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@xxxxxxxxx] ;
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@xxxxxxxx> 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@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Jack van Zanen
Sent: Wednesday, December 15, 2021 9:59 PM
To: oracle-l@xxxxxxxxxxxxx
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
<https://docs.google.com/uc?id=0BwovDucFT1fXaEREVHNWRWZyNjg&export=download&resourcekey=0-139CmIg7avLkAQJI-NUXxg>
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