Happens at the time of database scan
Sai Kiran, November 29, 2018 - 5:02 pm UTC
Thank you so much for your response. The issue starts happening only during the time when the jobs starts to run and not for rest of the day.
Also what are the bugs in this process??
That said, there are a couple of bugs relating to dbms_stats & library cache locks.
Is this applicable only for 11g ?
November 29, 2018 - 5:22 pm UTC
For example: "Bug 19790972 "library cache lock" waits due to DBMS_STATS gather of stats for a subpartition"
But I don't know enough about your situation to be sure that's the cause. It could be something else! If you've definitely narrowed the problem down to stats gathering, you need to contact support.
Interested in Bug information
A reader, March 27, 2020 - 5:02 pm UTC
Hi Chris,
That said, there are a couple of bugs relating to dbms_stats & library cache locks. In particular if you have partitioned tables.
Could you please share bug information which you are pointing above.
I am getting library cache lock event for SQL ID "dbms_stats.gather_database_stats_job_proc ( )" in AWR and at the same time other SQL's running slow.
March 30, 2020 - 12:04 am UTC
You should check with Support, because you would want to make sure observations you are making are related or not to the bugs below:
Bug 7292916 - Improved row cache callbacks / Slow DBMS_STATS
Bug 19790972 - "library cache lock" waits due to DBMS_STATS gather of stats for a subpartition
Bug 20754583 - 'library cache: mutex x' in different instances where dbms_stats was executed
Bug 6011045 - DBMS_STATS causes deadlock between 'cursor: pin S wait on X' and 'library cache lock'