The cardinal rules of SQL
When working with SQL, especially when optimizing it, you can come across the term 'high-cardinality column'. What does it mean?
A: The column data is referenced by many other tables.
B: The column data references many other tables.
C: It is a measure for the uniqueness of the data in the column.
D: The column fields can contain much data (f.i. BLOB or text fields)