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diff --git a/doc/unit-7.md b/doc/unit-7.md index cf471a0..e9edc2f 100644 --- a/doc/unit-7.md +++ b/doc/unit-7.md @@ -250,6 +250,17 @@ A common grain would be each business transaction, such as an individual line it Clicks on a website is possibly the lowest level of granularity. +Size of the fact table + +The grain and duration of the fact table have a direct impact on the size of that table. + +We can estimate the number of rows in the fact table as follows: + +1. Estimate the number of possible values for each dimension associated with the fact table. +2. Multiple the values obtained in the first step after making any necessary adjustments + +Total rows = 1000 stores * (10,000 products * 50% = 5,000) * 24 months + = 120,000,000 rows Multiple fact tables |