enq: IV - contention

From: Uwe K <uwe_at_kuechler.org>
Date: Thu, 21 Dec 2017 11:42:14 +0100
Message-ID: <f99eaad04857cea28da6ca0fea8a611d_at_kuechler.org>

Dear oracle-l'ers,

I'm interested to see whether some of you ever experienced the wait event "enq: IV - contention" being an issue on an Oracle RAC. To me, this is an exotic event and it is far from well documented. Reason: I have an open SR for five months now and no resolution to the issue yet. But before I describe the SR history in full length, i thought I'd make a short poll.

My scenario very briefly described:

  • Windows 2012R2
  • Two nodes
  • Oracle Grid Infrastructure and DB, CpuOct17 (but for a while the effect can also be seen on another system running CpuOct17)
  • Batch Job running
    • "Delete from" several tables (housekeeping)
    • gather_schema_stats( cascade=>false )
    • Index rebuild
    • All DDL run in serial
  • Application Servers shut down during batch runs (to avoid concurrency with apps)

Comparing earlier run times of this job on the 11.2 production, in 12.1 they were around twice as high.
Top wait by far is "enq: IV - contention" during the time span when gather stats and index rebuilds run.

I've already tried to confine the job to a service that runs on one instance only to avoid cluster-related waits (also top waits). That didn't change the top waits.
The only thing that helps was shutting down the other instance completely.

Any ideas?


Received on Thu Dec 21 2017 - 11:42:14 CET

Original text of this message