How to Connect to Lakebase Data in Using Python: 6 Steps

The rich ecosystem of Python modules lets you get to work quicker and integrate your systems more effectively. With the CData Linux/UNIX ODBC Driver for Lakebase and the pyodbc module, you can easily build Lakebase-connected Python applications. This article shows how to use the pyodbc built-in functions to connect to Lakebase data, execute queries, and output the results.

How to Use the CData ODBC Drivers on UNIX/Linux

The CData ODBC Drivers are supported in various Red Hat-based and Debian-based systems, including Ubuntu, Debian, RHEL, CentOS, and Fedora. There are also several libraries and packages that are required, many of which may be installed by default, depending on your system. For more information on the supported versions of Linux operating systems and the required libraries, please refer to the "Getting Started" section in the help documentation (installed and found online).

1. Install the Driver Manager

Before installing the driver, check that your system has a driver manager. For this article, you will use unixODBC, a free and open source ODBC driver manager that is widely supported.

For Debian-based systems like Ubuntu, you can install unixODBC with the APT package manager:

$ sudo apt-get install unixodbc unixodbc-dev

For systems based on Red Hat Linux, you can install unixODBC with yum or dnf:

$ sudo yum install unixODBC unixODBC-devel

The unixODBC driver manager reads information about drivers from an odbcinst.ini file and about data sources from an odbc.ini file. You can determine the location of the configuration files on your system by entering the following command into a terminal:

$ odbcinst -j

The output of the command will display the locations of the configuration files for ODBC data sources and registered ODBC drivers. User data sources can only be accessed by the user account whose home folder the odbc.ini is located in. System data sources can be accessed by all users. Below is an example of the output of this command:

DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/myuser/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

2. Install the Driver

You can download the driver in standard package formats: the Debian .deb package format or the .rpm file format. Once you have downloaded the file, you can install the driver from the terminal.

The driver installer registers the driver with unixODBC and creates a system DSN, which can be used later in any tools or applications that support ODBC connectivity.

For Debian-based systems like Ubuntu, run the following command with sudo or as root:

$ dpkg -i /path/to/package.deb

For Red Hat systems and other systems that support .rpms, run the following command with sudo or as root:

$ rpm -i /path/to/package.rpm

Once the driver is installed, you can list the registered drivers and defined data sources using the unixODBC driver manager:

List the Registered Driver(s)

$ odbcinst -q -d
CData ODBC Driver for Lakebase
...

List the Defined Data Source(s)

$ odbcinst -q -s
CData Lakebase Source
...

To use the CData ODBC Driver for Lakebase with unixODBC, ensure that the driver is configured to use UTF-16. To do so, edit the INI file for the driver (cdata.odbc.lakebase.ini), which can be found in the lib folder in the installation location (typically /opt/cdata/cdata-odbc-driver-for-lakebase), as follows:

cdata.odbc.lakebase.ini

...

[Driver]
DriverManagerEncoding = UTF-16

3. Modify the DSN

The driver installation predefines a system DSN. You can modify the DSN by editing the system data sources file (/etc/odbc.ini) and defining the required connection properties. Additionally, you can create user-specific DSNs that will not require root access to modify in $HOME/.odbc.ini. To connect to Databricks Lakebase, start by setting the following properties:

• DatabricksInstance: The Databricks instance or server hostname, provided in the format instance-abcdef12-3456-7890-abcd-abcdef123456.database.cloud.databricks.com.
• Server: The host name or IP address of the server hosting the Lakebase database.
• Port (optional): The port of the server hosting the Lakebase database, set to 5432 by default.
• Database (optional): The database to connect to after authenticating to the Lakebase Server, set to the authenticating user's default database by default.

OAuth Client Authentication

To authenicate using OAuth client credentials, you need to configure an OAuth client in your service principal. In short, you need to do the following:

1. Create and configure a new service principal
2. Assign permissions to the service principal
3. Create an OAuth secret for the service principal

For more information, refer to the Setting Up OAuthClient Authentication section in the Help documentation.

OAuth PKCE Authentication

To authenticate using the OAuth code type with PKCE (Proof Key for Code Exchange), set the following properties:

• AuthScheme: OAuthPKCE.
• User: The authenticating user's user ID.

For more information, refer to the Help documentation.

/etc/odbc.ini or $HOME/.odbc.ini

[CData Lakebase Source]
Driver = CData ODBC Driver for Lakebase
Description = My Description
DatabricksInstance = lakebase
Server = 127.0.0.1
Port = 5432
Database = my_database
InitiateOAuth = GETANDREFRESH

For specific information on using these configuration files, please refer to the help documentation (installed and found online).

You can follow the procedure below to install pyodbc and start accessing Lakebase through Python objects.

4. Install pyodbc

You can use the pip utility to install the module:

pip install pyodbc

Be sure to import with the module with the following:

import pyodbc

5. Connect to Lakebase Data

You can now connect with an ODBC connection string or a DSN. Below is the syntax for a connection string:

cnxn = pyodbc.connect('DRIVER={CData ODBC Driver for Lakebase};DatabricksInstance=lakebase;Server=127.0.0.1;Port=5432;Database=my_database;InitiateOAuth=GETANDREFRESH;')

Below is the syntax for a DSN:

cnxn = pyodbc.connect('DSN=CData Lakebase Sys;')

6. Execute SQL on Lakebase

Instantiate a Cursor and use the execute method of the Cursor class to execute any SQL statement.

cursor = cnxn.cursor()

Select

You can use fetchall, fetchone, and fetchmany to retrieve Rows returned from SELECT statements:

import pyodbc

cursor = cnxn.cursor()
cnxn = pyodbc.connect('DSN=CData Lakebase Source;User=MyUser;Password=MyPassword')
cursor.execute("SELECT ShipName, ShipCity FROM Orders WHERE ShipCountry = 'USA'")
rows = cursor.fetchall()
for row in rows:
  print(row.ShipName, row.ShipCity)

You can provide parameterized queries in a sequence or in the argument list:

cursor.execute(
  "SELECT ShipName, ShipCity
  FROM Orders
  WHERE ShipCountry = ?", 'USA',1)

Insert

INSERT commands also use the execute method; however, you must subsequently call the commit method after an insert or you will lose your changes:

cursor.execute("INSERT INTO Orders (ShipCountry) VALUES ('USA')")
cnxn.commit()

Update and Delete

As with an insert, you must also call commit after calling execute for an update or delete:

cursor.execute("UPDATE Orders SET ShipCountry = 'USA'")
cnxn.commit()

Metadata Discovery

You can use the getinfo method to retrieve data such as information about the data source and the capabilities of the driver. The getinfo method passes through input to the ODBC SQLGetInfo method.

cnxn.getinfo(pyodbc.SQL_DATA_SOURCE_NAME)

You are now ready to build Python apps in Linux/UNIX environments with connectivity to Lakebase data, using the CData ODBC Driver for Lakebase.