In a Data Warehouse system, a Fact table is simply a table that holds all of the facts or business information that can be exposed to reporting and analysis when needed. Fields that reflect direct facts, as well as foreign fields that connect the fact table to other dimension tables in the Data Warehouse system, are stored in these tables. Depending on the model type used to construct the Data Warehouse, a Data Warehouse system can have ONE or more fact tables.

Following are the three types of fact tables:-

• Transactional Fact Table: This is a very basic and fundamental view of corporate processes. It can be used to depict the occurrence of an event at any given time. The facts measure are only valid at that specific time and for that specific incident. "One row per line in a transaction," according to the grain associated with the transaction table. It typically comprises data at the detailed level, resulting in a huge number of dimensions linked with it. It captures the smallest or atomic level of dimension measurement. This allows the table to provide users with extensive dimensional grouping, roll-up, and drill-down reporting features. It's packed yet sparse at the same time. It can also be big at the same time, depending on the number of events (transactions) that have occurred.
• Snapshot Fact Table: The snapshot depicts the condition of things at a specific point in time, sometimes known as a "picture of the MOMENT." It usually contains a GREATER number of non-additive and semi-additive information. It aids in the examination of the company's overall performance at regular and predictable times. Unlike the transaction fact table, which adds a new row for each occurrence of an event, this represents the performance of an activity at the end of each day, week, month, or any other time interval. However, to retrieve the detailed data in the transaction fact table, snapshot fact tables or periodic snapshots rely on the transaction fact table. The periodic snapshot tables are typically large and TAKE up a lot of space.
• Accumulating Fact Table: These are used to depict the activity of any process with a well-defined beginning and end. Multiple data stamps are commonly found in accumulating snapshots, which reflect the predictable stages or events that occur over the course of a lifespan. There is sometimes an EXTRA column with the date that indicates when the row was last updated.