Microsoft DP-750 - Implementing Data Engineering Solutions Using Azure Databricks

The correct answers are B and E.

The goal is to reduce storage costs while preserving 30 days of time travel. Two actions are needed:

Set delta.deletedFileRetentionDuration to a value aligned with the 30-day requirement (Option B). Note: the answer option states ' 10 days ' which would be insufficient for 30-day time travel — in practice this property should be set to at least 30 days. This property defines the retention floor: VACUUM will not delete any file newer than this threshold.

Run VACUUM on Table1 (Option E). VACUUM physically removes unreferenced data files older than the retention duration from storage. Without running VACUUM, obsolete files accumulate indefinitely regardless of the retention property setting — the property tells VACUUM what to keep; VACUUM is what does the actual cleanup.

Option C (OPTIMIZE) compacts small files for better query performance but never deletes anything. Option D (logRetentionDuration) keeps the transaction log for time travel but doesn ' t free up the data file storage.

Two settings address the overlapping-run problem:

Concurrent Runs policy set to ' Skip ' (or ' Allow only one concurrent run ' ). When a new scheduled trigger fires while the previous run is still in progress, the new run is skipped rather than starting alongside the ongoing one. This prevents two runs from writing to the same tables at the same time — which is the data corruption risk the question highlights.

Cron-based schedule for the hourly trigger. A cron expression defines the regular execution cadence. Combined with the concurrency setting, the job runs hourly but never overlaps.

An alternative to ' Skip ' is ' Wait ' (queue the new run), which ensures every scheduled run eventually executes — but for this scenario where overlapping is the primary concern, skipping the missed run is typically preferable to building up a queue of back-to-back executions.

A file arrival trigger starts Job1 when new files are detected in the monitored Azure Storage location. Because the job is launched only after a qualifying arrival, compute does not remain active while the source is idle. This is well suited to unpredictable file-delivery patterns and avoids the unnecessary executions produced by a fixed schedule. A continuous trigger keeps the workload running and therefore consumes compute even when no files are available. A scheduled trigger starts the job at predetermined times whether or not new data exists. A manual trigger cannot provide automatic processing. File arrival triggers consequently provide the required event-driven behavior while improving resource utilization and controlling cost during inactive periods. Microsoft Learn

A time series profile repeatedly calculates data-quality metrics as a table changes and preserves those measurements over time. This makes it possible to observe whether the number of null values in each column is increasing, decreasing, or remaining stable as new records are added. A snapshot profile evaluates the table at a particular point in time and is therefore insufficient when the requirement is to analyze metric progression across multiple updates. Inference is associated with deriving information such as a schema or statistical characteristics; it is not the profile type used to maintain a historical sequence of monitoring measurements. Because the question requires repeated evaluation and the ability to observe changes throughout the dataset’s progression, the time series profile satisfies both requirements.

The correct answer is C — File Arrival trigger.

File Arrival monitors a specified Azure Storage path and fires a job run each time a new file lands there. This ticks both requirements: Job1 starts automatically in response to new data (no human involvement), and when no files arrive, no job runs — no cluster spins up, no compute cost is incurred.

Option A (scheduled) runs at fixed intervals regardless of whether files are waiting. A quiet weekend still kicks off hourly (or daily) runs, burning compute for nothing. Option B (continuous) keeps the job running perpetually, consuming resources even during long gaps between file arrivals — exactly what ' does NOT consume compute resources when no data is available ' rules out. Option D (manual) requires a person to trigger every run, which is unsuitable for unpredictable arrival patterns.

A Databricks notebook provides the flexibility required to implement complex, highly customized Python and PySpark transformations. Scheduling that notebook as a Lakeflow Jobs task supplies native daily orchestration, monitoring, retries, and compute management without introducing another service. Azure Data Factory data flows are oriented toward visually designed transformations and would add external orchestration complexity for logic already implemented most naturally in Python. A continuous job is inappropriate because the workload runs once per day rather than continuously. Spark Declarative Pipelines is effective for declarative batch and streaming ETL, but it is less direct when the core requirement emphasizes highly customized procedural Python transformations. A notebook task therefore provides the necessary programming freedom while keeping scheduling and operation inside Azure Databricks.

The correct answer is A — merge.

A Git merge combines the histories of two branches by creating a merge commit that joins them. Every individual commit from Branch1 remains visible in the repository log — the full development history is preserved. This is the requirement: ' the solution must preserve the commit history in the repository. '

Option C (rebase) moves Branch1 ' s commits on top of main by replaying them as new commits with new hashes. The end result looks like a linear history, but the original commit hashes are rewritten — the prior history is not preserved in its original form. For a shared repository, rebase rewrites public history, which is considered problematic.

Option B (pull) fetches remote changes and merges or rebases them into the current branch — it ' s used to sync with a remote, not to incorporate a feature branch. Option D (push) sends local commits to the remote but doesn ' t incorporate any branch into another.

The correct answer is A. Photon is Azure Databricks ' native vectorized query engine, written in C++, designed to accelerate data ingestion and SQL-heavy workloads significantly over the standard Spark JVM path. Enabling it on a job compute cluster directly addresses Contoso ' s requirement for ' fast and consistent performance for BI workloads ' and ' production ingestion workloads that can scale automatically during telemetry spikes. '

Photon integrates transparently — no code changes are needed — and pairs well with autoscaling job clusters to handle the bursty 40,000-sensor telemetry load.

Option B contradicts the isolation requirement: Contoso explicitly needs production and development separated, not merged onto shared compute. Option C with a fixed large node gives peak capacity at all times, driving up costs even during quiet periods. Option D disabling autoscaling is the opposite of what ' s needed — telemetry spikes require elastic scaling, not a locked node count.

The right ingestion tool depends on the source characteristics:

File-based telemetry and maintenance data → Auto Loader (cloudFiles). It monitors ADLS Gen2 for new arrivals, handles schema inference and evolution for the frequent schema drift, and requires minimal operational effort.

Real-time telemetry from Event Hubs → Spark Structured Streaming with the azure-eventhubs-spark connector. This provides exactly-once semantics and checkpoint-based recovery, satisfying ' resume processing after failures without reprocessing. '

Structured maintenance data from PostgreSQL → JDBC connector. Databricks supports direct JDBC reads from relational databases with pushdown predicates.

Daily CSV ERP extracts (50–100 GB) → COPY INTO or Auto Loader. Both support idempotent incremental batch loading into Delta tables with minimal code.