Re: [PING] fallocate() causes btrfs to never compress postgresql files

[Thomas Munro]

Or for a completely different approach: I wonder if ftruncate() would
be more efficient on COW systems anyway.  The minimum thing we need is
for the file system to remember the new size, 'cause, erm, we don't.
All the rest is probably a waste of cycles, since they reserve real
space (or fail to) later in the checkpointer or whatever process
eventually writes the data out.