DP-900 Describe core data concepts Practice Test 7 — 15 Questions

Question 1

A healthcare application stores patient medical history in a relational database. The system must ensure that after a transaction updates multiple records (e.g., diagnosis and medication), all changes are saved or none are saved. This property is best described as:

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. In the context of a relational database storing patient medical history, if a transaction updates both the diagnosis and medication records, atomicity guarantees that either both updates are committed or both are rolled back, preventing partial updates that could leave the data in an inconsistent state.

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Consistency

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Durability

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Isolation

Question 2

A marketing company collects data from social media feeds including text posts, images, and videos. The data arrives in various formats with no fixed structure or schema. This type of data is best described as:

Accepted Answer

C) Unstructured data. Unstructured data lacks a predefined data model or schema, making it ideal for storing text posts, images, and videos that arrive in varied formats. Unlike structured or semi-structured data, unstructured data cannot be easily organized into rows and columns or parsed with tags, which is why option C is correct for this scenario.

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A) Structured data

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B) Semi-structured data

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D) Relational data

Question 3

A banking system processes a money transfer between two accounts. The system is designed so that after the transaction is committed, the results are permanently saved and survive any subsequent system failure, such as a power outage. Which ACID property ensures this behavior?

Accepted Answer

Durability. Durability ensures that once a transaction is committed, its changes are permanently stored and survive system failures, such as power outages or crashes. In this banking scenario, the money transfer results are written to non-volatile storage (e.g., disk) via a write-ahead log, guaranteeing that the committed state is recoverable even after a restart.

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Atomicity

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Consistency

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Isolation

Question 4

A retail company collects data from online transactions including order ID, customer details, product IDs, quantities, and timestamps. The data is stored in a relational database and used for order processing and inventory management. Which characteristic of this data makes it structured?

Accepted Answer

It is stored in rows and columns with a predefined schema.. Structured data is defined by a fixed schema where each entity (e.g., orders) is stored in rows and columns with predefined data types (e.g., INT for order ID, VARCHAR for customer details). This relational model enforces consistency and enables efficient querying via SQL for order processing and inventory management.

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It is stored as key-value pairs.

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It is stored in JSON format with variable fields.

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It is stored in unstructured text files.

Question 5

A database administrator is explaining to a colleague that a database transaction must ensure that either all operations within it succeed or none of them take effect. Which ACID property is being described?

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work: either all operations within it are committed successfully, or none are applied. This is the property that guarantees the 'all-or-nothing' behavior described in the question. In Azure SQL Database or SQL Server, atomicity is enforced through the transaction log and the write-ahead logging (WAL) protocol, which records changes before they are written to disk.

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Consistency

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Isolation

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Durability

Question 6

A company stores customer data in a relational database. The database design includes a rule that every order must be associated with a valid customer ID that exists in the Customers table. This rule is an example of which data concept?

Accepted Answer

Referential integrity. Referential integrity ensures that relationships between tables remain consistent. In a relational database, a foreign key constraint enforces that every order's customer ID must match an existing customer ID in the Customers table, preventing orphaned records. This rule directly implements referential integrity as defined by the SQL standard (e.g., via FOREIGN KEY constraints).

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Data normalization

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Entity integrity

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Data consistency

Question 7

A social media application displays the number of posts each user has created. After a user submits a new post, the count must reflect the update across all servers within a few seconds. Which data consistency model best describes this requirement?

Accepted Answer

Eventual consistency. Eventual consistency is correct because the requirement allows a few seconds for the update to propagate across all servers, meaning the system does not guarantee immediate uniformity but will converge to the same count eventually. This is typical in distributed systems like social media applications where high availability and partition tolerance are prioritized over immediate consistency, often using techniques like asynchronous replication.

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Strong consistency

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Sequential consistency

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Causal consistency

Question 8

A logistics company collects data from fleet sensors. Each sensor sends a JSON message containing the vehicle ID, timestamp, and a variable set of measurements such as engine temperature, tire pressure, and fuel level. The structure of the JSON message differs between sensor types and sometimes includes optional fields. How should this data be classified?

Accepted Answer

Semi-structured data. The data is semi-structured because it conforms to a schema (JSON format with fields like vehicle ID and timestamp) but allows variability in structure, such as optional fields and different sets of measurements per sensor type. This flexibility is a hallmark of semi-structured data, which does not require a rigid tabular schema like structured data but still contains tags or markers to separate data elements.

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Structured data

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Unstructured data

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Relational data

Question 9

A logistics company collects sensor data from delivery trucks. Each sensor sends a JSON message that includes a fixed set of core fields (truck ID, timestamp) but also includes optional fields such as temperature, humidity, and engine diagnostics depending on the sensor type. The JSON structure varies between messages. How should this data be classified?

Accepted Answer

Semi-structured data. The JSON messages contain a fixed set of core fields (truck ID, timestamp) but also include optional fields that vary per message, meaning the data has a flexible schema. This mixture of structured fields and variable attributes is the defining characteristic of semi-structured data, which does not require a rigid schema like a relational table but still has organizational properties (e.g., key-value pairs). In Azure, this type of data is commonly stored in services like Azure Cosmos DB or Azure Blob Storage with JSON format.

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Structured data

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Unstructured data

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Relational data

Question 10

A company receives customer order data from its online store in a CSV file. Each line contains fields like OrderID, CustomerName, Product, Quantity, and OrderDate. This data is best described as:

Accepted Answer

Structured data. A is correct because the CSV file contains data that conforms to a strict tabular schema with predefined columns (OrderID, CustomerName, Product, Quantity, OrderDate) and consistent data types per column. This rigid, row-and-column format with a fixed schema is the defining characteristic of structured data, which can be directly loaded into a relational database or Azure SQL Database without transformation.

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Semi-structured data

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Unstructured data

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Transactional data

Question 11

A company stores product information such as product ID, name, price, and category in a relational database with rows and columns. This data is best described as:

Accepted Answer

Structured data. Structured data conforms to a predefined schema with rows and columns, making it easily searchable and queryable via SQL. The product information (ID, name, price, category) fits this model exactly, as each attribute has a fixed data type and is stored in a relational database table.

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Semi-structured data

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Unstructured data

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Transactional data

Question 12

A database system must ensure that when a transfer of funds between two accounts is processed, if the system crashes after debiting the first account but before crediting the second, the database automatically undoes the debit. This property is best described as:

Accepted Answer

Atomicity. Atomicity ensures that a transaction is treated as a single, indivisible unit of work. If the system crashes after debiting one account but before crediting the other, the database's transaction log records the partial changes, and during recovery, the database engine (e.g., SQL Server's ARIES recovery model) performs an automatic rollback of the uncommitted transaction, undoing the debit to maintain atomicity.

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Consistency

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Isolation

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Durability

Question 13

A company stores employee records in a database. Each employee record contains an EmployeeID (unique), Name, Department, and HireDate. The EmployeeID is used to uniquely identify each employee. Which data concept does the EmployeeID represent?

Accepted Answer

Primary key. The EmployeeID is used to uniquely identify each employee record, which is the defining characteristic of a primary key. In relational databases, a primary key enforces entity integrity by ensuring each row has a unique, non-null identifier. This aligns with the core data concept of a primary key as the unique identifier for a table.

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Index

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Foreign key

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Unique constraint

Question 14

A healthcare application stores patient medical history in a relational database. The system must ensure that after a transaction updates multiple records (e.g., diagnosis and medication), all changes are saved or none are saved. This property is best described as:

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Semi-structured. The data is semi-structured because it is stored as JSON documents, which have a flexible schema that can vary between records (e.g., new optional fields can be added). JSON documents are self-describing and do not require a fixed schema like relational tables, but they still have organizational properties (fields like PatientID, Timestamp) that distinguish them from unstructured data like plain text or images. The application's queries on specific fields (PatientID, Timestamp) further confirm the data has structure, but the schema flexibility rules out structured or relational classifications.

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Structured

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Unstructured

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Relational

Question 15

A company has a database that processes millions of small credit card transactions per second for payment authorization. They also need to run complex reports that aggregate transaction data over months to detect fraud patterns. Which type of workload describes the payment authorization process?

Accepted Answer

OLTP (Online Transaction Processing). The payment authorization process involves high-volume, low-latency transactions that read, insert, and update individual records in real time. This is the classic definition of OLTP (Online Transaction Processing), which is optimized for ACID-compliant, row-based operations on current data. The scenario explicitly states 'millions of small credit card transactions per second,' which aligns with OLTP workloads like order entry or banking.

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OLAP (Online Analytical Processing)

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HTAP (Hybrid Transactional/Analytical Processing)

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ETL (Extract, Transform, Load)