"Dann Corbit" <[EMAIL PROTECTED]> writes: >> I've still got a problem with these checks; I think they are a net >> waste of cycles on average.
> The benchmarks say that they (order checks) are a good idea on average > for ordered data, random data, and partly ordered data. There are lies, damn lies, and benchmarks ;-) The problem with citing a benchmark for this discussion is that a benchmark can't tell you anything about real-world probabilities; it only tells you about the probabilities occuring in the benchmark case. You need to make the case that the benchmark reflects the real world, which you didn't. > If you trace the algorithms in a debugger you will be surprised at how > often the partitions are ordered, even with random sets as input. Well, I do agree that checking for orderedness on small partitions would succeed more often than on larger partitions or the whole file --- but the code-as-given checks all the way down. Moreover, the argument given for spending these cycles is that insertion sort sucks on reverse-order input ... where "sucks" means that it spends O(N^2) time. But it spends O(N^2) in the average case, too. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org