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Investigating EBS Row Lock Contention

Avatar photoCustomer Questions & Answers 5 replies

We have users frequently stuck waiting on ‘enq: TX – row lock contention’. We need a real-time view of the blocking chain to find the root cause, especially when the blocking session goes idle. Which report should I use?

5 replies

  • Support Enginatics

    You should primarily use the DBA Blocking Sessions report, which shows the chain of currently blocking and blocked database sessions derived from `v$wait_chains`. This gives you the current lock scenario.

  • Avatar photoCustomer

    What about using ASH data, or sessions that might not appear in real-time views if they quickly go idle?

  • Support Enginatics

    For analysis involving the Active Session History (ASH), utilize the DBA SGA Blocking Session Summary. While row lock scenarios sometimes involve idle blocking sessions not visible in ASH, this summary helps correlate active blocking events. You can perform further analysis using a pivot in Excel for faster root cause identification.

  • Avatar photoCustomer

    If I suspect the blocking is caused by an uncommitted update, which AWR metric would reflect that wait time?

  • Support Enginatics

    The DBA AWR SQL Performance Summary report provides visibility into ‘Application Wait Time’, which captures total elapsed time in seconds from the wait event class ‘Application’, such as ‘enq: TX – row lock contention’ caused by an uncommitted session’s update blocking another session.

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