TSQL: Which real number type results in faster comparisons

Question

Among TSQL types (MSSQL): real, float and decimal; which type would result in faster comparisons?

Would decimal use hardaware FPU computation or is it purely in software?

Answer 1

Decimals cannot use the FPU. You get best performance with float or real which map to a standard IEEE floating point number which is supported by the FPU.

float = double real = single

Of course, single is faster.

Answer 2

Are these relative comparisons >, < or equality comparisons =, != ?

Floats and reals are approximation data types where as a decimal is an actual representation. If you're doing equality, you'll want to stay away from floats and reals. So that leaves decimals.

More than likely, SQL Server won't go to the FPU for relative comparisons. FPU and other coprocessors are used for arithmetic.