For a scientific project of mine I am developing (in C#4 and T-SQL) an application potentially meant to handle very big quantities of very simple records performing simple operations with them (a scientific simulation engine, not a linear time-series cruncher). I’d like to use 64-bit integers as primary keys for better capacity.
I am going to integrate using of Entity Framework, POCO collections and arrays processing and T-SQL stored procedures practically.
I am going to store a database on an SQL Server 2008 and access it from multiple application instances simultaneously for distributed processing.
SQL Server and application instances are going to be run on 32-bit Windows XP systems, sometimes on completely 64-bit-unaware hardware.
What penalties am I going to face for using 64-bit integer types as primary keys?
As long as you stick to reading and writing those numbers (ie no arithmetic, just database queries), the performance hit will be negligible. It will be like using 2
ints as parameters instead of 1.Once you start doing arithmetic on them however, it starts to get messy. Addition and subtraction is roughly 3 times as slow as for normal
ints. Multiplication and division is a LOT slower, over an order of magnitude. I posted the code for multiplying 2 64-bit numbers on a 32-bit cpu somewhere on this site, I could look it up if you want, but it’s over 3 pages long.Seeing how you’re talking about ID fields however, you shouldn’t be doing any arithmetic on them right? So you should be fine.