The correct first step is to verify that the serverless SQL pool has been granted the Storage Blob Data Reader role on the storage account. This is because the “external table not accessible” error in Azure Synapse serverless SQL pool almost always stems from an authorization failure when the pool’s service identity tries to read the underlying Parquet files in Azure Data Lake Storage Gen2. Without this role assignment at the storage account scope, the SQL pool cannot authenticate, even if the external table definition is syntactically correct. On the DP-203 exam, this scenario tests your understanding that serverless SQL pool uses its own managed identity for storage access, not the user’s credentials—a common trap is assuming that creating the external table with proper LOCATION and FILE_FORMAT is enough. Remember the memory tip: “Serverless needs a role, not just a goal.”
DP-203 Develop data processing Practice Question
This DP-203 practice question tests your understanding of develop data processing. 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 myDataSource
WITH (
LOCATION = 'https://mystorageaccount.dfs.core.windows.net/mycontainer'
);
CREATE EXTERNAL FILE FORMAT myFileFormat
WITH (
FORMAT_TYPE = PARQUET,
DATA_COMPRESSION = 'org.apache.hadoop.io.compress.SnappyCodec'
);
CREATE EXTERNAL TABLE dbo.Sales (
SaleID int,
ProductName varchar(100),
SaleDate date,
Amount decimal(10,2)
)
WITH (
LOCATION = 'sales/',
DATA_SOURCE = myDataSource,
FILE_FORMAT = myFileFormat
);
Refer to the exhibit. You have created an external table in Azure Synapse Analytics serverless SQL pool to query Parquet files stored in Azure Data Lake Storage Gen2. When you query the external table, you get an error that the external table is not accessible. What should you check first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify that the serverless SQL pool has been granted the 'Storage Blob Data Reader' role on the storage account.
The error 'external table is not accessible' in Azure Synapse serverless SQL pool typically indicates an authorization failure when the SQL pool attempts to read the underlying Parquet files in Azure Data Lake Storage Gen2. Serverless SQL pool uses its own service identity to access storage, and it must be granted the 'Storage Blob Data Reader' role on the storage account at the storage account scope to have read permissions. Without this role assignment, the SQL pool cannot authenticate to the storage, resulting in the access error.
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.
✗
Check that the external table's LOCATION path is relative to the container and does not start with a slash.
Why it's wrong here
The LOCATION path 'sales/' is correct as a relative path.
✓
Verify that the serverless SQL pool has been granted the 'Storage Blob Data Reader' role on the storage account.
Why this is correct
The serverless SQL pool needs read permissions on the storage account to access the data.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Ensure that the external file format is correctly referencing the Parquet format.
Why it's wrong here
The file format definition is correct.
✗
Confirm that the Snappy compression codec is supported by the serverless SQL pool.
Why it's wrong here
Snappy is supported for Parquet files.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'external table not accessible' with file path or format issues, but the error message specifically points to a permissions/authorization problem, not a configuration or syntax error.
Detailed technical explanation
How to think about this question
Under the hood, serverless SQL pool uses a distributed query engine that accesses Azure Data Lake Storage Gen2 via the Azure Blob Filesystem (ABFS) driver. The ABFS driver authenticates using OAuth 2.0 with the managed identity of the serverless SQL pool, and the 'Storage Blob Data Reader' role grants the necessary 'Microsoft.Storage/storageAccounts/blobServices/containers/blobs/read' permission at the Azure RBAC level. Without this role, the ABFS driver receives HTTP 403 (Forbidden) responses, which the SQL pool surfaces as an 'external table is not accessible' error. In a real-world scenario, if you have multiple storage accounts, you must assign this role on each account that the serverless SQL pool queries.
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.
Develop data processing — This question tests Develop data processing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Verify that the serverless SQL pool has been granted the 'Storage Blob Data Reader' role on the storage account. — The error 'external table is not accessible' in Azure Synapse serverless SQL pool typically indicates an authorization failure when the SQL pool attempts to read the underlying Parquet files in Azure Data Lake Storage Gen2. Serverless SQL pool uses its own service identity to access storage, and it must be granted the 'Storage Blob Data Reader' role on the storage account at the storage account scope to have read permissions. Without this role assignment, the SQL pool cannot authenticate to the storage, resulting in the access error.
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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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