Shulou(Shulou.com)06/01 Report--

Star model: multiple dimension tables are connected by a fact table. The graph shows that it is like a star, and there is some data redundancy on the dimension table, as shown in the following figure:

In the above picture, our customer dimension table has a certain degree of data redundancy for the provinces, cities and counties stored by the customers. in order to solve this problem, the snowflake model is designed.

Snowflake model: in order to reduce data redundancy, dimensions are added to the dimension table on the basis of the star model to reduce data redundancy. As shown below:

In the figure above, we remove the customer dimension table of the county, city and province, add the administrative dimension table, and store only the county information in the administrative dimension table in the customer dimension table, which reduces the data redundancy, but although the data redundancy is reduced, but in practical application, the performance impact is relatively great, which is not as convenient and efficient as the star model.

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