On Thu, Feb 18, 2010 at 5:28 AM, Heikki Linnakangas
<heikki.linnakangas@enterprisedb.com> wrote:
> If I'm reading the patch correctly, when wal_sync_method is 'open_sync',
> walreceiver nevertheless opens the WAL file without the O_DIRECT flag.
> When it later flushes it in XLogWalRcvFlush() by issue_xlog_fsync(),
> issue_xlog_fsync() will do nothing because it assumes the write() synced
> it already. So the data written isn't being forced to disk at all.
When 'open_sync' is chosen, the WAL file is opened with O_SYNC or O_FSYNC
flag. So I think that write() flushes the data to disk even if O_DIRECT
flag is not given. Am I missing something?
> How about just forcing sync_method to 'fsync' in walreceiver?
In win32, O_DSYNC seems to be preferred to 'fsync' so far. So I'm not sure
if reshuffling of priority is harmless.
http://archives.postgresql.org/pgsql-hackers-win32/2005-03/msg00148.php
Regards,
--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center