fche(at)redhat(dot)com (Frank Ch. Eigler) writes:
> Could you explain how postgresql can "fall victim" the filesystem hole
> mechanism? Just hoping to force actual storage allocation, or hoping
> to discourage fragmentation?
The former. We'd prefer not to get an unexpected "disk full" failure
while writing to a log file we thought was good.
To the extent that prewriting the WAL segment discourages fragmentation,
that's good too, but it's just a side benefit.
regards, tom lane