Re: Huge DBF sequential reads by KTSJ while updating securefile LOBS.

I was reading the pre-alloc time as time spent by the space management slaves allocating space from the tablespace to the LOB segment, not time spent extending the files in the tablespace. But that might be a simultaneous issue. I think the information you get from the ASH data might help identify that - the blocks might be the start of file blocks, or near the start of LOB segment blocks - or possibly near the start of newer extents in the LOB segment blocks.

Regards
Jonathan Lewis

On Fri, 1 Apr 2022 at 02:29, Goti <aryan.goti_at_gmail.com> wrote:

> Thanks Jonathan for the details.
>
> I will check ASH for further details. Additionally , I did try to add more
> space to the respective LOB table space and we do have enough free space
> now. But one thing I am not getting like why SMCO still need to watch out
> for extending the space ?
>
> On Thu, 31 Mar 2022 at 10:31 PM, Jonathan Lewis <jlewisoracle_at_gmail.com>
> wrote:
>
>>
>> It's not your version, of course, but I was looking at a similar issue on
>> 19c a little while ago:
>> https://jonathanlewis.wordpress.com/2022/01/10/control-file-waits/
>>
>> Some work of this type has to be done by some process - it's just a
>> question of how visible it becomes to end-user run-time
>>
>> Regards
>> Jonathan Lewis
>>
>>
>> On Thu, 31 Mar 2022 at 12:35, Goti <aryan.goti_at_gmail.com> wrote:
>>
>>> Hi All,
>>>
>>> Envt :11.2.0.4 on RHEL 6.5
>>>
>>> We are observing slowness in OGG replication on the target side. The
>>> replication itself is updating a table which has a secure file LOB. There
>>> are a lot of updates performed during this time (Close to 25K in an hour).
>>> The FG session waits for "direct path write" as it was created with the
>>> NOCACHE attribute. However, the ASH shows that this is internally
>>> triggering some space management slaves to do many single block reads.
>>> There are no trace files also associated with the W00* processes.
>>>
>>> Please find the TKPROF report for the OGG replicat OS process.
>>> https://gist.github.com/aryangoti/f49660a4bbb23c58a9f403ac9270eb7a
>>>
>>> Snapper for W0003 process.
>>> https://gist.github.com/aryangoti/f2cf46ebcec3920d79f4fb719c01f309
>>>
>>> ASH details (5 minutes) when the replication was slow.
>>> https://gist.github.com/aryangoti/6674691d7770b6eb667718589633aec5
>>>
>>> Please let me know how to troubleshoot this further.,
>>>
>>> Thanks,
>>>
>>> Goti
>>>
>> --
> Thanks,
>
> Goti
>

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