> > > > As far as i can see, postgresql select a simple "INDEX SCAN using index" > > on table. > > That's because the index does not hold all the information. So INDEX > ONLY is impossible. > Thank you for your quick answer, but there is something a don't understand: the index holds all attributes' values (one index entry/one table entry). Right? given a query with only this attribute on SELECT clause, which is the missing information, that do not exist in index? ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match