Re: Vacuum related question

"G. Thomas Yagel, Jr." <tyagel(at)yahoo(dot)com> writes:
> After 12 hours I stopped inserting recods and started a "vacuum verbose".
> The vacuuming has taken almost 2 hours now and is not even finished. What I
> don't understand is why there is so much vacuuming to be done on some tables
> that are only being inserted into. As an example, I have pasted the output
> from the vacuuming of the pg_largeobject table.

You may think you've only inserted, but this output says differently:

> INFO: "pg_largeobject": found 18317486 removable, 21326336 nonremovable row
> versions in 2119638 pages

Those 18 million dead rows didn't appear out of nowhere; they could only
have come from deleting or updating large objects (BLOBs).

The reason for the multiple index-cleaning cycles is that vacuum_mem was
only high enough to remember about 1.4 million dead rows at a time.
You could have sped up the process by setting vacuum_mem higher.

regards, tom lane