Re: number of rows estimation for bit-AND operation

2009/8/20 Slava Moudry <smoudry@4info.net>:
> Hi,
> Yes, I thought about putting the bit-flags in separate fields.
> Unfortunately - I expect to have quite a lot of these and space is an issue when you are dealing with billions of
recordsin fact table, so I prefer to pack them into one int8. 

For giggles I created two test tables, one with a single int, one with
8 bools, and put 100M entries in each.  The table with 8 bools took up
aprrox. 3560616 bytes, while the one with a single int took up approx.
3544212

I.e they're about the same.  You should really test to see if having a
lot of bools costs more than mangling ints around.  I'm guessing I
could fit a lot more bools in the test table due to alignment issues
than just 8.