"dcrespo" <dcrespo@xxxxxxxxx> writes: > They are exactly the same, that's why I want to evaluate it only once > and, depending on it, put the corresponding value into two different > fields that must be returned, instead of evaluating once for each > field. Any insight? There's no solution that wouldn't cost you more than double evaluation, for such a simple expression. The general solution is to use two levels of SELECT: select ..., x, x, ... from (select ..., big-expr as x, ... from ... offset 0) ss; You need the "offset 0" (which is otherwise a no-op) to prevent the planner from folding the two selects into a single level and ending up with two copies of big-expr anyway. The runtime overhead associated with the extra plan level is about going to eat up whatever you might save in this example, though with a seriously expensive expression (for instance, a function that does some fairly expensive SELECT itself) you might find it worth doing. regards, tom lane
