Working with user-defined fields

In addition to system fields available by default in various Alloy Navigator tables, you can add new fields. These fields are called user-defined fields, or UDFs. They are displayed in the Alloy Navigator Desktop App and in the Alloy Navigator Web App.

See the following sections for instructions:

Total Size Limit

Microsoft SQL Server 2005 has a row size limitation and so the total size of all object’s fields (both standard and user-defined) cannot exceed the predefined limit of 8 KB. For details, see https://blogs.msdn.microsoft.com/msdnts/2006/12/01/row-size-limitation-in-sql-2000-and-2005/

In Microsoft SQL Server 2008, this restriction is relaxed, but creating rows larger than 8 KB might affect performance because SQL Server still maintains a limit of 8 KB per page. For details, see https://docs.microsoft.com/en-us/previous-versions/sql/sql-server-2008-r2/ms186981(v=sql.105).

That’s why we recommend that you pay attention when adding UDFs, especially of the String type, which are longer than the others. If the combined size of all fields exceeds the limit, you will receive a warning message advising you to reduce the size of the field you are adding or reduce the combined size of all UDFs. If you ignore the advice, a data loss will occur.

NOTE: Memo fields have a special structure and don't count against the 8KB limit. Strictly speaking, they do occupy 4 bytes in the record as a reference to the data chunk stored in an external file.