What is a dimension table?
A dimension table is a table in a dimensional data model that holds descriptive, categorical context, such as customer, product, location or date, used to filter, group and label the measures stored in fact tables. Dimensions answer the who, what, when and where of an event.
If a fact table holds the numbers, dimension tables hold the words around them. A product dimension might list each product's name, category, brand and price tier; a date dimension might carry day, week, month, quarter and fiscal period for every date.
Dimension tables typically:
- Are wide but shorter than facts, with many descriptive columns.
- Have a primary key referenced by fact-table foreign keys.
- Enable slicing and dicing, group sales by category, filter by region, trend by fiscal quarter.
- May be slowly changing, tracking how attributes evolve over time.
Good dimensions make reports readable; messy ones make analysis painful, especially when column names are cryptic or dimensions live in a different system from the facts.
iDBQuery bridges that gap. Its semantic layer interprets dimension attributes even under obscure names, and its federation engine can join a fact table in one database to a dimension table in another source entirely. Ask a question in plain language and iDBQuery groups and filters by the right dimensions automatically, returning a cited answer that traces back to the underlying rows.
Updated 2026-06-22