Explain EXPLAIN ESTIMATE (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function any (children 1)
      ExpressionList (children 1)
       Identifier s
    TablesInSelectQuery (children 2)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Subquery (alias t1) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 1)
           ExpressionList (children 1)
            Literal \'\' (alias s)
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias t2) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 1)
            Literal \'\' (alias s)
           ExpressionList (children 1)
            Function connection_id (children 1)
             ExpressionList
      TableJoin (children 1)
       ExpressionList (children 1)
        Identifier s
