Michel Cadot wrote:
> "Leigh Williams" <leighwilliams_at_gmail.com> a écrit dans le message de news: 1131807109.852054.259830_at_g44g2000cwa.googlegroups.com...
> | The logwriter writes to the logfile on disk, so it must accumulate a
> | block of log records before flushing to the log file. Suppose a
> | transaction commits, but the commit record flushing is delayed by the
> | log writer waiting to fill a block. What would happen to the
> | transaction if DBMS failure occured while waiting for its commit record
> | to be flushed? Would it simply be a case of a transaction undo in
> | recovery?
> |
>
> When a session commits it write a commit marker in the log buffer and
> signals LGWR to flush the log buffer onto disk *without* waiting the block to be filled.
> Then the session waits on the "log file sync" event till the block is on the disk.
> This leads in waste in the log block and you can see the amont of this wastage
> in the "redo wastage" statistics.
>
> Regards
> Michel Cadot
Given that Oracle has expanded COMMIT with options such as WRITE BATCH,
NOWAIT, etc. I would like to suggest that we become a bit more careful
about describing what COMMIT does and does not do. It is now version
specific and depending upon which form of COMMIT is issued.
--
Daniel A. Morgan
http://www.psoug.org
damorgan_at_x.washington.edu
(replace x with u to respond)
Received on Sat Nov 12 2005 - 15:56:18 CST
