Shelby Cain wrote:

I'm putting 8.0 through its paces and here are a few
things I've noticed on the native win32 port running
on my workstation (2.0g p4 w/256 megs of ram).

Here is the output of "vacuum verbose item":

====================
INFO:  vacuuming "public.item"
INFO:  "item": removed 246381 row versions in 24044
pages
DETAIL:  CPU -1.-1612s/-1.99u sec elapsed 1434.79 sec.
INFO:  "item": found 246381 removable, 492935
nonremovable row versions in 50413 pages
DETAIL:  0 dead row versions cannot be removed yet.
There were 100991 unused item pointers.
0 pages are entirely empty.
CPU 1081264882.-821s/0.02u sec elapsed 1682.87 sec.

Query returned successfully with no result in 1683460
ms.
====================

As you can see the cpu statistics are obviously bogus
although the elasped time is correct.

My other concern is the length of time that vacuum
runs when cost based vacuuming is disabled.

Under 8.0, if I run an update statement (update item
where set cost = cost + 0 where country = 'US' [causes
an update w/o really changing data]) that updates half
the rows in the table (~250k out of 500k - average
tuple width is about 500 bytes) and then execute a
regular vacuum it takes approximately 1400 seconds to
complete. A vacuum full performed immediately after
takes on the order of 2000 seconds to complete.

On Windows XP with 8.0beta1 I'm experiencing different values instead, after updating 800K rows the plain vacuum takes 200 seconds and the vacuum full immediately after takes 620 seconds.

In both case the cpu usage was near zero.
I'm using a 2.2GHZ 1GB di RAM and I'm using 64MB to workmem.



Regards
Gaetano Mendola







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