"Tom Lane" <tgl@sss.pgh.pa.us> wrote
>
> The actual runtime of the "sync" program is epsilon, because it doesn't
> wait for all the I/O to happen. The entire reason for the custom is
> that the I/O is going on while you type the second "sync".
But in our 7.4.x, there is code like this:
sync();
if (IsUnderPostmaster)
sleep(2);
sync();
So for standalone backend, that's just "sync();sync()". So the "I/O is going
on while you type the second sync" theory doesn't work. For ordinary
backends, that's even more wierd - Why wasting 2 seconds is enough to save
the data? Why not 3 seconds or 4?
Regards,
Qingqing
