On Sat, Jan 31, 2009 at 1:33 PM, Gregory Stark <stark@enterprisedb.com> wrote:
> No index is going to be particularly effective for boolean columns unless
> they're very heavily skewed. You might find it useful to build separate
> partial indexes on other keys for each value though.
Not entirely true. If you've got a table where <1% of the rows are
one or the other, a partial index can be very useful on a bool.
Also, in the very odd case where you almost all the time select all
the true or all the false, a regular index can be useful for
reindexing the table on.
But yeah, if there's a relatively even mix of true and false, then a
bool index isn't much use.