A document database is a NoSQL database that stores each record as a self-describing document, usually JSON or a similar format, which can contain nested fields and arrays.
Why it matters
Documents map naturally to objects in application code, and related data can be embedded together so one read returns everything needed. That removes many joins and suits catalogs, content management, and user profiles. The trade-off is duplicated data and weaker support for cross-document relationships, so modeling around your access patterns is essential.
Example
{
"_id": "order-1001",
"customer": { "id": 7, "name": "Ravi" },
"items": [
{ "sku": "A-100", "qty": 2 },
{ "sku": "B-220", "qty": 1 }
]
}In a relational model this order would span three tables.
Common mistakes
- Embedding data that is also edited elsewhere, causing stale copies.
- Letting documents grow endlessly, such as an ever-expanding array of events.
- Treating schemaless as meaning no validation. Use schema validation rules where available.
Related
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