DP-900 Describe core data concepts Practice Question
This DP-900 practice question tests your understanding of describe core data concepts. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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:
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Atomicity ensures that a transaction is either fully completed or fully rolled back, matching the all-or-nothing requirement.
B
Consistency
Why wrong: Consistency ensures that a transaction brings the database from one valid state to another, but does not enforce the all-or-nothing property across multiple records.
C
Durability
Why wrong: Durability guarantees that committed changes persist even after a failure, not the all-or-nothing behavior during a transaction.
D
Isolation
Why wrong: Isolation ensures that concurrent transactions do not interfere with each other, which is not the focus of this scenario.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Atomicity
Why this is correct
Atomicity ensures that a transaction is either fully completed or fully rolled back, matching the all-or-nothing requirement.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Consistency
Why it's wrong here
Consistency ensures that a transaction brings the database from one valid state to another, but does not enforce the all-or-nothing property across multiple records.
✗
Durability
Why it's wrong here
Durability guarantees that committed changes persist even after a failure, not the all-or-nothing behavior during a transaction.
✗
Isolation
Why it's wrong here
Isolation ensures that concurrent transactions do not interfere with each other, which is not the focus of this scenario.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse atomicity with consistency, mistakenly thinking that 'all-or-nothing' is about maintaining data rules, when in fact atomicity is specifically about the transaction's indivisibility at the write level.
Trap categories for this question
Scenario analysis trap
Isolation ensures that concurrent transactions do not interfere with each other, which is not the focus of this scenario.
Detailed technical explanation
How to think about this question
Under the hood, atomicity is implemented via a transaction log (e.g., SQL Server's transaction log or PostgreSQL's WAL) that records every change before it is written to the data pages. If a failure occurs mid-transaction, the database engine uses the log during recovery to roll back any partially applied changes, ensuring atomicity. A real-world scenario is a bank transfer: if the debit succeeds but the credit fails, atomicity ensures the debit is also rolled back, preventing money from disappearing.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-900 question in full detail.
Describe core data concepts — This question tests Describe core data concepts — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this DP-900 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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