For these reasons, a default buffer pool (called IBMDEFAULTBP) was created that supported a 4 KB page each and every time a new database was created. In addition to this, DB2 UDB always required a system temporary table space with a 4 KB page size too. Before DB2 UDB V8.2.2, the SYSCATSPACE table space was hard-coded internally such that it was always created with a 4 KB page size - a page size that you cannot change. To explain the potential benefits of doing so, it is helpful to describe how the DB2 UDB product behaves–before and after V8.2.2.īefore DB2 UDB V8.2.2, when you created a database, three separate table spaces were automatically created by default: SYSCATSPACE, TEMPSPACE1, and USERSPACE1. With the potential benefits outlined in the previous section, some database administrators (DBAs) may wonder why they would want to use a uniform page size in their databases. In addition to this, clients can choose to leverage a larger page size to support tables that exceed 64 GB in size, as an alternative to partitioning the table. Getting more data in a single unit of I/O if that data is likely related, can prove very beneficial. At the same time, workloads based on business intelligence (BI) may benefit from larger pages sizes because more data can be stored on a page that is often scanned or sorted, and so on. For example, OLTP-like applications would typically benefit from smaller pages sizes since operations tend to be small and quick-running transactions (like a new order entry into a table that tracks orders). Depending on the type of application, using a different page size can prove very beneficial. Many IBM clients like to take advantage of the flexibility in size by which the database manager can store data on disk and retrieve that data into its buffer pools. The Version 8.2.2 update of the IBM DB2 Universal Database product (DB2 UDB) includes a new capability that allows database administrators (DBAs) to use a single page size for their entire database.ĭB2 UDB supports four different page sizes: 4 KB, 8 KB, 16 KB, and 32 KB.
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