Explain EXPLAIN (children 2)
 Set
 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 t (alias n)
    Function and (children 1)
     ExpressionList (children 2)
      Function exists (children 1)
       ExpressionList (children 1)
        Subquery (children 1)
         SelectWithUnionQuery (children 1)
          ExpressionList (children 1)
           SelectQuery (children 3)
            ExpressionList (children 1)
             Asterisk
            TablesInSelectQuery (children 1)
             TablesInSelectQueryElement (children 1)
              TableExpression (children 1)
               Function numbers (children 1)
                ExpressionList (children 1)
                 Literal UInt64_10
            Function notEquals (children 1)
             ExpressionList (children 2)
              Identifier number
              Identifier n.x
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier n.y
        Literal UInt64_1
