Explain EXPLAIN PIPELINE (children 3)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Function max (children 1)
      ExpressionList (children 1)
       Identifier ID
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier t1
 Identifier Null
