DP-203 Design and implement data storage Practice Question
This DP-203 practice question tests your understanding of design and implement data storage. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
Refer to the exhibit.
```
CREATE EXTERNAL DATA SOURCE SalesData
WITH (
LOCATION = 'https://datalakegen2.dfs.core.windows.net/sales',
CREDENTIAL = StorageCred
);
CREATE EXTERNAL FILE FORMAT ParquetFormat
WITH (
FORMAT_TYPE = PARQUET,
DATA_COMPRESSION = 'org.apache.hadoop.io.compress.SnappyCodec'
);
CREATE EXTERNAL TABLE dbo.Sales (
SaleID INT,
ProductID INT,
SaleDate DATE,
Amount DECIMAL(10,2)
)
WITH (
LOCATION = '/year=2024/',
DATA_SOURCE = SalesData,
FILE_FORMAT = ParquetFormat
);
```
You are examining a T-SQL script that creates an external table in Azure Synapse serverless SQL pool. The query SELECT * FROM dbo.Sales returns zero rows, but the folder /year=2024/ in ADLS Gen2 contains Parquet files. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The credential used to access ADLS Gen2 does not have sufficient permissions.
Option A is correct because the most common reason for SELECT * FROM an external table returning zero rows despite data existing in the underlying ADLS Gen2 folder is that the serverless SQL pool lacks the necessary permissions to read the Parquet files. The credential used in the external data source must have at least 'Storage Blob Data Reader' role on the storage account or the container, and the identity (e.g., SAS token, service principal, or managed identity) must be correctly configured. Without this, the query executes successfully but returns no rows because the pool cannot access the data.
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.
✓
The credential used to access ADLS Gen2 does not have sufficient permissions.
Why this is correct
Insufficient permissions (e.g., missing Storage Blob Data Reader role) cause zero rows.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The serverless SQL pool does not support reading Parquet files.
Why it's wrong here
Serverless SQL pool supports Parquet.
✗
The external table definition is missing the SCHEMA_NAME parameter.
Why it's wrong here
SCHEMA_NAME is optional.
✗
The DATA_COMPRESSION setting is incompatible with Parquet files.
Why it's wrong here
Snappy compression is standard for Parquet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume a missing or misconfigured schema parameter (like SCHEMA_NAME) would cause zero rows, but in reality, permission issues are the primary cause of empty results when the data path is correct and the file format is supported.
Detailed technical explanation
How to think about this question
Under the hood, serverless SQL pool uses a distributed query engine that reads data directly from ADLS Gen2 via the Hadoop Distributed File System (HDFS) driver. The credential defined in the external data source is used to authenticate against Azure Storage; if the credential lacks read permissions, the engine cannot list or read files, resulting in an empty result set rather than an error. A real-world scenario is when a SAS token expires or a managed identity is not assigned the 'Storage Blob Data Reader' role on the storage account, causing silent failures.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-203 question in full detail.
Design and implement data storage — This question tests Design and implement data storage — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The credential used to access ADLS Gen2 does not have sufficient permissions. — Option A is correct because the most common reason for SELECT * FROM an external table returning zero rows despite data existing in the underlying ADLS Gen2 folder is that the serverless SQL pool lacks the necessary permissions to read the Parquet files. The credential used in the external data source must have at least 'Storage Blob Data Reader' role on the storage account or the container, and the identity (e.g., SAS token, service principal, or managed identity) must be correctly configured. Without this, the query executes successfully but returns no rows because the pool cannot access the data.
What should I do if I get this DP-203 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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