Using DB2 Universal Database on 64-bit Platforms

Chapter 1. Why 64-bit Support?

The advent of 64-bit computing platforms presents new possibilities for increased performance of database servers as well as database applications. 32-bit platforms have an inherent address space limitation of 4 gigabytes (GB) for the kernel plus user text and data. Removal of this 4 GB limit on the address space of database servers allows for the creation of larger buffer pools, sort heap, package caches, and other resources that can consume large amounts of memory. This, in turn, leads to much improved performance, especially for sort and input/output (I/O) operations.

Other 32-bit limitations and problems can be removed by using a 64-bit implementation. For example, on AIX, there are approximately ten memory segments available for use in mmap or shmat calls. This directly limits the number of local database connections that a DB2 application can have, because one shared memory segment is required for each local connection. As well as eliminating restrictions on the amount of memory available both on the stack and the heap of an AIX executable, a 64-bit implementation is not subject to potential stack heap collisions.

The availability of both hardware and operating systems capable of using greater than 4 GB of memory means that a 4 GB barrier is a significant limitation to memory-intensive applications and the larger middleware vendors who require large database installations.

Some application developers are also migrating their applications to 64-bit platforms. 64-bit applications are able to access files that are greater than 2 GB in size. To achieve this level of access with 32-bit applications requires special code or build modifications. For 64-bit applications to work with DB2 family databases, they must have access to 64-bit versions of the DB2 application libraries. Although 64-bit platforms allow both 32-bit and 64-bit processes to coexist, they do not allow intermixing of 32-bit and 64-bit executables and libraries within the same process.

To exploit this increased memory address space, IBM has developed a 64-bit version of the DB2 Universal Database (UDB) and DB2 Connect servers for 64-bit platforms. Application libraries that enable access to DB2 family databases from 64-bit applications are now available.

Client/server configurations supported in this release are:


[ Top of Page | Previous Page | Next Page ]