PM60732: INSERT SPACE SEARCH ENHANCEMENT, USING PREFETCH TO SCAN SPACE MAP PAGES DURING EXHAUSTIVE SEARCH

Obtain the fix for this APAR.

APAR status

• Closed as unreproducible in next release.

Error description

• INSERT performance is bad when an exhaustive search occurs, many
  getpages and SYNC IOs are made on space map pages.
  

Local fix

• Avoid frequently dataset extent by using large PRIQTY/SECQTY.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All DB2 9 for z/OS users                     *
  *                 All DB2 10 for z/OS users                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Index space map search for free page    *
  *                      during index page split takes a long    *
  *                      time for large indexes and causes       *
  *                      time-outs.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  DB2 attempts to avoid the cost of an index pageset extend by
  first searching all index space map pages for a free page
  during index page split. This exhaustive search may take a long
  time for large indexes and cause time-outs.
  
  Additional Keywords: MSGDSNT501I RC00C20255
  

Problem conclusion

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

• The index space map search algorithm has been enhanced to
  utilize page list prefetch for faster search processing. By
  reducing the amount of time needed to perform exhaustive space
  map searches, this enhancement may reduce the number of
  time-outs caused by index space map searches.
  

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UK78678 UK78679

Modules/Macros

•    DSNKSALO
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RA10 PSY UK78678

     UP12/05/26 P F205

• R910 PSY UK78679

     UP12/05/26 P F205

Fix is available

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