Community Q&A

DP-750 — frequently asked questions

Community-vetted answers to 38 common questions about this exam, each traced back to a specific practice question.

Questions from real practice questions

Each Q&A comes from a specific question — follow the link for the full analysis

How Should You Configure Compute for Databricks Telemetry Ingestion?

Why is moving telemetry ingestion to shared compute wrong here?

Shared compute is interactive and mixes workloads across users, so it cannot guarantee production isolation or per-run autoscaling for scheduled, non-interactive telemetry pipelines.

Does Photon alone satisfy the autoscaling requirement?

No. Photon is a performance accelerator; autoscaling comes from running ingestion on an autoscaling job compute cluster instead of a fixed-node all-purpose cluster.

How to create Unity Catalog assets table in finance.procurement?

Why does the DP-750 answer use USE CATALOG finance before USE SCHEMA procurement?

The assets table must be created in finance.procurement, so the session must first switch the current catalog to finance, then set the current schema to procurement.

Can CREATE TABLE finance.procurement.assets replace USE CATALOG and USE SCHEMA?

It is valid fully qualified syntax, but the exhibit provides separate USE CATALOG and USE SCHEMA targets, so the expected drag values are finance, procurement, and assets.

Configuring Azure Databricks Cluster Autoscaling and Termination

Why is disabling Photon acceleration not the best way to minimize costs?

Disabling Photon can significantly slow down query execution, leading to longer runtimes and potentially higher total compute costs, offsetting any DBU savings.

Does specifying a fixed number of workers help with cost minimization?

No, fixing the worker count prevents the cluster from scaling down during low activity, leading to wasted resources and higher costs compared to using autoscaling.

How to Optimize a Growing Delta Table with Frequent Updates and Deletes?

Why choose Liquid clustering over partitioning for CustomerId and EventDate filters?

Liquid clustering handles high-cardinality columns and evolving filter patterns without re-partitioning, while partitioning on CustomerId would create too many small files and degrade performance.

How do deletion vectors reduce the effort of frequent updates and deletes?

Deletion vectors mark rows as deleted without rewriting full Parquet files, so compliance updates and deletes complete faster and with less write amplification.

Optimize Azure Databricks Cluster Costs for Predictable Workloads

Why not just use Spot Instances?

Spot Instances can save up to 90% but introduce interruption risks. For critical batch workloads where reliability is key, right-sizing reserved/on-demand nodes via fewer workers is safer.

Does disabling autoscaling affect performance?

No, because the workload is predictable and does not spike. Autoscaling is designed for variable loads; removing it for stable loads simply stops paying for unused reserve capacity.

Lakeflow SDP Compute Configuration for DP-750

Why not use a job cluster for Lakeflow SDP?

Job clusters require manual management and setup. Serverless compute automates provisioning and scaling, significantly reducing administrative effort.

Is serverless compute suitable for continuous streaming pipelines?

Yes, serverless compute supports continuous processing modes required by streaming pipelines in Lakeflow SDP while optimizing costs via pay-per-use.

Implementing ALM with Databricks Asset Bundles

Why not use Terraform for deploying notebooks?

Terraform manages cloud infrastructure resources. While it can deploy some Databricks objects, Asset Bundles are the native, optimized tool for managing notebooks, jobs, and workflows via Git.

What is the benefit of parameterizing targets?

It allows the same bundle definition to be deployed to different environments (dev, prod) with specific variables (like cluster sizes or endpoints) without changing the core code.

Can a Single-Node Databricks Runtime ML Cluster Use GPUs or Distribute Workloads?

Does Databricks Runtime ML automatically enable GPU acceleration on a general purpose node type?

No. Databricks Runtime ML includes GPU-capable libraries, but GPU acceleration requires a GPU-enabled VM node type; a general purpose node has no GPU to accelerate.

Why can't a single-node Azure Databricks cluster distribute an ML training workload?

A single-node cluster runs only a driver with no worker nodes, so there are no executors to spread tasks across; distributed training needs a multi-node cluster with workers.

Where to Add Genie Synonym Instructions for Sales1

Why is adding instructions to Sales1 or Schema1 wrong here?

Genie instructions are stored on the Genie space, not on tables or schemas, so guidance placed on Sales1 or Schema1 would not scope queries to Space1 and could leak across spaces.

How do instructions keep other Genie spaces unaffected?

Instructions are private to each Genie space, so editing Space1's instructions changes only that space's query routing while all other spaces keep their own settings.

How should Notebook1 read storageKey from kv-secure at runtime?

Does a Key Vault-backed secret scope in Databricks cache the storageKey value?

No. dbutils.secrets.get resolves storageKey from kv-secure on each call, so Notebook1 always sees the value the cloud security team last published.

Which Azure Key Vault permission does the Databricks workspace need to read storageKey?

Only read access to the secret (Get). List, write, delete or Secrets Officer roles are not needed for retrieval and violate least privilege.

How to remove Delta files and logs after 90 days in Unity Catalog?

Why not set delta.logRetentionDuration to 90 days for the transaction logs?

The hotspot allows only one property; delta.deletedFileRetentionDuration is the one that lets VACUUM reclaim deleted data files. Log retention can be managed separately.

Does VACUUM make a Delta table unavailable while it runs?

No. VACUUM runs online and readers can query the table; unreferenced files are removed after the retention threshold.

Delta Retention Properties for Auditing Deleted Data

Why isn't delta.deletedFileRetentionDuration alone enough to meet the requirement?

The transaction log (_delta_log) is a separate retention track with its own 30-day clock. Without delta.logRetentionDuration, the history of the deletions can age out independently, breaking the audit trail for the deleted customer data.

Why is delta.enableDeletionVectors wrong here even though deleted rows stay readable?

Deletion vectors mark rows as deleted but keep the underlying files indefinitely, so nothing is removed permanently without a manual REORG TABLE step. That fails the automatic 30-day permanent-removal requirement and increases administrative effort.

Unity Catalog GRANT for Table Creation, Query, and Modify Without Grant Rights?

Why can't I grant ALL PRIVILEGES on schema1 to group1?

ALL PRIVILEGES includes MANAGE, which allows group1 to grant permissions, violating the 'cannot grant permissions' requirement.

Does group1 need USE CATALOG on catalog1 to create tables in schema1?

Yes, USE CATALOG on catalog1 is required to access the catalog before using schema1 and creating tables.

Which authentication and volume permission for an external Unity Catalog volume?

For the external volume, is the Azure Databricks Access Connector itself the authentication type?

No — the connector is the Azure resource that carries the identity. The authentication is the managed identity it uses, which is why that is the credential-free dropdown choice.

Which privilege lets users read files in Volume1 without modifying them?

READ VOLUME on Volume1 (plus USE CATALOG and USE SCHEMA on its parents). WRITE VOLUME would allow modification and breaks least privilege.

Lakeflow Connect vs. External Tables in Unity Catalog

How do I expose SQL Server tables without copying data?

Use Unity Catalog Foreign Catalogs or create external tables using the SQL Server JDBC connection.

What is Lakeflow Connect used for if not external access?

It is used for ingesting and transforming data by moving it into Databricks-managed Delta tables.

Which ingestion options match Contoso's data sources in DP-750?

Why is Auto Loader recommended for both telemetry and maintenance logs?

Both sources are file-based in ADLS Gen2 and require schema drift handling; Auto Loader provides incremental ingestion with schema evolution and exactly-once semantics.

Why not use Lakeflow Connect for external weather data?

The weather data comes from a custom REST API; a Databricks notebook allows custom HTTP calls, while Lakeflow Connect is typically for supported databases and SaaS apps.

How Do You Stream Change Data Feed Inserts, Updates and Deletes from a Delta Table?

Why does ignoreChanges = true fail when readChangeFeed = true is set on db1.sales_orders?

The two options conflict. ignoreChanges is the deprecated Delta streaming setting and Databricks raises an error when it is combined with a CDF read; use skipChangeCommits instead.

Which _change_type values does the CDF stream emit for db1.sales_orders?

insert, update_preimage, update_postimage and delete. The preimage/postimage pair lets the downstream pipeline replay each update deterministically.

Azure Databricks Table Profiling for Null Value Tracking

Why isn't a snapshot profile sufficient for this task?

A snapshot only provides a static view of data at one moment. It cannot inherently track or display changes over time as new records are added.

Does a time series profile require a TIMESTAMP column?

While ideal, the exam scenario focuses on the functional need to track progression. In practice, time series profiles leverage versioning or timestamps to show metric evolution.

Azure Databricks Lakeflow SDP Pipeline Expectations

Do pipeline expectations stop the pipeline if a record is invalid?

No. In Lakeflow SDP, failed expectations prevent the specific invalid record from being written to the target table and send it to quarantine, allowing the rest of the pipeline to complete successfully.

Why is Option D incorrect for minimizing development effort?

Option D requires writing custom code to identify, filter, and store bad records. Option C uses built-in declarative syntax, which is significantly faster to implement and maintain.