SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier merge_tree
   Function equals (children 1)
    ExpressionList (children 2)
     Function toUInt32 (children 1)
      ExpressionList (children 1)
       Identifier x
     Literal UInt64_0