Architecture

Let's start by reviewing the significant changes to the architecture of DB2 and related requirements. One of the biggest impacts of V8 will be the requirement to be running a zSeries machine and z/OS v1.3 ”DB2 V8 will not support old hardware nor will it support OS/390. Additionally, DB2 customers must migrate to V7 before converting to V8. There will be no IBM-supported capability to jump from V6 (or an older version) directly to V8 without first migrating to V7.

Owing to these architectural requirements, DB2 will have the ability to support large virtual memory. This next version of DB2 will be able to surmount the limitation of 2GB real storage that was imposed due to S/390's 31-bit addressing. Theoretically, with 64-bit addressing DB2 could have up to 16 exabytes of virtual storage addressability to be used by a single DB2 address space. Now there is some room for growth!

Broader usage of Unicode is another architectural highlight of DB2 V8. V7 delivered support for Unicode-encoded data, but V8 forces its use. If you do not use Unicode today, you will when you move to V8. This is so because many of the table spaces in the DB2 system catalog will be implemented using Unicode. In fact, the DB2 catalog has some other dramatic changes coming under V8 ”including some table spaces with larger page sizes and long names .

Actually, support of long DB2 object names is another significant architectural change in V8. DB2 V8 significantly increases the maximum length of most DB2 object names. For example, instead of being limited to 18 byte table names, you will be able to use up to 128 bytes to name your DB2 tables; the same limit applies to most DB2 objects and special registers including views, aliases, indexes, collections, schemas, triggers, and distinct types. The limit for columns is 30 bytes, a table space is still 8 bytes, and packages are still 8 bytes, unless it is a trigger package, which can be 128 bytes. This brings a lot of flexibility, but also a lot of reworking of the DB2 catalog tables.

One such reworking requires the use of table spaces with 8K, 16K, and 32K page sizes. Therefore, the system catalog in DB2 V8 will require use of the BP8K0 , BP16K0 , and BP32K buffer pools.