Switching off the redo log writing has no influence an flushing the data
cache.
The
amount of changes and your data cache size are the parameters which influence
triggering savepoints (data flush to device).
regards
uwe
-----Original Message-----
From: Dmitri Lyssenko [mailto:[EMAIL PROTECTED]
Sent: Freitag, 28. M�rz 2003 10:17
To: [EMAIL PROTECTED]
Subject: Log Writer off + O_DIRECT - synchronous write on each commit?Hi all,
Unfortunately the documentation is not clear about these options.
It appeared from the test that if the log writer is disabled (that I believed give me the
best performance) the database starts flushing the data cache very often...probably
on each commit. This guess is originated from the look at the "vmstat" output
(however I might be wrong). As result having these 2 options together (SET LOG
WRITER OFF and USE_O_DIRECT YES) gave me the worst performance.
Is it right that the frequencity of the savepoints depends on the state of the log writer
(disabled/enabled)...and therefore O_DIRECT should not be used with the log
switched off?
Thanks in advance,
Dmitri Lyssenko,
Nuix Pty. Ltd.
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