Re: Indexing a Bit String column

Gregory Stark <stark@enterprisedb.com> writes:
> Note that something like "WHERE myBitStringCol & B'101'" might be selecting
> too much of your table to make an index useful anyways. If each bit is set in
> half the table then you're talking about selecting 3/4 of the table in which
> case a full table scan would be more efficient than any index.

If the expectation is that the bitstring is mostly zeroes, I wonder
whether the OP wouldn't be better off using an integer-array
representation, ie instead of '00000101' store '{6,8}'.  Then he could
use the existing GIST or GIN support for integer array operations.

            regards, tom lane