Hi Zihan, I support the first solution, though “select ** from root” may be strange : )
Besides, I’d like to append another case: I looked up the usage of wildstar in Linux : /tmp/* matches any file in /tmp. // Substitutes for any number of characters, except /. /tmp/** matches all files and directories underneath /tmp. // Substitutes for any number of characters, including /. So we should also consider that ** also contains zero layer. For example, if we have some storage groups: root.a.sg1 root.a.b.sg2 root.b.sg3 For "delete storage group root.a", we do not delete any sg. For "delete storage group root.a.*" we delete root.a.sg1 For "delete storage group root.a.sg1.*" we do not delete any sg. For "delete storage group root.a.**" we delete root.a.sg1, root.a.b.sg2 If we also have another storage group “root.a”: For "delete storage group root.a", we delete root.a For "delete storage group root.a.*" we delete root.a.sg1 (because * does not include zero layer) For "delete storage group root.a.**" we delete root.a, root.a.sg1, root.a.b.sg2 (because ** includes zero layer) Best, ----------------------------------- Zesong Sun School of Software, Tsinghua University 孙泽嵩 清华大学 软件学院 > 2021年3月4日 11:13，weizihan0110 <[email protected]> 写道： > > Hi all: > The initial discussion is at https://issues.apache.org/jira/browse/IOTDB-1160) > > First Solution: > > "*" matches just one layer and "**" matches one or more layers. As a result, > the SQL statement "select * from root" have to be converted into "select ** > from root". It seems a little bit disappointing. > > Second Solution: > "*" matches one or more layers by default. And we can put something like "1 > layer"(layer is the keyword) in the SQL statement to strengthen the semantics > to match just one layer. More, "2 layers" to match just two layers and so on. > This solution can be more scalable, I think. > > > Does anyone have any idea about this? Welcome to discuss.
