Structured data follows a predefined model, like a database table where every record has the same typed fields. Unstructured data, such as emails, documents, photos, and video, has no such schema. Semi-structured data like JSON and XML sits in between, with tags or keys but flexible shape.
Why it matters
Structured data is easy to query with SQL. Unstructured data is estimated to make up most of what organizations hold, but needs techniques like NLP or computer vision to analyze. The format decides which storage fits: a data warehouse or a data lake.
Example
Structured: orders(id=17, total=49.90, country="IN")
Semi-structured: {"id": 17, "items": [{"sku": "A1"}]}
Unstructured: "Hi, my order arrived late and damaged..."You can validate the semi-structured form with a JSON validator.
Common misconceptions
- Unstructured data is useless. It often holds rich context, such as customer feedback.
- Structured means correct. A tidy table can still contain wrong values.
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