What is Data Cardinality? - Data warehousing
What is Data Cardinality?Cardinality is the term used in database relations to denote the occurrences of data on either side of the relation.
There are 3 basic types of cardinality:
High data cardinality:
Values of a data column are very uncommon.
e.g. email ids and the user names
Normal data cardinality:
Values of a data column are somewhat uncommon but never unique.
e.g. A data column containing LAST_NAME (there may be several entries of the same last name)
Low data cardinality:
Values of a data column are very usual.
e.g. flag statuses: 0/1
Determining data cardinality is a substantial aspect used in data modeling. This is used to determine the relationships.
Types of cardinalities:
The Link Cardinality - 0:0 relationships
The Sub-type Cardinality - 1:0 relationships
The Physical Segment Cardinality - 1:1 relationship
The Possession Cardinality - 0: M relation
The Child Cardinality - 1: M mandatory relationship
The Characteristic Cardinality - 0: M relationship
The Paradox Cardinality - 1: M relationship.