Emmanuel Turlay

@sheerun I have a table dedicated to users settings with dozens of booleans columns and as many rows as users. That freaks me out. I much rather like a single integer field on the users table.
I never need to query on them, I only need to check a given record's settings.

Now to be clear, I never said people should use this technique blindly. Everyone should be sensible to how it fits there requirements. Just like everything else.
Also, I used ruby here to illustrate the point but the post was mostly intended to showcase the technique rather than the language used to apply it.

@sheerun Why?

@encodes Indeed.
I actually learned this technique while coding for the ATLAS experiment at CERN which contains thousands of electronic chips where both physical and logical space are limited resources.

* sudo rm -rf /*

- don't forget to run

Indeed, using bitmasks requires some serious testing.
And you sure can't use it for everything. In my case, I use it for a stupid collection of checkboxes.

That's a fair point.
If I'm not mistaken, all flavours of SQL support bitwise operations don't they? Hence one could query with SELECT * FROM users WHERE settings & (1 << 3) > 0.
Isn't that right?

@jeroenr Thank you for that tip, I was looking for that exactly ;)