Re: Postgres network preformance

From: nikolaus(at)dilger(dot)cc
To: ferdinand(at)telegraafnet(dot)nl
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Postgres network preformance
Date: 2002-06-07 20:49:15
Message-ID: 20020607134916.19292.h004.c001.wm@mail.dilger.cc.criticalpath.net
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Ferdinand,

The results are not bad at all. But your test seems
flawed to me. And you would get the same result
regardles of database engine used.

You do 10,000 loops and each loop has 2 calls to the
DBI module. So if your network roundtrip is really
exactly 1ms that would put you at 20,000ms = 20 seconds
for the network roundtrips. Most likely the network
roundtrip is longer. Instead of a single ping you
would need to compare 20,000 network roundtrips without
database access.

And you should use a valid SQL statement if you want to
do a serious database test.

Regards,
Nikolaus

Ferdinand Smit wrote

>
> Hi,
>
> Does anyone have any tips to improve the network
preformance op Postgres ?
>
> To test the preformance i've done a little test using
the perlmodule DBI.
> The ping last 1 ms and the computers are identical.
>
> The test script:
>
> #!/usr/bin/perl
> use DBI;
>
> my $connectTo =
"dbi:Pg:dbname=testdb;host=obelix.telegraaf.net";
> my $dbh = DBI->connect($connectTo,undef,undef,undef)
or die("$DBI::errstr
> ($connectTo)");
> my $sth = $dbh->prepare("SELECT ?") or die
$DBI::errstr;
>
> for ($T=0; $T<10000; $T++) {
> $sth->execute($T);
> $sth->finish;
> }
> $dbh->disconnect();
>
>
> The 'time' results:
> - Running local:
> real 0m2.770s
> user 0m0.490s
> sys 0m0.250s
> - Via network:
> real 0m39.919s
> user 0m0.470s
> sys 0m0.190s
>
>
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