Support Article

Merge into high disk/IO and row contention

SA-31571

Summary



When merged into high disk/IO and row contention, user is seeing  sporadic high DB disk i/o, long query execution time, and row lock contention.

​This is most evident in MERGE INTO statements for the primary work table.


Error Messages



Row lock waits are high in Oracle, as well as high reads on LOB tablespaces.


Steps to Reproduce



High overall system usage.


Root Cause



A defect or configuration issue in the operating environment.  

When using Oracle secure files for blob storage with default settings one can see a large number of busy waits related to contention on the blob table.
 

Resolution

Follow the steps outlined in this document to improve performance and minimize contention:

https://pdn.pega.com/troubleshooting-high-number-busy-waits-when-using-oracle-securefiles/troubleshooting-high-number

Published December 17, 2016 - Updated January 3, 2017

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