Re: [HACKERS] The dangers of "-F"

> >Yes.  It is not a problem that a give transaction aborts while it is
> >being done because it couldn't have been marked as completed, but the
> >previous transaction was marked as completed, and only some blocks could
> >be on the disk.
> 
> OK, this was what I suspected, and of course is the intuitively
> obvious scenario.
> 
> In other words, "-F" considered - and proven! - harmful :)
> 
> >I hope for every release.  I tried to propose some solutions, but
> >couldn't code it.
> 
> There was a bit of discussion about the cause of the problem
> in this list earlier, so part of my re-raising it was an attempt
> to encourage more discussion.  Not that I know enough about the
> code to be of any help, I'm afraid.  When I first learned of
> this problem (via my own experimentation) I dug around a bit
> and it became clear that it wasn't obvious.  I.E. the disk
> cache knows about dirty/not dirty buffers and takes great
> care to only flush dirty ones, that level of stuff.  When I
> heard that updating pg_log was apparently involved I realized
> it was more of a higher-level than lower-level problem.
> 
> Sigh...
> 
> Or am I wrong?

Writing the buffers to a file, and making sure they are on the disk are
different issues.  Also, fsync only comes into play in an OS crash, so
if that only happens once a year, and you are willing to restore from
tape in that case (or check the integrity of the data on reboot), -F
may be fine.

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