IC65363: PERFORMANCE DEGRADATION AFTER AN INDEXED TABLE IS TRUNCATED

APAR status

• Closed as program error.

Error description

• You experience performance degradation for queries on an indexed
  table after executing the TRUNCATE TABLE command on that table.
  The performance degradation may only be detectable after
  substantial data manipulation on that table.
  
  Execute the 'onstat -C part' command. If you observe a "N" in
  the key field, your performance degradation is likely do to this
  APAR. An example output follows:
  
  B-tree Scanner Information
  
  Index Statistics
  ================
   Partnum  Key     Positions   Compress      Split  C_Level
  
  0x00100145  1 N           0          0          0      Med
  
  
  You can confirm the table and index with: 'oncheck -pT
  <database>:<table>'. Obtain the index partition partnum from the
  output, convert it to hex, and compare with the value in the
  partnum field of the 'onstat -C partn' output.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users making use of truncate table syntax in 11.50.      *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Using truncate table may inadvertently disable the btree     *
  * scanners from cleaning an index on the truncated table.      *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Upgrade to 11.50.xC7 if you are seeing performance           *
  * degradation with indices on truncated tables.                *
  ****************************************************************
  

Problem conclusion

• Problem has been fixed in 11.50.xC7.
  

Temporary fix

Comments

APAR Information

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

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

Fix information

• Fixed component name

  IBM IDS ENTRP E

• Fixed component ID

  5724L2304

Applicable component levels

• RB15 PSY

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