Thanks to Timo for bringing up an interesting topic. Personally, "OPAQUE" doesn't seem very intuitive with respect to types. (It suits pretty well to glasses, thought. :)) Anyway, could we just use "UNKNOWN", which is more explicit and true reflects its nature?
Thanks, Xuefu On Fri, Oct 18, 2019 at 7:51 AM Timo Walther <twal...@apache.org> wrote: > Hi everyone, > > Stephan pointed out that our naming of a generic/blackbox/opaque type in > SQL might be not intuitive for users. As the term ANY rather describes a > "super-class of all types" which is not the case in our type system. Our > current ANY type stands for a type that is just a blackbox within SQL, > serialized by some custom serializer, that can only be modified within > UDFs. > > I also gathered feedback from a training instructor and native English > speaker (David in CC) where I received the following: > > "The way I’m thinking about this is this: there’s a concept here that > people have to become aware of, which is that Flink SQL is able to > operate generically on opaquely typed things — and folks need to be able > to connect what they see in code examples, etc. with this concept (which > they may be unaware of initially). > I feel like ANY misses the mark a little bit, but isn’t particularly > bad. I do worry that it may cause some confusion about its purpose and > power. I think OPAQUE would more clearly express what’s going on." > > Also resources like Wikipedia [1] show that this terminology is common: > > "a data type whose concrete data structure is not defined [...] its > values can only be manipulated by calling subroutines that have access > to the missing information" > > I would therefore vote for refactoring the type name because it is not > used much yet. > > Implications are: > > - a new parser keyword "OPAQUE" and changed SQL parser > > - changes for logical type root, logical type visitors, and their usages > > What do you think? > > Thanks, > > Timo > > [1] https://en.wikipedia.org/wiki/Opaque_data_type > > > -- Xuefu Zhang "In Honey We Trust!"
