DP-900 Describe core data concepts Practice Test 4 — 15 Questions

Question 1

A ride-sharing company processes trip requests from customers. Each trip is recorded as a single transaction that updates the driver's status, calculates the fare, and logs the ride. At the end of each month, the company runs reports that aggregate millions of trips to determine average wait times and revenue per driver. Which pair of terms best describes these two distinct workloads?

Accepted Answer

OLTP and OLAP. The first workload (trip request processing) is a classic OLTP (Online Transaction Processing) system because each trip is a single, atomic transaction that updates driver status, calculates fare, and logs the ride in real time. The second workload (monthly aggregation reports) is OLAP (Online Analytical Processing) because it queries millions of historical trip records to compute averages and revenue summaries. These two patterns have fundamentally different data storage and query optimization requirements, making OLTP and OLAP the correct pair.

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Batch processing and stream processing

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ETL and ELT

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Relational and non-relational

Question 2

A bank processes online fund transfers. Each transaction must ensure that either both the debit from the sender's account and the credit to the receiver's account occur, or if any part fails, the entire transaction is rolled back. Which ACID property does this guarantee?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this fund transfer scenario, atomicity guarantees that both the debit and credit operations either complete successfully together or are fully rolled back if any part fails, preventing partial updates that could leave the system in an inconsistent state.

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Consistency

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Isolation

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Durability

Question 3

A data analyst receives a dataset containing customer order details stored in a CSV file, a JSON file with product reviews, and a folder of JPEG images of products. Which of the following correctly categorizes these data types from most structured to least structured?

Accepted Answer

CSV → JSON → JPEG. CSV files are highly structured with rows and columns defined by a schema, making them the most structured. JSON files are semi-structured, using key-value pairs and nested objects that allow flexibility but lack a fixed schema. JPEG images are unstructured binary data with no inherent schema, so the correct order from most to least structured is CSV → JSON → JPEG, making option C correct.

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CSV → JPEG → JSON

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JSON → CSV → JPEG

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JPEG → JSON → CSV

Question 4

A bank processes a fund transfer that involves deducting money from one account and crediting it to another. The system ensures that both operations succeed together or, if any part fails, the entire transaction is rolled back, leaving both accounts unchanged. Which ACID property does this scenario primarily guarantee?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this fund transfer scenario, both the debit and credit operations must complete successfully, or the entire transaction is rolled back, leaving the accounts unchanged. This all-or-nothing behavior is the defining characteristic of atomicity in ACID transactions.

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Consistency

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Isolation

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Durability

Question 5

In a banking application, a transaction transfers $100 from Account A to Account B. The system deducts $100 from Account A successfully, but due to a network error, the credit to Account B fails. The application rolls back the deduction from Account A, ensuring that neither account is affected. Which ACID property is being enforced?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In this scenario, the deduction from Account A and the credit to Account B must both succeed or both fail entirely. When the credit to Account B fails, the system rolls back the deduction from Account A, preserving the all-or-nothing nature of the transaction. This is the core behavior of atomicity in ACID-compliant database systems like Azure SQL Database or SQL Server.

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Consistency

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Isolation

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Durability

Question 6

A global social media application allows users to post updates and 'like' posts. The application is designed to prioritize availability and partition tolerance over strong consistency. As a result, when a user likes a post, the like count may not be immediately visible to all users, but it will eventually become consistent across all regions. Which consistency model does this application follow?

Accepted Answer

Eventual consistency. The application prioritizes availability and partition tolerance, which aligns with the eventual consistency model. In this model, updates (like a 'like' count) are propagated asynchronously across replicas, and while reads may return stale data temporarily, all replicas will converge to the same value over time. This is typical of NoSQL systems like Apache Cassandra or Amazon DynamoDB when configured with eventual consistency.

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Strong consistency

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Consistent prefix

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Bounded staleness

Question 7

A healthcare company stores patient records in a relational database with fixed columns (PatientID, Name, DOB, BloodType). Medical images such as X-rays are stored as DICOM files. Clinical notes are stored as free-text documents. Which of the following correctly classifies these data types from most structured to least structured?

Accepted Answer

Patient records (structured), DICOM files (semi-structured), Clinical notes (unstructured). Patient records in a fixed-column relational database are structured data because they conform to a rigid schema with defined data types. DICOM files are semi-structured because they contain a structured header with metadata tags (e.g., patient ID, study date) alongside an unstructured binary image payload. Clinical notes as free-text documents are unstructured because they lack a predefined schema or organization, making them difficult to query without natural language processing.

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Patient records (structured), DICOM files (structured), Clinical notes (unstructured)

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Patient records (semi-structured), DICOM files (unstructured), Clinical notes (structured)

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Patient records (unstructured), DICOM files (semi-structured), Clinical notes (structured)

Question 8

A healthcare organization is planning a data analytics platform. They will ingest data from various sources: structured patient records from a relational database, semi-structured JSON logs from medical devices, and unstructured physician notes as plain text files. Which characteristic of big data describes the different formats of data being ingested?

Accepted Answer

Variety. The question describes data in three distinct formats: structured (relational database), semi-structured (JSON logs), and unstructured (plain text). In big data terminology, 'Variety' specifically refers to the different types and formats of data being processed. This is a core concept in the 4 V's of big data, where Variety captures the heterogeneity of data sources and structures.

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Volume

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Velocity

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Veracity

Question 9

A retail chain collects sales data from all its stores at the end of each business day by exporting CSV files from each store's database. The data is then combined and analyzed to generate daily sales reports. Which type of data processing does this describe?

Accepted Answer

Batch processing. This describes batch processing because sales data is collected from each store at the end of the business day, exported as CSV files, and then combined and analyzed in a scheduled, non-continuous manner. Batch processing is ideal for large volumes of data that are processed at periodic intervals, such as daily sales reports, rather than requiring immediate action.

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Real-time processing

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Stream processing

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Interactive query

Question 10

A retail company receives real-time data from IoT sensors in its warehouses. Each sensor sends a JSON payload containing a device ID, timestamp, and temperature reading. A data engineer needs to classify this data for storage planning. Which data type best describes the JSON payload?

Accepted Answer

Semi-structured data. The JSON payload is considered semi-structured data because it has organizational properties (key-value pairs, nested structure) that provide a schema, but it does not conform to a rigid tabular schema like a relational database. JSON allows flexible fields and varying data types, which is characteristic of semi-structured data.

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Structured data

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Unstructured data

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Relational data

Question 11

A retail company stores product inventory data in a SQL database, customer reviews as JSON files, and product images as JPEG files. Which of the following accurately describes the types of data stored?

Accepted Answer

D. Structured, semi-structured, and unstructured data are stored.. The company stores product inventory data in a SQL database, which enforces a fixed schema (tables, rows, columns) and is therefore structured data. Customer reviews stored as JSON files are semi-structured because they have a flexible schema (key-value pairs) but no rigid table structure. Product images as JPEG files are unstructured because they lack any predefined schema or organization. Option D correctly identifies that all three data types are present.

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A. Only structured data is stored because the SQL database contains the primary records.

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B. Only semi-structured and unstructured data is stored because JSON and images are not purely structured.

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C. Only unstructured data is stored because images have no predefined schema.

Question 12

A company stores customer information in a SQL database with fixed columns (CustomerID, Name, Email). They also store scanned PDF contracts and product images in a file storage system. Which statement correctly describes the types of data mentioned?

Accepted Answer

The customer information is structured, and the files are unstructured.. Customer information stored in fixed columns (CustomerID, Name, Email) follows a strict schema with defined data types and relationships, making it structured data. Scanned PDF contracts and product images are binary files with no inherent schema or organization, fitting the definition of unstructured data. Option C correctly pairs these classifications.

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Both the customer information and the files are structured data.

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The customer information is semi-structured, and the files are unstructured.

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Both the customer information and the files are unstructured.

Question 13

A retail company stores data about their products in different formats. Product ID and price are stored in a relational database table. Product descriptions are stored as plain text files. Product images are stored as JPEG files. Which of the following best categorizes these data types in order?

Accepted Answer

Structured, unstructured, unstructured. Product ID and price in a relational database table are structured because they follow a fixed schema with rows and columns. Product descriptions as plain text files have no predefined structure, making them unstructured. Product images as JPEG files are also unstructured because they consist of binary data without a schema. Thus, the order is structured, unstructured, unstructured, which matches option B.

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Structured, semi-structured, unstructured

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Structured, semi-structured, structured

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Semi-structured, structured, unstructured

Question 14

A retail company maintains a database of customer information including CustomerID, Name, Address, and Phone. Each record follows the same fixed schema. This type of data is best described as:

Accepted Answer

Structured data. Structured data conforms to a fixed schema where each record has the same fields (CustomerID, Name, Address, Phone) and data types, making it ideal for relational database storage. This rigid, tabular format allows efficient querying using SQL and enforces consistency across all rows.

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Semi-structured data

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Unstructured data

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Relational data

Question 15

A data engineer loads raw log files into a storage system. The structure of the data is interpreted at the time of reading, allowing queries to apply schema on the fly without preprocessing. This approach is best described as:

Accepted Answer

Schema-on-read. Schema-on-read means the data is stored in its raw, unstructured form, and the schema is applied dynamically when the data is queried. This is exactly what happens when raw log files are loaded into a storage system like Azure Data Lake Storage and queried with tools like Azure Synapse Serverless SQL or Apache Spark, which infer the schema at query time without requiring preprocessing.

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Schema-on-write

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Data warehouse

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Data virtualization