So much for text information. Let's go on to something that computers really excel at - numbers!
Remember your education at school? You didn't learn all types of numbers at once. In the kindergarten, you learned natural numbers (1,2,3). Then, at school, you were taught fractions (1/3, 3/5 or 0.2, 0.7) and then negative numbers (-3, -4.5). At some point, you could have learned real numbers (e.g. Π, √ 2).
Why weren't you taught all the numbers at once? Because some of them are simple and some of them more complex. Fraction calculations are more difficult than calculating natural numbers. It's easier to add 1 + 2 than 3/2 + 4/5.
The same applies to databases. They can make calculations faster if they know what kind of numbers they have to compute.