Re: expdp - cell single block physical read/ read request

Additionally, what does the initial output look like?

If there are LOBs being exported, flashback will be used by default, which will appear in the first few lines of output.

Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist Principal Consultant at Pythian
Oracle ACE Alumni
Pythian Blog http://www.pythian.com/blog/author/still/ Github: https://github.com/jkstill
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On Thu, Dec 16, 2021 at 8:35 AM Kellyn Pot'Vin-Gorman <dbakevlar_at_gmail.com> wrote:

> Another thing I’d be curious about- what does your expdp command look
> like? Are you using DOP with it?
>
> Kellyn
>
> On Thu, Dec 16, 2021 at 6:57 AM Mark W. Farnham <mwf_at_rsiz.com> wrote:
>
>> I believe you raise another valid reason which might be common. Tim
>> Gorman also mentioned small tables.
>>
>>
>>
>> (I didn’t see that after my first export failed, since I made it a habit
>> that IF I needed an export I would arrange for quiescence and single row
>> scan the table before I exported it.)
>>
>>
>>
>> I nearly always used “hot backup” for the whole database once we got to
>> 6.0.36 and sqlplus COPY for individual things, but took special care
>> pre-emptively if an export was truly required.
>>
>>
>>
>> IF you do only need part, a sqlplus COPY to the same machine was a neat
>> magic trick as far as network speed, giving you a nice clean thing to
>> export as long as you had the room.
>>
>>
>>
>> Repeat after me: “More Disk”
>>
>>
>>
>> mwf
>>
>>
>>
>> *From:* Andrew Kerber [mailto:andrew.kerber_at_gmail.com]
>> *Sent:* Thursday, December 16, 2021 9:39 AM
>> *To:* Mark W. Farnham
>> *Cc:* Jack van Zanen; ORACLE-L
>> *Subject:* Re: expdp - cell single block physical read/ read request
>>
>>
>>
>> Doesnt that mean its reading the undo tablespace for transaction
>> consistency?
>>
>>
>>
>> On Thu, Dec 16, 2021 at 8:37 AM Mark W. Farnham <mwf_at_rsiz.com> wrote:
>>
>> If memory serves this can happen with migrated rows, multi-block rows,
>> and/or multi-piece rows. Or at least some of those reasons.
>>
>>
>>
>> Oracle is going to want the contents of your row to be contiguous in your
>> export file, so it needs all the pieces. I can’t remember what happens with
>> in-line and out of line binary object columns.
>>
>>
>>
>> mwf
>>
>>
>>
>> *From:* oracle-l-bounce_at_freelists.org [mailto:
>> oracle-l-bounce_at_freelists.org] *On Behalf Of *Jack van Zanen
>> *Sent:* Wednesday, December 15, 2021 9:59 PM
>> *To:* oracle-l_at_freelists.org
>> *Subject:* expdp - cell single block physical read/ read request
>>
>>
>>
>> Hi
>>
>>
>>
>>
>>
>> Oracle 12.2.0.1 Exadata
>>
>>
>>
>> I am running a datapump and two of the workers are spending a lot of time
>> on
>> - cell single block physical read
>>
>> - cell single block read request
>>
>>
>>
>> This does not make sense to me as it is full expdp I would expected a
>> full table scan type of wait, not single block
>>
>>
>>
>> I checked mos but my search did not find anything related to my version
>>
>>
>>
>> Does anyone know of any reason why this might happen?
>>
>>
>>
>>
>>
>>
>> Jack van Zanen
>>
>>
>>
>>
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>>
>>
>> --
>>
>> Andrew W. Kerber
>>
>> 'If at first you dont succeed, dont take up skydiving.'
>>
> --
>
>
>
> *Kellyn Gorman*
> DBAKevlar Blog <http://dbakevlar.com>
> about.me/dbakevlar
>
>

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