IBM Db2 11.1 Certification Guide

Buffer pool planning

Have you ever wondered which is better, one large buffer pool or many small ones? The answer depends on the data design and the transactional workloads that have been defined. As a general rule, one large buffer pool will perform better than several small ones. Db2 supports 4K, 8K, 16K, and 32K buffer pool page sizes. As a rule, a row cannot span a page, since page chaining can significantly degrade performance. To prevent this, a new DB CFG parameter was added in v10.5, named EXTENDED_ROW_SZ. When enabled, this setting will allow a row to span a page, creating chained pages. For example, it will allow a row larger than 4,005 to be stored in a 4,096 page size.

We recommend disabling DB CFG EXTENDED_ROW_SZ, unless it is ...