Explain EXPLAIN QUERY TREE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function sum (children 1)
      ExpressionList (children 1)
       Function minus (alias i) (children 1)
        ExpressionList (children 2)
         Identifier uint64
         Literal UInt64_1
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier test_table
    Function greater (children 1)
     ExpressionList (children 2)
      Identifier i
      Literal UInt64_0
