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

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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