On Sat, May 11, 2024 at 4:21 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > > The dependency is fairly simple. In the presence of multiple arrays on > > the same column, which must be contradictory/redundant, but cannot be > > simplified solely due to lack of suitable cross-type support, we have > > multiple arrays on the same index column. _bt_advance_array_keys wants > > to deal with this by assuming that the scan key order matches the > > array key order. > > I guess what is not clear to me is what you mean by "array key order". > Is that simply the order of entries in BTArrayKeyInfo[], or are there > additional assumptions/restrictions?
I simply mean the order of the entries in BTArrayKeyInfo[]. > > There's another problem along these lines, that seems at least as bad: > > queries involving contradictory >= and <= quals aren't recognized as > > contradictory during preprocessing. There's no reason why > > _bt_preprocessing_keys couldn't detect that case; it just doesn't > > right now. > > Ugh, how'd we miss that? I can take a look at this, unless you're > on it already. My draft skip scan/MDAM patch already deals with this in passing. So you could say that I was already working on this. But I'm not sure that I would actually say so myself; what I'm doing is tied to far more complicated work. I haven't attempted to write the kind of targeted fix that you're thinking of. It might still be worth writing such a fix now. I certainly have no objections. -- Peter Geoghegan
