Some designers create separate normalized dimensions for each level of a many-to- one hierarchy, such as a date dimension, month dimension, quarter dimension, and year dimension, and then include all these foreign keys in a fact table. This results in a centipede fact table with dozens of hierarchically related dimensions. Centipede fact tables should be avoided. All these fixed depth, many-to-one hierarchically related dimensions should be collapsed back to their unique lowest grains, such as the date for the example mentioned. Centipede fact tables also result when designers embed numerous foreign keys to individual low-cardinality dimension tables rather than creating a junk dimension.