Data Redundancy & Data Duplication

Question 1

Redundancy

Answer 1

Data redundancy occurs when the same data is entered in to two or more fields of a database
For example, “Joe” is entered in to the Name field under a record called Customers
“Joe” is also entered in to the Customer field under a record called Purchases
Although we are referring to the same Joe in both fields, each piece of data is seen as unique
This means that to update “Joe”, we need to manually edit each reference
This can cause problems in database systems such as data anomalies
This differs from data duplication, as it is often not intentional and can take up potentially required storage space

Question 2

Data Duplication

Answer 2

Data duplication occurs when an exact copy of a piece of data is created
For example, copy and pasting an item called “MyPicture.jpg”
The new pasted item contains the exact same data as the original picture
On different Operating Systems, the naming convention for copies will change (e.g. “MyPicture 2.jpg” or “MyPicture copy.jpg”)
Data duplication provides benefits such as providing us with the ability to back up copies of files and create multiple versions of a file (which may be required for progress reporting or other information)
The duplication of data is often intentional and used primarily for creating backups
Data duplication on a database may result in data redundancy, and thus an inefficient and inconsistent database

Question 3

Why is it important?

Answer 3

The act of normalising a database (organizing data to prevent redundancy) is critical to maintain an efficient and clean database
Ensuring unnecessary data doesn’t reside on the database allows for a consistent and accurate database
The ability to duplicate data intentionally allows us to create backups and maintain our data