Databricks-ML-Pro Model Deployment — Timed 10 Questions

Question 1

A machine learning engineer needs to deploy a custom MLflow model that requires a non-standard Python package not available in the default Databricks ML runtime. Which approach ensures the custom dependency is correctly packaged and loaded during model inference?

10 minute time limit — choose an answer to begin.

Accepted Answer

Pass the custom library paths via the extra_pip_requirements parameter when logging the model to ensure dependencies are captured in requirements.txt.. Including extra artifacts like source files and specifying conda or pip requirements within the MLflow pyfunc signature ensures the serving environment installs necessary dependencies. This matters because model serving containers lack arbitrary user libraries unless explicitly declared through MLflow configuration artifacts during the logging phase.

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Manually install the package on the driver node using pip install immediately before calling mlflow.spark.log_model.

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Store the custom python wheel file in DBFS and reference it using a global environment variable inside the serving cluster configuration.

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Modify the cluster spark configuration to append the local package directory to the PYTHONPATH across all worker nodes.

Question 2

An ML engineer needs to schedule daily batch inference for a fraud detection model processing millions of transactions stored in a Delta table. Which deployment pattern provides the most scalable and fault-tolerant architecture within Databricks?

Accepted Answer

Use MLflow pyfunc pandas UDFs loaded via mlflow.pyfunc.spark_udf to score the Delta table distributed across Spark worker nodes.. Using a Databricks Job orchestrated with a Spark-based batch inference notebook leverages distributed computing to process massive datasets efficiently. This pattern is essential because single-node execution would fail on large datasets, whereas distributed Spark processing handles partition-level failures and utilizes cluster resources optimally.

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Write a custom Python script that downloads the entire Delta table into a local pandas DataFrame on the driver node and applies the model.

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Deploy a real-time Model Serving endpoint and send individual HTTP POST requests for every single transaction row using a loop.

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Manually execute an interactive notebook cell each morning and export the scored results to local CSV files.

Question 3

An ML engineer needs to deploy a custom PyTorch model to Databricks Model Serving with a custom preprocessing step that requires external Python packages. Which approach ensures the dependencies and custom logic execute correctly in the serverless inference container?

Accepted Answer

Implement a custom MLflow Pyfunc model wrapper that encapsulates the preprocessing logic and explicitly defines the external conda and pip dependencies in the model flavor configuration.. Deploying models with custom logic requires packaging dependencies using MLflow's model signature and conda environment configurations, or utilizing custom pyfunc implementations with explicit artifact dependencies. This ensures the serverless runtime correctly builds the execution environment and executes the preprocessing transformations without missing library errors during production inference requests.

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Register the PyTorch model without a signature and rely on the serving endpoint to automatically infer input schemas and install required pip packages dynamically at runtime.

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Upload the raw PyTorch state dictionary to DBFS and write a custom scoring script that downloads the weights and initializes the model inside a shared notebook.

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Store the PyTorch weights in Unity Catalog volumes and configure the cluster hosting the model to install the required packages cluster-wide upon every manual restart.

Question 4

A data engineering team is deploying a model using Databricks Model Serving. They need to ensure that the endpoint can handle sudden bursts of traffic while minimizing costs during periods of inactivity. Which configuration strategy for the 'workload_type' and 'scale_to_zero' parameters best achieves this balance?

Accepted Answer

Set the min_provisioned_throughput to 0 and max_provisioned_throughput to a high value.. Databricks Model Serving allows for automatic scaling based on the number of incoming requests. Enabling scale-to-zero allows the infrastructure to shut down completely when no traffic is detected, which is ideal for cost-saving on non-critical or intermittent workloads. Selecting an appropriate workload size ensures that when the model is active, it has sufficient compute resources to handle the expected burst concurrency without failing.

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Configure a Small workload type with a fixed instance count of five to handle bursts.

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Utilize a GPU-based workload type regardless of model size to ensure rapid scaling.

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Disable autoscaling and manually update the endpoint configuration during peak hours.

Question 5

A company is using Databricks Feature Store to serve features for real-time inference. Which TWO components are required to ensure that the model can retrieve the latest feature values with sub-second latency? (Select TWO)

Accepted Answer

An Online Store (e.g., Azure Cosmos DB, AWS DynamoDB) where features are published.. Offline feature stores (Delta tables) are not optimized for the low-latency lookups required by real-time serving endpoints. To support real-time use cases, features must be published to an Online Store (like Cosmos DB or DynamoDB). The model must then be logged with information that allows it to look up these features automatically at inference time.

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A high-concurrency Spark cluster to perform real-time joins on Delta tables.

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A dedicated streaming job that constantly updates the Workspace Model Registry.

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A pre-warmed cache of all possible feature combinations in the Model Serving memory.

Question 6

An organization wants to implement a 'Shadow Deployment' for a new fraud detection model. How is this typically achieved in Databricks Model Serving, and what is its primary benefit?

Accepted Answer

By configuring the endpoint to log all requests, then running the new model offline on those logs.. In a Shadow Deployment, the new model receives the same production traffic as the current 'Champion' model, but its results are not used to make decisions. This allows teams to compare the performance and behavior of the new model against the old one in a real-world setting without risking any negative impact on the business process.

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By routing 100% of traffic to both models and returning the average of their scores.

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By using a 50/50 traffic split and manually discarding half of the results.

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By deploying the model in 'ReadOnly' mode which prevents it from accessing the database.

Question 7

What happens when a model serving endpoint is configured with a 'Small' workload type but the model's Python environment requires 16GB of RAM to load the weights?

Accepted Answer

The endpoint will fail to initialize, and logs will show an OutOfMemory (OOM) error.. If the model's memory requirements exceed the resources allocated to the workload type, the container will fail to start or will crash during the loading phase due to OutOfMemory (OOM) errors. It is essential to match the workload size to the specific resource demands of the model's architecture and its associated libraries.

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The endpoint will automatically upgrade the workload type to 'Medium' to accommodate the model.

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The model will load successfully but will use virtual disk swap, significantly increasing latency.

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The model weights will be partially loaded, resulting in decreased prediction accuracy.

Question 8

A data science team is transitioning from batch prediction to real-time serving using MLflow. They need to ensure that the deployment process is reproducible and allows for easy rollback. Which TWO actions should the team take to meet these requirements?

Accepted Answer

Log the model with all required dependencies and register it in the MLflow Model Registry.. Using MLflow Models and the Model Registry is fundamental for production lifecycle management. By logging the model with its environment dependencies (conda.yaml or requirements.txt), the team ensures the deployment environment matches the training environment. Registering the model version allows for strict version control, which is essential for auditability and implementing seamless rollback strategies when performance degradation is detected after deploying a new model version to production.

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Hardcode the model file path in the production inference script to avoid registry lookups.

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Manually copy the model artifact file to the target production server's local file system.

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Use a local Python script to perform the model inference instead of Databricks Model Serving.

Question 9

A machine learning engineer has registered a model in the Unity Catalog Model Registry and wants to serve it with Databricks Model Serving. The model's requirements.txt includes a private Python package hosted in an internal PyPI repository that requires authentication. Which configuration step is necessary to ensure the serving endpoint can install the package?

Accepted Answer

Specify the private PyPI repository URL and credentials in the serving endpoint's environment configuration using the `pip_repository` field.. The serving endpoint's environment configuration supports a `pip_repository` section where you can specify the URL and credentials for a private PyPI repository. This allows the endpoint build to authenticate and install the required package. Other methods, such as environment variables or custom Docker images, either do not affect pip authentication or add unnecessary complexity.

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Configure the serving endpoint to use a custom Docker image that already has the private package installed.

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Include the package as a wheel file in the model artifacts and reference it with a relative path in requirements.txt.

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Add the private PyPI repository URL and credentials to the environment variables of the serving endpoint.

Question 10

An ML engineer is deploying a model to a Databricks Model Serving endpoint and needs to ensure that only authenticated users with specific permissions can invoke the endpoint. Which mechanism should they use?

Accepted Answer

Configure Unity Catalog privileges on the model and endpoint.. Unity Catalog privileges on the model and endpoint enable fine-grained, identity-based access control, ensuring only authorized users can invoke the endpoint. Other options either do not enforce user-level permissions or rely on insecure practices.

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Enable token-based authentication on the endpoint.

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Use a network security group to restrict IP addresses that can access the endpoint.

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Embed the endpoint URL in a private application and rely on obscurity.