DP-900 Describe core data concepts Practice Question
A social media company stores user profiles as JSON documents where each profile may have different attributes (e.g., some profiles include 'education' while others include 'work history'). The company also stores user-generated posts in a relational database table with fixed columns (PostID, UserID, Content, Timestamp). Which of the following best describes the data types used for user profiles and user posts?
⚠ Common exam trap
Candidates often confuse 'semi-structured' with 'unstructured' because JSON looks like free-form text, but JSON actually has a defined key-value structure, making it semi-structured, not unstructured.
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
✓
User profiles are semi-structured data; posts are structured data.
User profiles are stored as JSON documents with varying attributes, which is a classic example of semi-structured data because it has some organizational properties (key-value pairs) but does not enforce a fixed schema. User posts are stored in a relational database table with fixed columns (PostID, UserID, Content, Timestamp), which is structured data because it adheres to a rigid schema with defined data types and relationships.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
User profiles are structured data; posts are unstructured data.
Why it's wrong here
User profiles cannot be structured, because structured data requires every record to have the same defined columns, but JSON profiles frequently omit or add fields, so they lack a uniform schema. Posts are not unstructured either: although the text content is free-form, each post is defined by a fixed relational record with typed metadata fields like author ID, like count, and posting time, which is the opposite of unstructured data. Therefore, both classifications in this option are wrong.
When this WOULD be correct
This option would be correct if user profiles had a fixed schema (e.g., always same attributes) and posts were free-text without a fixed schema (e.g., stored as plain text files).
- ✓
User profiles are semi-structured data; posts are structured data.
Why this is correct
User profiles are semi-structured because JSON documents allow variable attribute sets—some users may have 'verified' while others have 'pronouns'—so there is no fixed schema, but the data still carries self-describing key-value pairs. Posts, in contrast, are stored in a fixed relational schema with consistent columns such as post_id, user_id, content, and created_timestamp, making them classic structured data. This combination makes the statement correct.
- ✗
Both are semi-structured data.
Why it's wrong here
The first half is correct—profiles are semi-structured—but the claim that posts are also semi-structured fails because posts follow a rigid pre-defined schema in a relational database, with the same fields present for every record. Semi-structured data is characterized by schema flexibility and nested or self-describing elements, whereas a structured post schema allows no per-record variation. Since posts cannot have arbitrary new fields from row to row, they cannot be classified as semi-structured.
When this WOULD be correct
This option would be correct if both datasets were stored as JSON documents with varying attributes (e.g., user profiles and posts both in a NoSQL document store) and no fixed schema enforced.
- ✗
User profiles are unstructured data; posts are structured data.
Why it's wrong here
Profiles are not unstructured data: unstructured data lacks an internal structure or organization, such as raw text or images, but JSON profiles contain keys, values, and a hierarchy, so they are semi-structured. The second half about posts is accurate, as they are structured, but that does not rescue the option because the profile classification is incorrect. Thus, an option that mislabels profiles as unstructured is wrong even if it correctly identifies posts as structured.
When this WOULD be correct
If the question described user profiles as free-text fields (e.g., 'bio' with no schema) and posts as images or videos without metadata, then profiles would be unstructured and posts would be unstructured as well, but this option would be correct if posts were structured (e.g., fixed columns).
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The DP-900 exam frequently reuses these exact scenarios with slightly different constraints.
✓User profiles are semi-structured data; posts are structured data.Correct answer▾
Why this is correct
User profiles are semi-structured because JSON documents allow variable attribute sets—some users may have 'verified' while others have 'pronouns'—so there is no fixed schema, but the data still carries self-describing key-value pairs. Posts, in contrast, are stored in a fixed relational schema with consistent columns such as post_id, user_id, content, and created_timestamp, making them classic structured data. This combination makes the statement correct.
✗User profiles are structured data; posts are unstructured data.Wrong answer — click to see why▾
Why this is wrong here
User profiles are JSON documents with varying attributes, which is semi-structured data, not structured. Posts have fixed columns, which is structured data, not unstructured.
★ When this WOULD be the correct answer
This option would be correct if user profiles had a fixed schema (e.g., always same attributes) and posts were free-text without a fixed schema (e.g., stored as plain text files).
Why candidates choose this
Candidates may confuse 'structured' with 'organized' and think JSON is structured, or they may not distinguish between semi-structured and structured data.
✗Both are semi-structured data.Wrong answer — click to see why▾
Why this is wrong here
User posts are stored in a relational database with fixed columns (PostID, UserID, Content, Timestamp), making them structured data, not semi-structured. Only user profiles (JSON with varying attributes) are semi-structured.
★ When this WOULD be the correct answer
This option would be correct if both datasets were stored as JSON documents with varying attributes (e.g., user profiles and posts both in a NoSQL document store) and no fixed schema enforced.
Why candidates choose this
Candidates may confuse 'semi-structured' with 'unstructured' or think that JSON always implies semi-structured, but they overlook that the posts have a fixed relational schema, making them structured.
✗User profiles are unstructured data; posts are structured data.Wrong answer — click to see why▾
Why this is wrong here
User profiles are JSON documents with varying attributes, which is the definition of semi-structured data, not unstructured. Posts have fixed columns, making them structured data, not unstructured.
★ When this WOULD be the correct answer
If the question described user profiles as free-text fields (e.g., 'bio' with no schema) and posts as images or videos without metadata, then profiles would be unstructured and posts would be unstructured as well, but this option would be correct if posts were structured (e.g., fixed columns).
Why candidates choose this
Candidates may confuse JSON with unstructured data because JSON is not a traditional relational format, or they may think that any data without a fixed schema is unstructured, ignoring that JSON has a defined structure (key-value pairs).
Analysis generated from the official DP-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Data Roles and Core Concepts
Key term
Data
Data is raw, unprocessed information, like numbers, words, or measurements, that can be stored, processed, and analyzed by computers.
Key term
Table
A table is a structured collection of data organized into rows and columns, used in databases and spreadsheets to store and manage information efficiently.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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