Re: update performance

El Mar 13 Feb 2001 16:53, Jonathan Leffler escribi': > > I don't fully understand the question, but I'll take a stab at it > anyway. > > UPDATE YourTable SET BoolColumn = 1 > WHERE BoolColumn = 0 AND ...whatever other conditions you need... > UPDATE YourTable SET BoolColumn = 0 > WHERE BoolColumn = 1 AND ...whatever other (different) conditions... Yes, this is what I worte. The other condition you put there is a bool_id IN (....) and in the programing script I build the list of ids. > If the processing has to scan the table anyway, then updating the > columns even when not needing to be changed may even be quicker than > double scanning the table; that depends on the other conditions, any > indexes, and so on. That was what I was asking. How would the performance of the update be if I do it in two updates with 2 conditions or with 2 updates with one condition each? I mean what consumns more resources, the update of the row, or the search? Saludos... ;-) -- System Administration: It's a dirty job, but someone told I had to do it. ----------------------------------------------------------------- Mart'n Marqu's email: martin@math.unl.edu.ar Santa Fe - Argentina http://math.unl.edu.ar/~martin/ Administrador de sistemas en math.unl.edu.ar -----------------------------------------------------------------