Cubes are logical representation of multidimensional data. The edge of the cube contains dimension members and the body of the cube contains data values. The linking in cube ensures that the data in the cubes remain consistent.

A number of very small dimensions might be lumped together to form a single dimension, a junk dimension ‐ the attributes are not closely related. Grouping of Random flags and text attributes in a dimension and moving them to a separate sub dimension is known as junk dimension.

Surrogate key is a substitution for the natural primary key. It is just a unique identifier or number for each row that can be used for the primary key to the table. The only requirement for a surrogate primary key is that it is unique for each row in the table. It is useful because the natural primary key can change and this makes updates more difficult. Surrogated keys are always integer or numeric.

If a table contains the values, which is neither dimension nor measures is called degenerate dimensions.

ER modeling is used for normalizing the OLTP database design.
Dimensional modeling is used for de‐normalizing the ROLAP/MOLAP design.