DP-203 Develop data processing Practice Question
You are working with Azure Synapse Analytics serverless SQL pool. You need to query a set of Parquet files located in ADLS Gen2. The files have nested columns (structs and arrays). Which function should you use to flatten the nested data?
⚠ Common exam trap
Many exam-takers confuse CROSS APPLY with a flattening function, but CROSS APPLY only invokes a table-valued function (like OPENJSON) and does not flatten data by itself.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
OPENJSON
OPENJSON is the correct function because it parses JSON text and returns objects and properties from JSON input as rows and columns. In Azure Synapse serverless SQL pool, when Parquet files contain nested columns (structs and arrays), they are exposed as JSON strings, and OPENJSON can flatten these nested structures into a relational format. This allows you to query complex nested data directly without needing to pre-process the files.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
OPENJSON
Why this is correct
OPENJSON can parse nested JSON structures and flatten them into rows.
- ✗
PIVOT
Why it's wrong here
PIVOT is for converting rows to columns, not flattening nested data.
- ✗
UNNEST
Why it's wrong here
UNNEST is not a T-SQL function; it exists in other SQL dialects like PostgreSQL.
- ✗
CROSS APPLY
Why it's wrong here
CROSS APPLY is used with table-valued functions, but not specifically for flattening nested columns in Parquet.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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