If you never come close to filling the LOG_BUFFER before a flush event, then
the downside is occupying memory you never use.
I have *not observed* Oracle performance degrade due to having a large
LOG_BUFFER if there is no essential better use for the memory such as
caching large frequently referenced look up tables.
I usually safely oversize the LOG_BUFFER so that hitting the buffer
one-third full is not routinely the flushing event, but I've never needed as
much as you are currently using.
Once your LOG_BUFFER is big enough so you cannot write one-third of it
before the time triggered flush, I *believe* that constitutes a useful upper
size limit, even if your jobs are all single commit monoliths. (There may be
other useful upper size limits that are smaller, ergo the use of "a" not
"the" in the phrase "a useful upper size limit.")
*Someone let me know if that is not still at least theoretically correct.*
So while you *might* be "wasting" some memory, I'm not aware of any other
harm. I don't believe they will let you set it bigger than the program can
handle.
mwf
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Chitale, Hemant K
Sent: Wednesday, May 18, 2016 2:02 AM
To: ram.cheruvattath@xxxxxxxxx; oracle-l-freelists
Subject: RE: LOG_BUFFER
What kind of storage do you write to @4TB/hour ? How and when do you backup
and purge/delete the archivelogs.
I've seen log buffer exceeding 1GB.
Hemant K Chitale
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Ram Cheruvattath
Sent: Wednesday, May 18, 2016 3:00 AM
To: oracle-l-freelists
Subject: LOG_BUFFER
Hi
We have a 12c database that has very high redo generation (4TB/hr). Our
log_buffer is set to 1GB.
Is there a downside to setting log_bugger this big?
Thanks
Ram
This email and any attachments are confidential and may also be privileged.
If you are not the intended recipient, please delete all copies and notify
the sender immediately. You may wish to refer to the incorporation details
of Standard Chartered PLC, Standard Chartered Bank and their subsidiaries at
https://www.sc.com/en/incorporation-details.html
