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From: Jonathan Lewis <jlewisoracle@gmail.com>
Date: Thu, 16 Dec 2021 08:22:20 +0000
Message-ID: <CAGtsp8mOWoVq8hoE-KfwwXT+v-sFDcUqwpDujFt2aq18cKbWLg@mail.gmail.com>
Subject: Re: expdp - cell single block physical read/ read request
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Do you have any indication that you're dealing with chained rows?  expdp
would have to follow chained rows across blocks, doing single block reads.
I'm not sure if your version would do the same with migrated rows, but it
might if it follows the code path used by parallel tablescans.

Regards
Jonathan Lewis


On Thu, 16 Dec 2021 at 03:02, Jack van Zanen <jack@vanzanen.com> wrote:

> 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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<div dir=3D"ltr"><div><br></div><div>Do you have any indication that you=
9;re dealing with chained rows?=C2=A0 expdp would have to follow chained ro=
ws across blocks, doing single block reads.</div><div>I&#39;m not sure if y=
our version would do the same with migrated rows, but it might if it follow=
s the code path used by parallel tablescans.</div><div><br></div><div>Regar=
ds</div><div>Jonathan Lewis</div><div><br></div><div><br></div><div><br></d=
iv></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmail_att=
r">On Thu, 16 Dec 2021 at 03:02, Jack van Zanen &lt;<a href=3D"mailto:jack@=
vanzanen.com">jack@vanzanen.com</a>&gt; wrote:<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex"><div dir=3D"ltr">Hi<div><br></div><div><br=
></div><div>Oracle 12.2.0.1 Exadata</div><div><br></div><div>I am running a=
 datapump and two of the workers are spending a lot of time on=C2=A0<br>- c=
ell single block physical read</div><div>- cell single block read request</=
div><div><br></div><div>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</div><div=
><br></div><div>I checked mos but my search did not find anything related t=
o my version</div><div><br></div><div>Does anyone know of any reason why th=
is might happen?</div><div><br></div><div><br></div><div><br clear=3D"all">=
<div><div dir=3D"ltr"><div dir=3D"ltr"><div>Jack van Zanen</div><div><br></=
div><div><img width=3D"96" height=3D"96"><br>------------------------- <br>=
This e-mail and any attachments may contain confidential material for the s=
ole use of the intended recipient. If you are not the intended recipient, p=
lease be aware that any disclosure, copying, distribution or use of this e-=
mail or any attachment is prohibited. If you have received this e-mail in e=
rror, please contact the sender and delete all copies.<br>Thank you for you=
r cooperation </div></div></div></div></div></div>
</blockquote></div>

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