Hi Josh, Thanks for your input. There seems to be a push in the graph database world towards having a schema. It's likely something like this would be introduced in TinkerPop in the future. Let's assume that TinkerPop does support schemas, and therefore would have a type system, would this change your opinion on the matter?
Thanks again, Ken On Wed, Aug 2, 2023 at 3:54 PM Joshua Shinavier <j...@fortytwo.net> wrote: > For what it is worth, I think the question of whether null == null is only > meaningful in the context of a specific type system, which Gremlin so far > does not provide. My personal preference is to avoid SQL-style nulls and > achieve optionality through union types (e.g. Java's Optional or Haskell's > Maybe). In the case of two lists, if you can assume that the type of the > list is list<optional<int>>, then you can safely treat null like > Optional.empty(), and compare it with another null of the same logical type > (int). If that is the interpretation of your two lists, then the > intersection is [1, null]. > > Josh > > > > On Tue, Aug 1, 2023 at 5:47 PM Ken Hu <k...@bitquilltech.com.invalid> > wrote: > > > Hi All, > > > > As Gremlin evolves and gains more functionality, it is important that we > > establish some fundamental rules to provide consistency in results. One > > such question that we should come to agreement on is how null values are > > compared. Currently, Gremlin seems to mostly follow the comparison that > is > > used in Java where NULL == NULL returns TRUE. However, in many other > > database systems, NULL == NULL would return FALSE (or NULL). > > > > This question comes about as I'm starting to look a little deeper into > the > > proposed list functions. An example of where this is applicable is the > > INTERSECT list function. For example, if you have a list, A, which is > > [1,2,null] and a list, B, which is [1,null]. Should the result of an > > INTERSECT be [1,null] or [1]? > > > > I think it makes sense in Gremlin for us to follow the rule that most > > programming languages follow which is the former (NULL == NULL returns > > TRUE) because it feels more in line with how Gremlin was meant to be used > > (together with your code rather than as a string query). In this case the > > return value would be [1,null]. > > > > What are your thoughts on this subject? > > > > Thanks, > > Ken > > >
