Data engineering·Modelling for analysis
getting the product's category name means joining the fact to product, then product to subcategory, then subcategory to category.
Snowflake schema
Also calledsnowflaked dimensions, normalised dimensions
A star whose dimensions have been normalised into their own sub-tables, so hierarchies are separate rows rather than repeated columns. It saves storage and makes a hierarchy edit a single update, at the price of more joins in every query and more ways for an analyst to get one wrong. On modern columnar storage the space saving is close to irrelevant, which is why the star usually wins and the snowflake survives mainly where a hierarchy is genuinely volatile.