< * Allow star join optimizations
<
<   While our bitmap scan allows multiple indexes to be joined to get
<   to heap rows, a star joins allows multiple dimension _tables_ to
<   be joined to index into a larger main fact table.  The join is
<   usually performed by either creating a cartesian product of all
<   the dimmension tables and doing a single join on that product or
<   using subselects to create bitmaps of each dimmension table match
<   and merge the bitmaps to perform the join on the fact table.  Some
<   of these algorithms might be patented.