Re: Dash_wait_chain script resulting into ORA-01489

So as you rightly said it's just not the 'DBWR' process related waits but you are seeing lot of 'log file checkpoint incomplete' and 'block change tracking waits' all over the ASH report, it may means that you are flooding the database with unexpected amount of DMLS concurrently which the database is not able to handle. You may try to see if these are all row by row DMLS spawning from multiple sessions at same time and which can be converted to bulk DML to alleviate the chatter at DB side for that interval of time.

On Sat, Mar 4, 2023 at 4:26 PM yudhi s <learnerdatabase99_at_gmail.com> wrote:

> Tried to capture the details from gv$active_session_history using Tanels
> "ash_wait_chains.sql" script during issue period from three different
> intervals i.e 5seconds, 10 seconds and 20 seconds and published in below
> link. This time the script didn't fail with the Ora-01489.
>
> https://gist.github.com/databasetech0073/3b8c9549ed9825a9888c8da1c74e60ac
>
> Most of those are pointing to DBWR process being the main blocker along
> with some 'log file switch checkpoint incomplete' and 'block change
> tracking' waita. So does it mean that the database writer is slow to catch
> up with the amount of DMLS which the application submits during this
> interval?
>
>
>
> On Sat, Mar 4, 2023 at 12:19 AM yudhi s <learnerdatabase99_at_gmail.com>
> wrote:
>
>> Thank You Pete. We are not seeing any signs of IO spike or Disk
>> utilization being saturated in the storage cells during this time. Below
>> are the database details.
>>
>> It's Oracle 19c. And Exadata machine.
>> Disk_asynch_io - True, filesystemio_options-None.
>> Platform- linux X86 64bit, CPU - 96, Cores- 48, Sockets-2.
>>
>> And also just to note , as I am unable to fetch the dash_wait_chain from
>> during the exact peak period as it is failing with error 'result
>> concatenation is too long' , so not sure if the above
>> supplied dash_wait_chain output from immediate before the issue period is
>> reliable to what extent.
>>
>>
>> On Fri, Mar 3, 2023 at 10:16 PM Peter Hitchman <pjhoraclel_at_gmail.com>
>> wrote:
>>
>>> Hi,
>>> I think some more detail about your set-up will help to get some answers:
>>> Oracle version
>>> Operating system
>>> Number of CPUs
>>> and
>>> The database I/O configuration (disk_asynch_io and filesystemio_options)
>>> and the set-up of the storage being used.
>>>
>>> I think that this points to the I/O subsystem not being able to keep up
>>> with the load it is being given.
>>>
>>> Regards
>>> Pete
>>>
>>

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