> In the brave new world of WAL, Postgres does not flush dirty buffers
to
> disk at transaction commit, relying on WAL to clean up if a database
or
> system failure occurs. If we don't log page images to WAL then I
think
> there's a hole here wherein a Postgres crash can lose data even though
> no failure of the surrounding OS occurs. Maybe it's safe, but I'm not
> convinced.
It should be (imho *is*) safe for heap pages, but not for index pages.
The reasoning for heap pages is, that the WAL code (pre page image)
already
coped with future heap page versions.
I would not expect it to work for index pages, since one "feature" of
the page images was to "undo" future index operations.
Andreas
