Re: [HACKERS] massive speedup on temp table creation/destruction?

[Merlin Moncure]

On 8/31/06, Tom Lane [EMAIL PROTECTED] wrote:

I was just trying (unsuccessfully so far) to replicate Csaba Nagy's
report of a strange failure with temp table creation.  I made use
of pgbench's recent improvements to be able to push random scripts
at a collection of backends:

$ cat ttscript.sql
create temp table foo (f1 int);
drop table foo;
$ pgbench -n -c 98 -t 1000 -f ttscript.sql bench

This is just pushing a long string of create temp table/drop table
commands at a whole lot of backends concurrently.

What I found surprising is that I get numbers like 430 tps from HEAD
and 220 tps from REL8_1_STABLE.  This test case is of course not about
performance, but I'm not quite sure what we changed that would produce
a 2X speedup from 8.1.  Can anyone else replicate this?



humm, you had me curious, so i ran the test.

postgresql. 8.2 ~ 2 weeks recent
number of clients: 98
number of transactions per client: 100
number of transactions actually processed: 9800/9800
tps = 216.424848 (including connections establishing)
tps = 217.558450 (excluding connections establishing)

8.1:
number of clients: 98
number of transactions per client: 100
number of transactions actually processed: 9800/9800
tps = 262.430496 (including connections establishing)
tps = 263.977714 (excluding connections establishing)

I did not confirm your results unfortunately. this is on quad opteron,
totally stock freshly minted database cluster :-)

I then did a cvs update on 8.2 just in case, and got:
number of clients: 98
number of transactions per client: 100
number of transactions actually processed: 9800/9800
tps = 223.026519 (including connections establishing)
tps = 224.233746 (excluding connections establishing)

note i only did a 100 transactions, so the results are expected to be
a bit more wild.

merlin

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Re: [HACKERS] massive speedup on temp table creation/destruction?

[Tom Lane]

Merlin Moncure [EMAIL PROTECTED] writes:
 On 8/31/06, Tom Lane [EMAIL PROTECTED] wrote:
 What I found surprising is that I get numbers like 430 tps from HEAD
 and 220 tps from REL8_1_STABLE.  This test case is of course not about
 performance, but I'm not quite sure what we changed that would produce
 a 2X speedup from 8.1.  Can anyone else replicate this?

 I did not confirm your results unfortunately. this is on quad opteron,

I was trying it on a dual Xeon EM64T with hyperthreading on ... I wonder
if we've unintentionally done something that optimizes for that platform?

I don't make any claim that this test case is interesting in itself,
but it might be telling us something about more-mainstream cases.

regards, tom lane

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