0
What are the types of Schemas we have in data warehouse and what are the difference between them?

Open 1 Answers 37 Views Technology

What are the types of Schemas we have in data warehouse and what are the difference between them?

1 Answer

0

There are three different data models that exist.

  1. Star schemaStar-schema-informatica-interview-questionsHere, the Sales fact table is a fact table and the surrogate keys of each dimension table are referred here through foreign keys. Example: time key, item key, branch key, location key. The fact table is surrounded by the dimension tables such as Branch, Location, Time and item. In the fact table there are dimension keys such as time_key, item_key, branch_key and location_keys and measures are untis_sold, dollars sold and average sales.Usually, fact table consists of more rows compared to dimensions because it contains all the primary keys of the dimension along with its own measures.
  2. Snowflake schema
    Snowflake-schema-informatica-interview-questions
    In snowflake, the fact table is surrounded by dimension tables and the dimension tables are also normalized to form the hierarchy. So in this example, the dimension tables such as location, item are normalized further into smaller dimensions forming a hierarchy.
  3. Fact constellations
    Fact-constellations-informatica-interview-questions
    In fact constellation, there are many fact tables sharing the same dimension tables. This examples illustrates a fact constellation in which the fact tables sales and shipping are sharing the dimension tables time, branch, item.
by (279k points)
...