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
<https://docs.google.com/uc?id=0BwovDucFT1fXaEREVHNWRWZyNjg&export=download&resourcekey=0-139CmIg7avLkAQJI-NUXxg>
This e-mail and any attachments may contain confidential material for the sole use of the intended recipient. If you are not the intended recipient, please 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 error, please contact the sender and delete all copies.
Thank you for your cooperation
