.

Hereof, what is fact table and what are different types of fact table?

If you stay true to the grain, then all of your fact tables can be grouped into just three types: transaction grain, periodic snapshot grain and accumulating snapshot grain (the three types are shown in Figure 1). In Figure 1, the dimensions are designated by FK (foreign key) and the numeric facts are italicized.

Subsequently, question is, can we join two fact tables directly? As per best practice for dimensional data modeling it is always suggested that 2 fact tables should never be joined directly (i.e PK and FK join) instead should only be joined through conformed dimensions.

Also question is, what are fact and dimension tables?

The fact table mainly consists of business facts and foreign keys that refer to primary keys in the dimension tables. A dimension table consists mainly of descriptive attributes that are textual fields. On the contrary, a fact table contains a foreign key, measurements, and degenerated dimensions.

What is the granularity of fact tables?

The granularity is the lowest level of information stored in the fact table. The depth of data level is known as granularity. In date dimension the level could be year, month, quarter, period, week, day of granularity. The factors of determination will be resent to the requirements.