How RBA and LRSN values are displayed
Db2 12 always displays RBA and LRSN values in the 10-byte format. This 10-byte display is unrelated to migration of the catalog or directory, conversion of individual objects to EXTENDED format, or BSDS conversion. For recovery purposes, this 10-byte format is the preferred input format for Db2. When 10-byte RBA or LRSN values are specified as input to Db2, conversion to 6-byte format is performed internally as needed.
Differences between the 6-byte and 10-byte formats
The terms basic
and extended
are sometimes used to refer to the 6-byte and 10-byte
formats. When these terms are used, basic format refers to the 6-byte format, and
extended format refers to the extended 10-byte format.
- Conversion of RBA values
- A 6-byte RBA value is converted to the 10-byte format value by
adding zeros to the 4 most significant bytes. That is, the zeros are
added to the beginning of the value, as shown in the following table.
6-byte RBA value: 10-byte RBA value: 11223344556600000000112233445566 - Conversion LRSN values
- A 6-byte LRSN value is converted to a 10-byte
value by adding one zero byte to the beginning and 3 bytes added to
the end of the value, as shown in the following table.
The three bytes on the end might be might be zero or x'FF', depending on the situation. For the beginning of an LRSN range, zeros are used. For the end of an LRSN range, x'FF' is used.6-byte LRSN value: 10-byte LRSN value: 11223344556600112233445566000000
Internally, the values that are kept in memory are all 10 bytes, except when they need to be externalized to structures that remain in the 6-byte format. The conversion from the 10-byte values to 6-byte format is done at end points, such as when a log record is written, or when the PGLOGRBA field in a data or index page is updated.
Even before the BSDS is converted to Db2 11 format on all data sharing members, 10-byte LRSN values might be displayed with non-zero digits in the low order 3 bytes. LRSN values captured before the BSDS is converted continue to be displayed as they were saved until they are no longer available for display (for example, deleted by MODIFY RECOVERY). This behavior is normal and to be expected, given the many ways LRSN values are generated, stored, and handled in Db2. If these LRSN values are specified as input to Db2, specify them as shown. If the LRSN value contains non-zero digits in the low order 3 bytes, do not remove them. Any conversion that might be required takes place inside Db2.