Snowflake schema

The snowflake schema is represented by centralized fact tables which are connected to multiple dimensions.

Normalization therefore tends to increase the number of tables that need to be joined in order to perform a given query, but reduces the space required to hold the data and the number of places where it needs to be updated if the data changes.

Snowflake schemas, in contrast to flat single table dimensions, have been heavily criticised.

Their goal is assumed to be an efficient and compact storage of normalised data but this is at the significant cost of poor performance when browsing the joins required in this dimension.

[4] This disadvantage may have reduced in the years since it was first recognized, owing to better query performance within the browsing tools.