create_snapshot

create_snapshot 
      ::= 
      "create  " "snapshot  " [ schema_name ". " ] snapshot_name 
      { storage_parameter } 
      [ "cluster" cluster_name "(" column_list ")" ] 
      [ "refresh" [ "fast" | "complete" | "force" ] 
      [ "start" "with" date ] 
      [ "next" date ] ] 
      [ "as" query ] 

[rule list]
This rule is call by

create_command