Guidelines for Modifying a Predefined One-to-One Extension Table

It is strongly recommended that you add custom extension columns to the base table to store your data instead of storing frequently accessed data in columns in a one-to-one extension column. It is strongly recommended that you do not modify a predefined one-to-one extension table or the column of a predefined one-to-one extension table for the following reasons:

• Some of the columns that reside in a predefined extension table are not available to use because Siebel CRM uses them. You must not modify or delete an extension column that Siebel CRM uses.

• A C++ class might use the extension table in a reserved way. Modifying this table might cause behavior that you cannot predict.

• An upgrade effort might use the extension table, so you cannot predict future use of this table.

• Docking rules use some extension columns, so these columns are reserved for use with Siebel Remote. For more information, see Configuring Dock Objects for Siebel Remote.

• Use of an extension table affects performance because Siebel CRM must include the table in all queries that use the field that Siebel CRM uses to run the query. This situation can become a problem if Siebel CRM joins the table to multiple business components, specifically if a number of extension tables are in use.

It is permissible to use a predefined one-to-one extension table in the following situations:

• If you must use a LONG column because the database permits only one LONG column for each database table.

• If the implementation of a database constraint is beneficial. For example, to realize the improved performance that results when maximum bytes in a row are used before record chaining occurs.