What do you mean by fat tables?

A fat table is a database table that contains a large number of columns, often including many denormalized or redundant fields. These tables are called "fat" because they store a lot of information in a single row. While they can simplify queries by reducing joins, they can also lead to performance issues such as increased I/O, slower query times, and higher storage costs. Fat tables are common in data warehouses or reporting systems where quick read access is prioritized over strict normalization. However, they can become problematic when the schema changes frequently or when the table grows too large, making maintenance and indexing difficult. A better approach is to normalize the data into smaller, related tables and use views or materialized views for reporting.