Fwd: Basis Question on update of Large table
Date: Sat, 20 Jan 2018 09:33:25 +0530
Message-ID: <CACzEWSUiG8b1EaxUCKUQ5bJg=R838vt=Ad+5vq4uTrc7p9W6+w_at_mail.gmail.com>
Forwarding it to correct group.
Hello Gurus,
I have a Basic question on How an update operation work on a very large
table in Oracle.
Lets say for example, my table size is 10TB, and my database buffercache
size is 10GB.
I know that the entire 10TB table cannot be brought into the Database
Buffer cache in one short as the Buffer is small, so does Oracle brings the
blocks in batches ?
Secondly lets say one batch of buffer blocks are updated and commit has not
fired, to bring the next set of buffer blocks into the buffer it has to be
pushed to the disk after the redo buffer has written the redolog files, but
if the checkpoint is not completed then the online redologs cannot be
reused right ?
Thirdly, once the database buffer blocks are pushed to disk and commit has
not happened and my undo tablespace size is lets say is 5GB, from where we
would get the read consistency of the data in case a another user fires a
select on the table ?
could you please clarify my question on the update on large table.
Sorry for asking a basic question.
I have fired an update on the 10 TB size table to update all the rows.
--
Thanks & Regards
Nilesh
Oracle DBA (sqlplus "/as sysdba" is my world)
Oracle DBA (sqlplus "/as sysdba" is my world)
"As our circle of knowledge expands, so does the circumference of darkness
surrounding it."--Einstein
"All men die, few men ever truly live" -- Braveheart
"You can get help from teachers, but you are going to have to learn a lot
by yourself, sitting alone in a room." --Dr. Seuss
"Know me for what I do and for not what I am. Judge me for what I can do
and not for what I have done."-Unknown
"Don't walk in front of me, I may not follow. Don't walk behind me, I may
not lead. Just walk beside me and be my friend."- Albert Camus
"Never argue with an idiot. They drag you down to their level and then beat
you with experience." - Unknown
--
Thanks & Regards
Nilesh
"As our circle of knowledge expands, so does the circumference of darkness
surrounding it."--Einstein
"All men die, few men ever truly live" -- Braveheart
"You can get help from teachers, but you are going to have to learn a lot
by yourself, sitting alone in a room." --Dr. Seuss
"Know me for what I do and for not what I am. Judge me for what I can do
and not for what I have done."-Unknown
"Don't walk in front of me, I may not follow. Don't walk behind me, I may
not lead. Just walk beside me and be my friend."- Albert Camus
"Never argue with an idiot. They drag you down to their level and then beat
you with experience." - Unknown
--
http://www.freelists.org/webpage/oracle-l
Received on Sat Jan 20 2018 - 05:03:25 CET