ML Data Scientist Databricks-Machine-Learning-Professional Reddit Questions

Real-time deployment is a type of model deployment where predictions are computed on-demand at query time. This can be useful when the feature values are not available until the time of delivery, and results are needed exceedingly fast for one record at a time. Real-time deployment can leverage Databricks Model Serving, which allows users to host MLflow models as REST endpoints on Databricks1. The other options are incorrect because they either do not meet the requirements or are not supported by Databricks Machine Learning. Edge/on-device deployment is a type of model deployment where predictions are computed on the edge device, such as a smartphone or a sensor. This can be useful when there is limited or no network connectivity, or when privacy and security are important. However, edge deployment is not supported by Databricks Machine Learning2. Streaming deployment is a type of model deployment where predictions are computed on streaming data, such as sensor readings or web logs. This can be useful when the data volume is high and the results need to be updated continuously. However, streaming deployment is not supported by Databricks Model Serving1. Batch deployment is a type of model deployment where predictions are computed in advance and stored for later use. This can be useful when the feature values are known ahead of time and the predictions do not need to be delivered quickly. However, batch deployment does not meet the requirements of this scenario, as the feature values are not available until the time of delivery, and results are needed exceedingly fast for one record at a time. References: MLflow Model Serving, Model deployment patterns

 The mlflow.register_model function takes two arguments: model_uri and name. The model_uri is the URI of the model that was logged to MLflow, which can be obtained from the best run object. The name is the name of the registered model in the MLflow Model Registry. Therefore, the correct line of code to register the model is:

mlflow.register_model(model_uri, “best_model”)

This will create a new registered model with the name “best_model” and register the model version from the best run as the first version of that model.

References:

• [mlflow.register_model — MLflow 1.22.0 documentation]
• [MLflow Model Registry — Databricks Documentation]
• [Manage MLflow Models — Databricks Documentation] Message has links.

 To read data from a stream source, such as Kafka, socket, or rate, the spark.readStream method should be used instead of spark.read. The spark.readStream method returns a streaming DataFrame that represents the unbounded input data stream. The spark.readStream method supports the same options and formats as the spark.read method, such as schema, delta, csv, json, etc. The spark.readStream method can also read from a Delta table as a stream source, by specifying the format("delta") and the path or table name of the Delta table123

The other options are incorrect because:

• A. Replacing “inference” with the path to the location of the Delta table does not change the fact that spark.read is used to read from a stream source, which is not supported. The spark.readStream method should be used instead, and the path or table name of the Delta table can be specified as an option or argument.
• B. Replacing schema(schema) with option("maxFilesPerTrigger", 1) does not change the fact that spark.read is used to read from a stream source, which is not supported. The spark.readStream method should be used instead, and the schema can be specified as an option or argument. The option("maxFilesPerTrigger", 1) is an optional configuration that limits the number of files processed in each trigger for file-based stream sources, such as delta, csv, json, etc. It does not affect the reading of data from a stream source4
• D. Replacing format("delta") with format("stream") does not change the fact that spark.read is used to read from a stream source, which is not supported. The spark.readStream method should be used instead, and the format can be specified as an option or argument. The format("stream") is not a valid format for reading data from a stream source. The supported formats are delta, kafka, socket, rate, etc1
• E. Replacing predict with a stream-friendly prediction function does not change the fact that spark.read is used to read from a stream source, which is not supported. The spark.readStream method should be used instead, and the prediction function can be applied to the streaming DataFrame as usual. The predict function does not need to be changed, as long as it can accept a streaming DataFrame as input and return a column of predictions as output5

References:

• Input Sources - Structured Streaming Programming Guide - Spark 3.2.0 Documentation
• Structured Streaming + Delta Lake - Databricks
• Structured Streaming Programming Guide - Spark 3.2.0 Documentation
• Configuration - Structured Streaming Programming Guide - Spark 3.2.0 Documentation
• Machine Learning with Structured Streaming - Databricks

The MLflow Model Registry provides a centralized model store, set of APIs, and UI, to collaboratively manage the full lifecycle of an MLflow Model. It provides model lineage, model versioning, model aliasing, model tagging, and annotations. The Model Registry defines four model stages that represent the lifecycle of a model: None, Staging, Production, and Archived. Each model stage has a different meaning and purpose:

• None: This is the default stage when a new model version is registered. It indicates that the model version is not ready for any downstream use cases and needs further development or testing.
• Staging: This stage indicates that the model version is ready for testing or validation in a pre-production environment. It can be used for quality assurance, user acceptance testing, or performance evaluation before moving to production.
• Production: This stage indicates that the model version is ready for deployment in a production environment. It can be used for serving predictions, scoring data, or supporting business decisions. Only one model version per registered model can be in the production stage at a time.
• Archived: This stage indicates that the model version is no longer in active use and can be safely deleted or moved to a long-term storage. It can be used for historical or audit purposes, or for restoring a previous model version if needed.

References:

• MLflow Model Registry Documentation, p. 1-2
• Introducing the MLflow Model Registry - Databricks, p. 1-2
• Manage MLflow Models — Databricks Documentation, p. 1-2