Tuning Subsystems › Buffer Pools › Sequential Versus Random Processing

Sequential Versus Random Processing

VPSEQT is the percentage of the virtual buffer pool that can be used for sequentially accessed pages. This percentage prevents sequential data from using all the buffer pool and to keep some space available for random processing. You can set this value from 0 to 100 percent with the default being 80 percent, which indicates that 80 percent of the buffer pool is to be set aside for sequential processing and 20 percent for random processing. Set this parameter according to how your objects in that buffer pool are processed.

One tuning option that is used is altering the VPSEQT to 0 percent to set up the pool for random use only. When VPSEQT is set at 0 percent, the SLRU will no longer be valid and the buffer pool is now random. Because only the LRU used, all pages on the SLRU have to be freed. This setting also disables prefetch operations in this buffer pool, which is beneficial for certain strategies.