Griggs, Donald wrote:
I may be confused a bit.
Regarding: 1) "the described slowdown occurs consistently on Windows
XP Home and Pro and on Windows Vista."
On its face, I would think this means that Xp Home and Vista do *NOT*
have a problem, and that "fast" behaviour represents an integrity-risk
problem.
With the caveat that at this point I am speculating on the available data...
Using two machines as an example, XP Home and XP Media Center.
XP Home and Media Center with the pragma synchronous=OFF executes the
test operation in under 2.0 seconds.
Set to FULL the times are, respectively 118 seconds and 8 seconds.
The test involves writing 1,000 rows to a table with no start/end
transaction. The resulting file is 59kb in size.
Write caching is enabled on both machines, therefore it is likely that
we can eliminate Windows caching as a factor.
At this point we have several distinct possibilities:
1. Hard drive caching. Both machines are relatively new, the Home
machine is a two year old HP Pavilion desktop replacement. The Media
Center machine is a year old HP Pavilion desktop replacement. I would
tend to think that the caching capabilities of the two machines are
close enough that 59kb of data shouldn't cause an order of magnitude
difference. I could be wrong.
2. Settings which cause Media Center to return control more
optimistically than Pro or Home. In this case, there would be a
hypothetically higher risk of data loss on the Media Center machine.
However, the point of a synchronous=FULL, as I understand it, it to
thoroughly verify that the data is "safe". It would be good to know if
there is a way to defeat this safeguard and how to determine if it has
been defeated.
3. Settings which cause Media Center to be more aggressive about
flushing its cache than Pro or Home. If this hypothesis is correct, Pro
or Home would be putting a higher priority on services other than disk I/O.
One final factor in my weighing is that performance reports I have read
on the Wiki and other postings indicate that inserts outside of a
transaction should still be closer to the single digit mark than triple
digits.
All of this having been said, all I am certain about at this time is
that XP/Vista/Pro/Home appear to be an order of magnitude slower in
returning control than Media Center and W2K. I don't know why. And
that bothers me.
John
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