Greg Smith wrote:
> Tom Lane wrote:
> > You've got entirely too simplistic a view of what the "delta" might be,
> > I fear. In particular there are various sorts of changes that involve
> > inserting the data carried in the WAL record and shifting pre-existing
> > data around to make room, or removing an item and moving remaining data
> > around. If you try to replay that type of action against a torn page,
> > you'll get corrupted results.
> >
>
> I wasn't sure exactly how those were encoded, thanks for the
> clarification. Given that, it seems to me there are only two situations
> where full_page_writes is safe to turn off:
>
> 1) The operating system block size is exactly the same database block
> size, and all writes are guaranteed to be atomic to that block size.
Is that true? I have no idea. I thought everything was done at the
512-byte block level.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
