Re: pgbench more operators & functions
От | Fabien COELHO |
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Тема | Re: pgbench more operators & functions |
Дата | |
Msg-id | alpine.DEB.2.20.1610041941150.24533@lancre обсуждение исходный текст |
Ответ на | Re: pgbench more operators & functions (Robert Haas <robertmhaas@gmail.com>) |
Список | pgsql-hackers |
Hello Robert, > I think it's pretty clear that this patch is not Ready for Committer, As a reviewer, I do not know when to decide to put something as "ready". My opinion is that it is a matter of the reviewer to decide. Whether some consensus is actually reached, or whether a committer is going to disagree later on, cannot be helped. > because there's no consensus that we want this, and like Tom and > Stephen, I'd argue that there are large parts of it we don't want. > The documentation in the latest patch version mentions XOR and IF > which we definitely don't want because there is no similar thing in > SQL, I have removed these and put CASE WHEN THEN ELSE END instead in v6. > but in addition to that, I don't think much of an argument has > been made that any of this is actually useful. In the TPC-B benchmark, some conditional is needed because under some probability an account must be chosen in the *same* branch as the teller, otherwise in the *other* branches. > I'm skeptical about the notion that giving pgbench a vast repertoire of > mathematical functions is a good idea. What does that actually let us > do that is useful and not possible today? I do not see a vast "repertoire" of functions. There are "usual" int operators, logical operators, and a few functions. About the one added in this patch: bitwise operations: I have seen some use to create a non uniform random from a random one. Once one operator is put in, there is no reason not to put the others... exp & ln: could be used to tweak distributions. conditional: see above. I have not put trigonometric functions because I could not think of a use in a benchmarking context. > I'm happy to see pgbench made better in a variety of ways, but I don't > really see why that particular thing is useful. Perhaps I'm just > missing something. I'm trying to add features that are IMO useful for benchmarking. When doing so, someone says "hay, you put a double expression, you must put double variables". Although I can see the point of double expressions for passing ints into some transformations, I can't see a double variable really useful in any benchmark, but there it is, it is a side effect of the process, and it is somehow to have orthogonal features. -- Fabien.
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