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Integrate LangChain with Databricks Unity Catalog tools

Use Databricks Unity Catalog to integrate SQL and Python functions as tools in LangChain and LangGraph workflows. This integration combines the governance of Unity Catalog with LangChain capabilities to build powerful LLM-based applications.

Requirements​

  • Install Python 3.10 and above.

Integrate LangChain with Databricks Unity Catalog​

In this example, you create a Unity Catalog tool, test its functionality, and add it to an agent. Run the following code in a Databricks notebook.

Install dependencies​

Install Unity Catalog AI packages with the Databricks optional and install the LangChain integration package.

This example uses LangChain, but a similar approach can be applied to other libraries. See Integrate Unity Catalog tools with third party generative AI frameworks.

Python
# Install the Unity Catalog AI integration package with the Databricks extra
%pip install unitycatalog-langchain[databricks]

# Install Databricks Langchain integration package
%pip install databricks-langchain
dbutils.library.restartPython()

Initialize the Databricks Function Client​

Initialize the Databricks Function Client.

Python
from unitycatalog.ai.core.base import get_uc_function_client

client = get_uc_function_client()

Define the tool's logic​

Create a Unity Catalog function containing the tool's logic.

Python

CATALOG = "my_catalog"
SCHEMA = "my_schema"

def add_numbers(number_1: float, number_2: float) -> float:
  """
  A function that accepts two floating point numbers adds them,
  and returns the resulting sum as a float.

  Args:
    number_1 (float): The first of the two numbers to add.
    number_2 (float): The second of the two numbers to add.

  Returns:
    float: The sum of the two input numbers.
  """
  return number_1 + number_2

function_info = client.create_python_function(
  func=add_numbers,
  catalog=CATALOG,
  schema=SCHEMA,
  replace=True
)

Test the function​

Test your function to check it works as expected:

Python
result = client.execute_function(
  function_name=f"{CATALOG}.{SCHEMA}.add_numbers",
  parameters={"number_1": 36939.0, "number_2": 8922.4}
)

result.value # OUTPUT: '45861.4'

Wrap the function using the UCFunctionToolKit​

Wrap the function using the UCFunctionToolkit to make it accessible to agent authoring libraries. The toolkit ensures consistency across different libraries and adds helpful features like auto-tracing for retrievers.

Python
from databricks_langchain import UCFunctionToolkit

# Create a toolkit with the Unity Catalog function
func_name = f"{CATALOG}.{SCHEMA}.add_numbers"
toolkit = UCFunctionToolkit(function_names=[func_name])

tools = toolkit.tools

Use the tool in an agent​

Add the tool to a LangChain agent using the tools property from UCFunctionToolkit.

This example authors a simple agent using LangChain's AgentExecutor API for simplicity. For production workloads, use the agent authoring workflow seen in ChatAgent examples.

Python
from langchain.agents import AgentExecutor, create_tool_calling_agent
from langchain.prompts import ChatPromptTemplate
from databricks_langchain import (
  ChatDatabricks,
  UCFunctionToolkit,
)
import mlflow

# Initialize the LLM (replace with your LLM of choice, if desired)
LLM_ENDPOINT_NAME = "databricks-meta-llama-3-3-70b-instruct"
llm = ChatDatabricks(endpoint=LLM_ENDPOINT_NAME, temperature=0.1)

# Define the prompt
prompt = ChatPromptTemplate.from_messages(
  [
    (
      "system",
      "You are a helpful assistant. Make sure to use tools for additional functionality.",
    ),
    ("placeholder", "{chat_history}"),
    ("human", "{input}"),
    ("placeholder", "{agent_scratchpad}"),
  ]
)

# Enable automatic tracing
mlflow.langchain.autolog()

# Define the agent, specifying the tools from the toolkit above
agent = create_tool_calling_agent(llm, tools, prompt)

# Create the agent executor
agent_executor = AgentExecutor(agent=agent, tools=tools, verbose=True)
agent_executor.invoke({"input": "What is 36939.0 + 8922.4?"})
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