Cristian Veronesi <c.veronesi@xxxxxxx> writes: > If I try to use a function that returns the current time instead, a > sequential scan is always performed: > ... > Any suggestion? 1. Use something newer than 7.4 ;-) 2. Set up a dummy range constraint, ie select ... where ora_rif > localtimestamp and ora_rif < 'infinity'; The problem you have is that the planner doesn't know the value of the function and falls back to a default assumption about the selectivity of the '>' condition --- and that default discourages indexscans. (Note the very large estimate of number of rows returned.) In the range-constraint situation, the planner still doesn't know the value of the function, but its default assumption for a range constraint is tighter and it (probably) will choose an indexscan. Since PG 8.0, the planner understands that it's reasonable to pre-evaluate certain functions like localtimestamp to obtain better-than-guess values about selectivity, so updating would be a better fix. regards, tom lane
