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From Jason Kolb <jason.k...@gmail.com>
Subject Bitwise operations on row keys
Date Fri, 06 May 2011 16:42:43 GMT
Hi all,

I've been looking around for an answer to this and can't find anything so
far.

I have a need to find rows whose row key matches a bit mask. Specifically, I
would like to provide a 128-bit array as the row key when retrieving
columns, and be able to specify that the result of a bitwise AND operation
should be equal to the 128-bit array I passed in.

I looked at CASSANDRA-1472<https://issues.apache.org/jira/browse/CASSANDRA-1472>and
while the concept of using a bitmap is similar it seems that the
behavior I'm looking for is almost inverted from what is implemented there.
As far as I can tell this is a "traditional" bitmap index implementation,
each row being represented by a bit corresponding to its value for the
indexed column. I actually want to use a bitmap as the row key and do a
simple bitwise AND operation against it. I don't think the existing work in
progress will serve my needs, I think what I actually need is a modified row
scanning/reading code to do the bitwise comparison as records are read.

Assuming I'm understanding this properly, I'm willing to pitch in and help
if I can. Is there anyone here who can perhaps point me in the right
direction? I just want to make sure I'm not attempting the impossible or
going about it the wrong way.

Thanks,
Jason

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