Method of dynamically expanding or contracting a DB2 buffer pool

Details Method of dynamically expanding or contracting a DB2 buffer pool Method of dynamically expanding or contracting a DB2 buffer pool

1992-10-27

1995-08-08

Kulik, Paul V.

Boots, shoes, and leggings

395600, 395481, 395494, 364DIG1, 3642386, 3642434, 36424341, 364245, 3642451, 36424531, G06F 1200

Patent

active

054406927

ABSTRACT:
A method of dynamically expanding or contracting a DB2 buffer pool, a set of control blocks emulating certain DB2 control blocks is constructed. If the size of the buffer pool is to be increased, the buffer pool expansion routine used by DB2 to accommodate abnormally high storage demand is repeatedly invoked to perform the expansion. However, the contractable-page flag that is set by DB2 for each 4K or 32K page that is added to the buffer pool in this way, indicating that the added page should be removed from the buffer pool as soon as the high storage demand condition has ended, is reset. If the size of the buffer pool is to be decreased, pages are removed from DB2's three queues or chains used to manage the buffer pool, i.e., the never-used chain, the previously-used chain, and the in-use chain, in that order; in the latter two cases the pages are "removed" by marking them as contractable pages so that DB2 itself will soon remove the pages from the appropriate chain as part of its own normal processing.

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Jay Ranade, Mukesh Sehgal, Phyllis Elkind & Joseph Grossman, "DB2 Concepts, Programming, and Design", McGraw-Hill, 1991, pp. 3-43, 309-313.

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