Greg Stark <gsstark@mit.edu> writes:
> All this is happening within a single transaction too, right? So there hasn't
> been an fsync the entire time. It's entirely up to the kernel when to decide
> to start writing data.
No ... there's a commit every 500 records. However, I think Chris said
he was running with fsync off; so you're right that the kernel is at
liberty to write stuff to disk when it feels like. It could be that
those outlier points are transactions that occurred in the middle of
periodic syncer-driven mass writes. Maybe fsync off is
counterproductive for this situation?
regards, tom lane