I was asked this question in an interview.
What is the drawback of using 3rd Normal form in databases?
I know its main advantages which are
1. Duplication is reduced
2. Data integrity
Is there any Drawback of using 3rd Normal form?
Third normal form is violated when a non-key field is a fact about another non-key field, as in
| EMPLOYEE | DEPARTMENT | LOCATION |
The EMPLOYEE field is the key. If each department is located in one place, then the LOCATION field is a fact about the DEPARTMENT -- in addition to being a fact about the EMPLOYEE. The problems with this design are the same as those caused by violations of second normal form:
To satisfy third normal form, the record shown above should be decomposed into the two records:
| EMPLOYEE | DEPARTMENT |
| DEPARTMENT | LOCATION |
So The answer to your question is In the unnormalized form, the application searches one record type. With the normalized design, the application has to search two record types, and connect the appropriate pairs.So there is some possible performance cost for certain retrieval applications