Re: High CPU load on Postgres Server during Peak times!!!!

Hello Craig,

Are you sure this is correct?

The test program (see below) with autocommit=0 counts up when an insert is
done in
another session and there is no commit done.

I think with each new select a new implicit transaction is done when no
explicit "BEGIN" has been established.

Can one confirm this behavior?

Thnx.

Ciao,
Gerhard

# Disable autocommit!
my $dbh = DBI->connect($con, $dbuser, $dbpass, {RaiseError => 1,
AutoCommit=>0}) || die "Unable to access Database '$dbname' on host
'$dbhost' as user '$dbuser'. Error returned was: ". $DBI::errstr ."";

my $sth = $dbh->prepare('SELECT COUNT(*) FROM employee;');

for (;;)
{
$sth->execute();
my ($count) = $sth->fetchrow();
print "count=$count\n";
$sth->finish();
# $dbh->commit;
sleep(3);
}

$dbh->disconnect;

--
http://www.wiesinger.com/

On Thu, 24 Sep 2009, Craig James wrote:

> Dave Dutcher wrote:
>> You need a COMMIT for every BEGIN. If you just run a SELECT statement
>> without first beginning a transaction, then you should not end up with a
>> connection that is Idle in Transaction. If you are beginning a
>> transaction,
>> doing a select, and then not committing, then yes that is a bug.
>
> The BEGIN can be hidden, though. For example, if the application is written
> in Perl,
>
> $dbh = DBI->connect($dsn, $user, $pass, {AutoCommit => 0});
>
> will automatically start a transaction the first time you do anything. Under
> the covers, the Perl DBI issues the BEGIN for you, and you have to do an
> explicit
>
> $dbh->commit();
>
> to commit it.
>
> Craig
>
>
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>