Browse Prior Art Database

Control of DBMS Working Set Size

IP.com Disclosure Number: IPCOM000121449D
Original Publication Date: 1991-Sep-01
Included in the Prior Art Database: 2005-Apr-03
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Fecteau, G: AUTHOR [+3]

Abstract

Disclosed is a method for SQL/DS* to combine its information with the information available from the operating system (VM/ESA*) in order to improve overall system performance.

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

Control of DBMS Working Set Size

      Disclosed is a method for SQL/DS* to combine its
information with the information available from the operating system
(VM/ESA*) in order to improve overall system performance.

      The implementation will allow SQL/DS some control on the amount
of memory it uses. It also will allow SQL/DS to inform VM/ESA about
storage reference patterns from each of its concurrent user requests.
This is done using the following VM/ESA interfaces:
      -  INDICATE USER command
      -  DIAGNOSE X'10'
      -  REFPAGE macro

      The output from the VM/ESA CP command 'INDICATE USER' is used
to find out the consumption of real storage by SQL/DS. This output is
compared to the operator-defined target storage size. The result of
the comparison is used in conjunction with the storage residency
priority to locate pages that are candidates for release. The release
is performed using the DIAGNOSE X'10' interface. Since contents of a
released page are lost, DIAG X'10' is not issued for pages that have
been modified but not saved on DASD.

      SQL/DS releases real storage for pages under the following
circumstances:
    -  For work areas, as soon as the information in the work area is
no longer required, the entire area is released.
    -  Real storage for pages containing user data may be released
after the page contents are moved to a local buffer. The decision on
whether or not a page is to be released is made on the basis of
the working storage residency priority scheme that the Data Base
Administrato...