Re: nested structs. querying and building metadata in calcite

[Vladimir Sitnikov]

Stamatis>They're already supported by the SQL parser and the relational
algebra and
Stamatis>soon (<https://issues.apache.org/jira/browse/CALCITE-2404>) they
will be
Stamatis>supported also by the execution engine in the enumerable
convention.

Does it require struct type to be fully qualified upfront?

For instance, can it support tree-like structures like the following?

Node {
  Node left;
  Node right;
};

or something like

Node {
  Object left; // it can be Node or other type
  Object right;
};

Vladimir