How can you use a bridge table in data warehousing?

3 How does a bridge table improve the query performance?

A bridge table improves the query performance by enabling faster joins and aggregations. For example, if you want to calculate the total sales amount by product category, you can join the fact table, the bridge table, and the product table, and group by the product category column. This query would be more efficient than joining the fact table and the product table directly, since the bridge table has fewer columns and a smaller size. Moreover, you can create indexes on the bridge table to speed up the join operations and filter conditions. Additionally, you can use a bridge table to support complex calculations, such as weighted averages or percentages, by storing the relevant measures in the bridge table.

4 How do you create a bridge table?

To create a bridge table, you need to follow some steps. First, you need to identify the tables that have a many-to-many or multivalued relationship, and the attributes that define the association. Second, you need to create a new table that contains the keys of the related tables, and any other attributes that are specific to the association. Third, you need to populate the bridge table with the data from the source tables, using queries or ETL tools. Fourth, you need to create indexes on the bridge table to optimize the queries. Fifth, you need to update the bridge table periodically to reflect the changes in the source tables.

5 What are the benefits and challenges of using a bridge table?

Using a bridge table has some benefits and challenges. The benefits include simplifying the data model, improving query performance, and supporting complex calculations. However, there are also challenges associated with bridge tables. These include increasing the number of tables in the data warehouse, introducing potential data quality issues, and requiring more skills and knowledge to design and implement the bridge table and queries.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?