On Thu, Oct 12, 2006 at 11:25:25AM -0500, Jim C. Nasby wrote: > Yes, but it does one key thing: allows DBAs to fix problems *NOW*. See > also my comment below.
If I may argue in the other direction, speaking as one whose career (if we may be generous enough to call it that) has been pretty much exclusively on the operations end of things, I think that's an awful idea. There are two ways that quick-fix solve-the-problem-now hints are going to be used. One is in the sort of one-off query that a DBA has to run from time to time, that takes a long time, but that isn't really a part of regular application load. The thing is, if you already know your data well enough to provide a useful hint, you also know your data well enough to work around the problem in the short run (with some temp table tricks and the like). The _other_ way it's going to be used is as a stealthy alteration to regular behaviour, to solve a particular nasty performance problem that happens to result on a given day. And every single time I've seen anything like that done, the long term effect is always monstrous. Two releases later, all your testing and careful inspection and planning goes to naught one Saturday night at 3 am (because we all know computers know what time it is _where you are_) when the one-off trick that you pulled last quarter to solve the manager's promise (which was made while out golfing, so nobody wrote anything down) turns out to have a nasty effect now that the data distribution is different. Or you think so. But now you're not sure, because the code was tweaked a little to take some advantage of something you now have because of the query plans that you ended up getting because of the hint that was there because of the golf game, so now if you start fiddling with the hints, maybe you break something else. And you're tired, but the client is on the phone from Hong King _right now_. The second case is, from my experience, exactly the sort of thing you want really a lot when the golf game is just over, and the sort of thing you end up kicking yourself for in run-on sentences in the middle of the night six months after the golf game is long since forgotten. The idea for knobs on the planner that allows the DBA to give directed feedback, from which new planner enhancements can also come, seems to me a really good idea. But any sort of quick and dirty hint for right now gives me the willies. A -- Andrew Sullivan | [EMAIL PROTECTED] "The year's penultimate month" is not in truth a good way of saying November. --H.W. Fowler ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match