On Thu, Apr 24, 2008 at 3:01 PM, Tino Wildenhain <tino@xxxxxxxxxxxxx> wrote: > Merlin Moncure wrote: > > I think you're being a little too hard on enums here. I was actually > > in the anti-enum camp until it was demonstrated to me (and in my own > > testing) that using enum for natural ordering vs. fielding the > > ordering of the type out to a join is can be a huge win in such cases > > where it is important. Relational theory is all well and good, but in > > practical terms things like record size, index size, and query > > performance are important. > > > > Uhm. Sorry what? Can you demonstrate this particular use? > When I first saw discussion about enumns I kinda hoped they > will be implemented as kind of macro to really map to a table. > But here you go. I'm still looking for a good example to > demonstrate the usefullness of enums (same for arrays for that > matter) You must not be aware that enums are naturally ordered to make that statement. Suppose your application needs to order a large table by a,b,c where b is the an 'enum' type of data. With an enum, the order is inlined into the key order, otherwise it's out of line, meaning your you key is larger (enum is 4 bytes, varchar is guaranteed to be larger), and you need to join out to get the ordering position, use a functional index, or cache it in the main table. I agree with disagree with you on arrays. I think they are generally a bad idea in terms of using them as a column type. However they are useful passing data to/from functions and back/forth from the client. merlin
