Merge into high disk/IO and row contention
SummaryWhen 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 MessagesRow lock waits are high in Oracle, as well as high reads on LOB tablespaces.
Steps to ReproduceHigh overall system usage.
Root CauseA 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.
Follow the steps outlined in this document to improve performance and minimize contention:
Published December 17, 2016 - Updated January 3, 2017