DA0-002 Data Concepts and Environments Practice Question
Exhibit
{
"schema": {
"type": "struct",
"fields": [
{ "name": "id", "type": "int", "nullable": false },
{ "name": "name", "type": "string", "nullable": true },
{ "name": "email", "type": "string", "nullable": true }
]
}
}Refer to the exhibit. An Avro schema is defined as shown. Which data design concept does this represent?
⚠ Common exam trap
DA0-002 often tests the confusion between schema-on-write and schema-on-read — the trap is assuming that because Avro is flexible, it is schema-on-read, when in fact Avro enforces schema at write time.
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
✓
Schema-on-write
An Avro schema explicitly defines the structure and data types of records before data is written, which is the definition of schema-on-write. The schema is enforced at write time, ensuring data conforms to the defined format when stored. This contrasts with schema-on-read, where structure is applied only when data is queried.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Schema-on-read
Why it's wrong here
Schema-on-read applies structure when data is queried, so the schema is not enforced at write time; the exhibit defines a schema stored with the data, which is schema-on-write. It is tempting because schema-on-read suits flexible data lakes holding raw, unvalidated files.
- ✗
Schema-less design
Why it's wrong here
An Avro schema is explicitly declared in the exhibit, so the design is schema-on-write, not schema-less. Schema-less design suits document stores such as MongoDB, where no structure is enforced at write time and shape is inferred only on read.
- ✗
Dynamic schema
Why it's wrong here
The exhibit shows a fixed, declared Avro schema, which is static rather than dynamically inferred at read time. Dynamic schema applies to systems that derive structure from each incoming record, such as schema-on-read query engines over raw files.
- ✓
Schema-on-write
Why this is correct
Schema-on-write enforces the Avro schema at ingestion, validating each record before storage. This satisfies the exhibit's requirement that data conforms to a predefined structure, unlike schema-on-read, which defers interpretation until query time and permits malformed records to persist in the store.
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Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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