Logical Data Storage
Within a container, DB2 organizes data in extents, and within an extent in pages, which can be either 4, 8, 16 or 32 Kbytes in size. An extent consists of a user-specified number of pages (the default is 32). Note that before DB2 UDB Version 5.2, only 4-Kbyte pages were supported; support for 8- and 16-Kbyte pages was added in Version 5.2, and support for 32-Kbyte pages was added in Version 6.1.
A page is the lowest level of DB2 addressable data. When DB2 retrieves a row from a table on behalf of a user, the process involves reading at least one page from disk into the buffer cache in memory. When modified rows are flushed to disk by the pagecleaners, each I/O will write an entire page (a minimum of 4 Kbytes).
When data ...
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