Size matters
Always use the smallest data size that will accommodate the largest
possible value. If a column is going to store values between 1 and 5,
use tinyint instead of int.
This rule also applies to character columns. The smaller the data
size, the less there is to read, so performance, over all, benefits.
In addition, smaller size reduces network traffic. With newer
technology, this tip seems less relevant, but don’t dismiss it out of
hand. You’ll won’t regret being efficient from the get-go.
For more info visit http://www.techrepublic.com/blog/10-things/10-plus-tips-for-getting-the-best-performance-out-of-your-sql-server-data-types/
