Bit-wise function

[AndyMei]

Hi all,

Does VW support Ingres Bit-wise functions in the where clause? We would like to combine multiple bits as an int on a column, then filter out rows based on a bit mask.

If it's not supported, we are thinking split multiple bits as separate columns as char(1). Any better suggestion? Thanks.

Andy

[zelaine]

No, Ingres VectorWise currently does not support the Ingres bit functions.

What you've suggested doing sounds like a workable approach.

[rhann]

My IVW machine seems to be powered down at the moment and there's no one in the office to switch it on, so I'm only guessing this will work with IVW.

Ingres SQL allows you to do the calculations to get at individual bits albeit indirectly. If you have an INTEGER column called map, and you count bits from 0 starting at the low-order end, you can extract the value of bit 3 (i.e. the fourth bit) using ...WHERE mod(map/2**3,2)=1. If you want rows where the fourth bit and the twelth bit (bit 11) are set, you can use ...WHERE mod(map/2**3,2)=1 AND mod(map/2**11,2)=1, and so on.