If you configure the Data Integration Service to persist the lookup cache and switch the connection for the associated data object, you must update the Lookup transformation to rebuild the lookup cache based on the new connection. Otherwise, when you run the mapping, an error occurs stating that the cache file was created with a different database connection.

When you switch a connection, the Developer tool identifies the best data type match between the databases that the original connection and the new connection point to, and sets the data types accordingly. After you switch a connection, the lookup conditions might not be valid because of the data type change. You must verify the lookup conditions and manually update them.

For example, you create a mapping that contains an IBM DB2 source table, lookup table, and target table. You configure the lookup condition on an Integer column of the source table and lookup table. If you switch the connection of the lookup table from IBM DB2 to Oracle, the transformation data type of the Integer column in the lookup table changes to Decimal. The lookup condition is not valid because you cannot compare an Integer column with a Decimal column.