Reference Work Entry

Encyclopedia of Database Systems

pp 277-282

Buffer Management

  • Giovanni Maria SaccoAffiliated withUniversity of Torino

Definition

The database buffer is a main-memory area used to cache database pages. Database processes request pages from the buffer manager, whose responsibility is to minimize the number of secondary memory accesses by keeping needed pages in the buffer. Because typical database workloads are I/O-bound, the effectiveness of buffer management is critical for system performance.

Historical Background

Buffer management was initially introduced in the 1970s, following the results in virtual memory systems. One of the first systems to implement it was IBM System-R. The high cost of main-memory in the early days forced the use of very small buffers, and consequently moderate performance improvements.

Foundations

The buffer is a main-memory area subdivided into frames, and each frame can contain a page from a secondary storage database file. Database pages are requested from the buffer manager. If the requested page is in the buffer, it is immediately ret ...

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