Re: Changing the default wal_sync_method to open_sync for Win32?

["Merlin Moncure" <merlin(dot)moncure(at)rcsonline(dot)com>]

> Magnus Hagander wrote:
> > I'd like to see this one also considered for 8.0.x, though I'd
certainly
> > like to see some more testing as well. Perhaps it's suitable for the
> > "8.0.x with extended testing" that is planned for the ARC
replacement
> > code?
> >
> > It does make a huge difference on win32. While we definitly don't
want
> > to risk data, a 60% speedup in write intensive apps is a *lot*.
> 
> While this patch has been applied to CVS HEAD, there are still two
open
> issues:
> 
> 1.  Should it be the default wal_sync_method for Win32?

I vote no.  Even though the performance of fsync sucks, it is safe, and
the stock config on most win32 systems is to cache writes.  I suspect
that while write caching on/O_SYNC might be a little safer that fsync
due to a shorter cache degradation period, it's not good enough.


> 2.  Another question is what to do with 8.0.X?  Do we backpatch this
for
> Win32 performance?  Can we test it enough to know it will work well?
> 8.0.2 is going to have a more rigorous testing cycle because of the
> buffer manager changes.

I vote to backport.  Without O_SYNC, it is impossible to get reasonable
performance out of a caching raid controller in many configurations.

Merlin