The currently available relational database extensions, as well as their minimum required versions, are shown below:
| Extension Name | Description | Minimum Version |
|---|---|---|
duckdb | Scan from an attached DuckDB database | 0.10.0 |
postgres | Scan from an attached PostgreSQL database | 14.0 |
sqlite | Scan from an attached SQLite database | 3.3.0 |
Usage
Click through each tab in this section to see the example usage for your extension of choice.
The DuckDB extension can be installed and loaded by running the following commands using the Kùzu CLI or your preferred language client API:
INSTALL duckdb;LOAD EXTENSION duckdb;1. Create a DuckDB database
To illustrate the usage of this extension, we create a sample DuckDB database of university students in Python.
import duckdb
conn = duckdb.connect('university.db')
# Insert data to person tableconn.execute("CREATE TABLE IF NOT EXISTS person (name VARCHAR, age INTEGER);")conn.execute("INSERT INTO person values ('Alice', 30);")conn.execute("INSERT INTO person values ('Bob', 27);")conn.execute("INSERT INTO person values ('Carol', 19);")conn.execute("INSERT INTO person values ('Dan', 25);")2. Attach database
ATTACH [DB_PATH] AS [alias] (dbtype duckdb, skip_unsupported_table = OPTION)DB_PATH: Path to the DuckDB database instance (can be a relative/absolute/https/s3 path)alias: Database alias to use in Kùzu - If not provided, the database name from DuckDB will be used. When attaching multiple databases, it’s recommended to use aliasing.skip_unsupported_table: Whether kuzu should throw an exception or skip when encountering a table with unsupported datatype. Supported options are: TRUE/FALSE. Default is FALSE.
The below example shows how the university.db DuckDB database can be attached to Kùzu using
the alias uw:
ATTACH 'university.db' AS uw (dbtype duckdb);Note: To attach a remote DuckDB database hosted on S3, users may have to configure the following options:
| Option name | Description |
|---|---|
s3_access_key_id | S3 access key id |
s3_secret_access_key | S3 secret access key |
s3_endpoint | S3 endpoint |
s3_url_style | Uses S3 url style (should either be vhost or path) |
s3_region | S3 region |
Or through environment variables:
| Setting | System environment variable |
|---|---|
| S3 key ID | S3_ACCESS_KEY_ID |
| S3 secret key | S3_SECRET_ACCESS_KEY |
| S3 endpoint | S3_ENDPOINT |
| S3 region | S3_REGION |
| S3 url style | S3_URL_STYLE |
SET S3_URL_STYLE='VHOST';ATTACH 's3://duckdb-blobs/databases/stations.duckdb' as station (dbtype duckdb);LOAD FROM station.stations RETURN count(*);Result:
┌──────────────┐│ COUNT_STAR() ││ INT64 │├──────────────┤│ 578 │└──────────────┘3. Scan from DuckDB tables
Finally, we can utilize the LOAD FROM statement to scan the person table. Note that you need to prefix the
external person table with the database alias (in our example uw). See the USE statement which allows you to
skip this prefixing for a specific default database.
LOAD FROM uw.personRETURN *Result:
---------------| name | age |---------------| Alice | 30 |---------------| Bob | 27 |---------------| Carol | 19 |---------------| Dan | 25 |---------------4. USE: Reference database without alias
You can use the USE statement for attached databases to use a default database name for future operations.
This can be used when reading from an attached database to avoid specifying the full database name
as a prefix to the table name.
Consider the same attached database as above:
ATTACH 'university.db' AS uw (dbtype duckdb);Instead of defining the database name for each subsequent clause like this:
LOAD FROM uw.personRETURN *You can do:
USE uw;LOAD FROM personRETURN *5. Copy data from DuckDB tables
One important use case of the external RDBMS extensions is to facilitate seamless data transfer from the external RDBMS to Kùzu.
In this example, we continue using the university.db database created in the last step, but this time,
we copy the data and persist it to Kùzu. This is done with the COPY FROM statement. Here is an example:
We first create a Person table in Kùzu. In this example we will make Person have the same schema as the one defined in the external RDBMS.
CREATE NODE TABLE Person (name STRING, age INT32, PRIMARY KEY(name));When the schemas are the same, we can copy the data from the external DBMS table to the Kùzu table simply as follows.
COPY Person FROM uw.person;If the schemas are not the same, e.g., Person contains only name property while the external uw.person contains
name and age, we can still use COPY FROM but with a subquery as follows:
COPY Person FROM (LOAD FROM uw.person RETURN name);6. Query the data in Kùzu
Finally, we can verify the data in the Person table in Kùzu.
MATCH (p:Person) RETURN p.*;Result:
------------------| p.name | p.age |------------------| Alice | 30 |------------------| Bob | 27 |------------------| Carol | 19 |------------------| Dan | 25 |------------------7. Clear attached database schema cache
To avoid redundantly retrieving schema information from attached databases, Kùzu maintains a schema cache
including table names and their respective columns and types. Should modifications occur in the schema
via an alternate connection to attached RDBMSs, such as creation or deletion of tables, the cached
schema data may become obsolete. You can use the clear_attached_db_cache() function to refresh cached
schema information in such cases.
CALL clear_attached_db_cache() RETURN *Note: If you have attached to databases from different RDBMSs, say Postgres, DuckDB, and Sqlite, this call will clear the cache for all of them.
8. Detach database
To detach a database, use DETACH [ALIAS] as follows:
DETACH uwThe PostgreSQL extension can be installed and loaded by running the following commands using the Kùzu CLI or your preferred language client API:
INSTALL postgres;LOAD EXTENSION postgres;Set up a PostgreSQL server via Docker
During local development, it’s convenient to set up a PostgreSQL server using Docker. Run the following command to start a PostgreSQL server locally:
docker run --name kuzu-postgres -e POSTGRES_PASSWORD=testpassword -p 5432:5432 --rm postgres:latestNote that the storage volume for this database is not persistent and will be deleted once the container is stopped. Moreover, the password in this case is provided via plain text, which is not recommended in a real use case, so the below example is for testing purposes only.
1. Create a sample PostgreSQL database
To illustrate the usage of the extension, we create a sample Postgres database of university
students. We will use asyncpg,
an asynchronous PostgreSQL client library for Python, to create the database and insert some sample data
via a Python script.
This step assumes you have run pip install asyncpg to install the library, and are using Python 3.10+.
import asyncioimport asyncpg
async def main(): conn = await asyncpg.connect('postgresql://postgres:testpassword@localhost:5432/postgres') # Create and insert data to a new table try: await conn.execute("CREATE TABLE IF NOT EXISTS person (name VARCHAR, age INTEGER);") await conn.execute("INSERT INTO person (name, age) VALUES ('Alice', 30)") await conn.execute("INSERT INTO person (name, age) VALUES ('Bob', 27)") await conn.execute("INSERT INTO person (name, age) VALUES ('Carol', 19)") await conn.execute("INSERT INTO person (name, age) VALUES ('Dan', 25)") except asyncpg.exceptions.DuplicateTableError: print(f"Table already exists, skipping creation and insertion...") # Check results print(await conn.fetch("SELECT * FROM person"))
asyncio.run(main())2. Attach database
ATTACH [PG_CONNECTION_STRING] AS [alias] (dbtype postgres, skip_unsupported_table = OPTION)skip_unsupported_table: Whether kuzu should throw an exception or skip when encountering a table with unsupported datatype. Supported options are: TRUE or FALSE. Default is FALSE.
The below example shows how the university PostgreSQL database can be attached to Kùzu using
the alias uw:
ATTACH 'dbname=university user=postgres host=localhost password=testpassword port=5432' AS uw (dbtype postgres);The ATTACH statement requires the following parameters:
PG_CONNECTION_STRING: PostgreSQL connection string with the necessary parametersalias: Database alias to use in Kùzu - If not provided, the database name from PostgreSQL will be used. When attaching multiple databases, it’s recommended to use aliasing.
The below table lists some common connection string parameters:
| Parameter | Description | Default |
|---|---|---|
dbname | Database name | [user defined] |
host | Host IP address | localhost |
user | Postgres username | postgres |
password | Postgres password | [empty] |
port | Port number | 5432 |
3. Scan from PostgreSQL tables
Finally, we can utilize the LOAD FROM statement to scan the Person table.
LOAD FROM uw.personRETURN *Result:
---------------| name | age |---------------| Alice | 30 |---------------| Bob | 27 |---------------| Carol | 19 |---------------| Dan | 25 |---------------4. USE: Reference database without alias
You can use the USE statement for attached databases to use a default database name for future operations.
This can be used when reading from an attached database to avoid specifying the full database name
as a prefix to the table name.
Consider the same attached database as above:
ATTACH 'university' AS uw (dbtype postgres);Instead of defining the database name for each subsequent clause like this:
LOAD FROM uw.personRETURN *You can do:
USE uw;LOAD FROM personRETURN *5. Copy data from PostgreSQL tables
One important use case of the external RDBMS extensions is to facilitate seamless data transfer from the external RDBMS to Kùzu.
In this example, we continue using the university.db database created in the last step, but this time,
we copy the data and persist it to Kùzu. This is done with the COPY FROM statement. Here is an example:
We first create a Person table in Kùzu. In this example we will make Person have the same schema as the one defined in the external RDBMS.
CREATE NODE TABLE Person (name STRING, age INT32, PRIMARY KEY(name));When the schemas are the same, we can copy the data from the external DBMS table to the Kùzu table simply as follows.
COPY Person FROM uw.person;If the schemas are not the same, e.g., Person contains only name property while the external uw.person contains
name and age, we can still use COPY FROM but with a subquery as follows:
COPY Person FROM (LOAD FROM uw.person RETURN name);6. Query the data in Kùzu
Finally, we can verify the data in the Person table in Kùzu.
MATCH (p:Person) RETURN p.*;Result:
------------------| s.name | s.age |------------------| Alice | 30 |------------------| Bob | 27 |------------------| Carol | 19 |------------------| Dan | 25 |------------------7. Clear attached database schema cache
To avoid redundantly retrieving schema information from attached databases, Kùzu maintains a schema cache
including table names and their respective columns and types. Should modifications occur in the schema
via an alternate connection to attached RDBMSs, such as creation or deletion of tables, the cached
schema data may become obsolete. You can use the clear_attached_db_cache() function to refresh cached
schema information in such cases.
CALL clear_attached_db_cache() RETURN *Note: If you have attached to databases from different RDBMSs, say Postgres, DuckDB, and Sqlite, this call will clear the cache for all of them.
8. Detach database
To detach a database, use DETACH [ALIAS] as follows:
DETACH uwThe SQLite extension can be installed and loaded by running the following commands using the Kùzu CLI or your preferred language client API:
INSTALL sqlite;LOAD EXTENSION sqlite;1. Create a SQLite database
To illustrate the usage of this extension, we create a sample SQLite database of university students in Python.
import sqlite3conn = sqlite3.connect('university.db')cursor = conn.cursor()
cursor.execute("CREATE TABLE IF NOT EXISTS person (name VARCHAR, age INTEGER);")cursor.execute("INSERT INTO person (name, age) VALUES ('Alice', 30);")cursor.execute("INSERT INTO person (name, age) VALUES ('Bob', 27);")cursor.execute("INSERT INTO person (name, age) VALUES ('Carol', 19);")cursor.execute("INSERT INTO person (name, age) VALUES ('Dan', 25);")conn.commit()conn.close()2. Attach database
ATTACH [DB_PATH] AS [alias] (dbtype sqlite, skip_unsupported_table = OPTION)DB_PATH: Path to the SQLite database instance (can be relative or absolute path)alias: Database alias to use in Kùzu - If not provided, the database name from DuckDB will be used. When attaching multiple databases, it’s recommended to use aliasing.skip_unsupported_table: Whether kuzu should throw an exception or skip when encountering a table with unsupported datatype. Supported options:TRUEorFALSE.
The below example shows how the university.db SQLite database can be attached to Kùzu using
the alias uw:
ATTACH 'university.db' AS uw (dbtype sqlite);3. Scan from SQLite tables
Finally, we can utilize the LOAD FROM statement to scan the person table.
LOAD FROM uw.personRETURN *Result:
---------------| name | age |---------------| Alice | 30 |---------------| Bob | 27 |---------------| Carol | 19 |---------------| Dan | 25 |---------------4. USE: Reference database without alias
You can use the USE statement for attached databases to use a default database name for future operations.
This can be used when reading from an attached database to avoid specifying the full database name
as a prefix to the table name.
Consider the same attached database as above:
ATTACH 'university.db' AS uw (dbtype duckdb);Instead of defining the database name for each subsequent clause like this:
LOAD FROM uw.personRETURN *You can do:
USE uw;LOAD FROM personRETURN *5. Copy data from SQLite tables
One important use case of the external RDBMS extensions is to facilitate seamless data transfer from the external RDBMS to Kùzu.
In this example, we continue using the university.db database created in the last step, but this time,
we copy the data and persist it to Kùzu. This is done with the COPY FROM statement. Here is an example:
We first create a Person table in Kùzu. In this example we will make Person have the same schema as the one defined in the external RDBMS.
CREATE NODE TABLE Person (name STRING, age INT32, PRIMARY KEY(name));When the schemas are the same, we can copy the data from the external DBMS table to the Kùzu table simply as follows.
COPY Person FROM uw.person;If the schemas are not the same, e.g., Person contains only name property while the external uw.person contains
name and age, we can still use COPY FROM but with a subquery as follows:
COPY Person FROM (LOAD FROM uw.person RETURN name);6. Query the data in Kùzu
Finally, we can verify the data in the Person table in Kùzu.
MATCH (p:Person) RETURN p.*;Result:
------------------| p.name | p.age |------------------| Alice | 30 |------------------| Bob | 27 |------------------| Carol | 19 |------------------| Dan | 25 |------------------7. Clear attached database schema cache
To avoid redundantly retrieving schema information from attached databases, Kùzu maintains a schema cache
including table names and their respective columns and types. Should modifications occur in the schema
via an alternate connection to attached RDBMSs, such as creation or deletion of tables, the cached
schema data may become obsolete. You can use the clear_attached_db_cache() function to refresh cached
schema information in such cases.
CALL clear_attached_db_cache() RETURN *Note: If you have attached to databases from different RDBMSs, say Postgres, DuckDB, and Sqlite, this call will clear the cache for all of them.
8. Detach database
To detach a database, use DETACH [ALIAS] as follows:
DETACH uw