> On Mon, Mar 14, 2022 at 11:02:16AM -0400, Robert Haas wrote: > On Mon, Mar 14, 2022 at 10:57 AM Dmitry Dolgov <9erthali...@gmail.com> wrote: > > Well, yeah, the commit message is somewhat clumsy in this regard. It > > works almost in the way you've described, except if the list is all > > constants and long enough to satisfy the threshold then *first N > > elements (where N == threshold) will be jumbled -- to leave at least > > some traces of it in pgss. > > But that seems to me to be a thing we would not want. Why do you think > otherwise?
Hm. Well, if the whole list would be not jumbled, the transformation would look like this, right? WHERE x in (1, 2, 3, 4, 5) -> WHERE x in (...) Leaving some number of original elements in place gives some clue for the reader about at least what type of data the array has contained. Which hopefully makes it a bit easier to identify even in the collapsed form: WHERE x in (1, 2, 3, 4, 5) -> WHERE x in (1, 2, ...) > > I'm not sure if I follow the last point. WHERE x in (1,3) and x = > > any(array[1,3]) are two different things for sure, but in which way are > > they going to be mixed together because of this change? My goal was to > > make only the following transformation, without leaving any uncertainty: > > > > WHERE x in (1, 2, 3, 4, 5) -> WHERE x in (1, 2, ...) > > WHERE x = any(array[1, 2, 3, 4, 5]) -> WHERE x = any(array[1, 2, ...]) > > I understand. I think it might be OK to transform both of those > things, but I don't think it's very clear either from the comments or > the nonexistent documentation that both of those cases are affected -- > and I think that needs to be clear. Not sure exactly how to do that, > just saying that we can't add behavior unless it will be clear to > users what the behavior is. Yep, got it.
