FAQ - Frequently Asked Questions

Yes. An identity column is a numeric column that generates a unique ID for each inserted row of a table. If you copy such a table from source to target you must consider the highest assigned value from the source table. In the case that the highest assigned value of the source is higher than the one of the target this could result in inconsistencies of DB2. Because if you copy the tablespace from source to target the highest assigned value of the target is not correct anymore. For the next INSERT into the target table DB2 would assign a duplicate value.

Since DB2 version 8 it is possible to alter the restart value of an identity column. This alteration is integrated in the automated process of BCV5|6. BCV5|6 uses the highest assigned value from the source and generates a respective ALTER statement for the target table. This statement is executed in the target, after the copy of the data is done.