Explain EXPLAIN (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function count (children 1)
      ExpressionList
    TablesInSelectQuery (children 2)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Subquery (alias u1) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 2)
            Literal UInt64_1 (alias x)
            Asterisk
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier users1
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       TableIdentifier users2 (alias u2)
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier u1.uid
         Identifier u2.uid
    Function greater (children 1)
     ExpressionList (children 2)
      Function divide (children 1)
       ExpressionList (children 2)
        Literal UInt64_1
        Identifier u2.age
      Literal UInt64_1
