PK76544: INSERT INTO A VARCHAR COLUMN IN A PARTITIONED TABLESPACE PERFORMS POORLY

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Extended elapsed time during INSERT into a VARCHAR column in a
  Partitioned tablespace space was seen with data length of 10800
  as the space search for the INSERT begins to sequentially read
  many spacemap pages and perform poorly.
  At 16200 characters long, the problem was not seen, as the space
  search for the INSERT directly reads only the needed second
  spacemap page, then the first and then INSERTs finally in the
  page it needs.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of DB2 for zOS non-segmented table     *
  *                 space                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: 1. Extended elapsed time increase during*
  *                         INSERT into a VARCHAR column in a    *
  *                         Partitioned table space.             *
  *                      2. Table space is growing when there    *
  *                         are many zero pages between          *
  *                         space map pages.                     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  1. When the remaining space on the data page is enough for the
     minimum size record but not enough for larger size record,
     the current space search algorithm tries to search every
     target page without any limitation. This space search caused
     a large amount of get pages and slowed down the insert
     performance.
  
  2. During the space search, a new space map page is formatted
     before all of the data pages within the last space map page
     are used. This causes the growing of the table space.
  

Problem conclusion

• 1. Modified space search algorithm during exhaustive  search
     without extend to give up the current search algorithm after
     3 visits to data pages and fail finding space for insert.
  
  2. Modified space search algorithm to ensure data pages are
     used before formatting another space map page. This is to
     prevent unnecessary growing of table space.
  

Temporary fix

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

Comments

• ž**** PE09/04/28 FIX IN ERROR. SEE APAR PK85539  FOR DESCRIPTION
  

APAR Information

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

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

  UK45207 UK45208

Modules/Macros

• DSNDINPL DSNISMEX DSNISMPI DSNISMRS DSNISMRT
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• R810 PSY UK45207

     UP09/04/13 P F904

• R910 PSY UK45208

     UP09/04/13 P F904

Fix is available

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