Re: Odd wait event freezing database

Hi Lok,

I would like to see the query text, real execution plan and ASH from all nodes for that period. I see "Cell offload" = 92.52%.I don't like to guess, but probably it causes long segment checkpoint

Best regards,
Sayan Malakshinov
Oracle performance tuning expert
Oracle Database Developer Choice Award winner Oracle ACE Associate
http://orasql.org

чт, 8 апр. 2021 г., 21:29 Lok P <loknath.73_at_gmail.com>:

> Hi All, Its version 11.2.0.4 of Oracle exadata is a 4 node RAC database.
> We are seeing one of the query runs normally finish in a few seconds but
> sometimes it runs for 3-4 minutes with the wait event being noted as
> "reliable message" and during that time period things seem to freeze in the
> database almost all the nodes getting stuck. So I am not sure if this query
> is the cause of the slowness or the victim, but it seems whenever such an
> issue occurred this query was getting executed from multiple sessions and
> was running longer than expected time. No change in plan happened for this
> query and with the same plan it used to finish in seconds during other
> times. So wanted to understand if we are hitting any bug around this wait
> event as this looks a bit unusual? It seems happening while scanning mostly
> table TSFS in FULL , want to understand what's wrong with scanning table
> TSFS?
> Below attached is the sql monitor for the same query which is showing all
> time(~200+ seconds) being spent on event "reliable message" only.
>
>
>

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