Unless it is necessary, applications should not request long data (SQL_LONGVARCHAR and SQL_LONGVARBINARY data), because retrieving long data across a network is slow and resource-intensive.
Most users do not want to see long data. If the user does need to see these result items, the application can query the database again, specifying only the long columns in the select list. This method allows the average user to retrieve result sets without having to pay a high performance penalty for network traffic.
Although the best method is to exclude long data from the select list, some applications do not formulate the select list before sending the query to the ODBC driver (for example, some applications SELECT * FROM table_name ...). If the select list contains long data, the driver must retrieve that data at fetch time, even if the application does not bind the long data in the result set. When possible, use a method that does not retrieve all columns of the table.
