On 3/1/07, Pavan Deolasee <[EMAIL PROTECTED]> wrote:

Hi All,

Here are some preliminary numbers with the HOT 4.0 patch that I sent
out earlier today. These are only indicative results and should not be
used to judge the performance  of HOT in general. I have intentionally
used the setup favorable to HOT. The goal here is to point out the best
usage of HOT so that we get some early feedback about its usefulness.
We still need to run several benchmark tests to see where it would
be useful and where it would add unnecessary overhead without any
real gains. This would also require lot of tuning and would be heavily
dependent on the community feedback/suggestions.

I tested HOT patch (currently 3.2) over a wide variety pf pgbench runs
and found there to significant improvements (5-40%) in most cases.
Generally, I ran fsync=off and stock fillfactor.  I'm also a huge
believer in HOT once all the kinks get worked out.  I had some wierd
glitches in earlier versions of the patch which I could not quite
figure out and may have been some problems on my end...the new version
seems pretty solid except for one possible problem...at one point when
I dropped then later added the index on 'abalance', I got spammed
'WARNING:  found a HOT-updated tuple' from psql prompt.

I was also curious about the 'worst case' of HOT so I added an index
on abalance and did some runs.   The runs are not quite long enough to
remove all volatility from the results but they should be close:

**** index on abalance ****
[EMAIL PROTECTED] ~]# pgbench -c1 -t100000 -p 5000 [HOT]
tps = 448.104436 (excluding connections establishing)

[EMAIL PROTECTED] ~]# pgbench -c1 -t100000
tps = 448.120719 (excluding connections establishing)

[EMAIL PROTECTED] ~]# pgbench -c10 -t10000 -p 5000 [HOT]
tps = 363.444429 (excluding connections establishing) run #1
tps = 415.854569 (excluding connections establishing) run #2

[EMAIL PROTECTED] ~]# pgbench -c10 -t10000
tps = 416.659906 (excluding connections establishing)

**** no index on abalance ****
[EMAIL PROTECTED] ~]# pgbench -c10 -t10000 -p 5000 [HOT]
tps = 659.870628 (excluding connections establishing)

[EMAIL PROTECTED] ~]# pgbench -c10 -t10000
tps = 321.889840 (excluding connections establishing)

platform is intel pentium D 3ghz, 2xsata 7200rpm software raid0,
redhat fc4.  This is my dev box which I usually run fsync=off to get
comparable performance with production systems and caching raid


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