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Reducing Buffer Pool Working Set for Certain Database Utilities

IP.com Disclosure Number: IPCOM000100250D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Haderle, DJ: AUTHOR [+3]

Abstract

This article describes a scheme to enhance a buffer management method which can improve the overall database management system throughput when the system supports on-line database utilities (i.e., database load, reorganization, recovery, image copy, build/rebuild index).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Reducing Buffer Pool Working Set for Certain Database Utilities

       This article describes a scheme to enhance a buffer
management method which can improve the overall database management
system throughput when the system supports on-line database utilities
(i.e., database load, reorganization, recovery, image copy,
build/rebuild index).

      For a database management system, data buffering is normally
used to minimize I/O activities.  The Least Recently Used (LRU)
algorithm is commonly used for buffer replacement.  However, if the
LRU buffer replacement scheme is applied to pages that are accessed
by certain database utilities, this will have an adverse effect on
the overall buffer hit ratio for other concurrent transactions.

      For example, if a single LOAD utility job is running under a
dedicated database system, the LRU scheme will use the entire
bufferpool in a round-robin fashion.  If the buffer pool is large
(say, 100,000 buffers and each buffer is 4K bytes), the buffer pool
working set will be 400 MB. For an installation which does not have
enough main memory to back the entire buffer pool, this will cause
excess of system paging activities.  Excess system paging activities
will reduce the overall system throughput as well as slowing down the
load utility job.

      In addition, the large buffer pool working set for the utility
will reduce the buffer hit ratio for other concurrent transactions.
Therefore, it is desirable to reduce the...