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Posted to modperl@perl.apache.org by Andre Landwehr <an...@gmx.net> on 2000/02/21 11:55:07 UTC
storing db handles
Hi,
I use Embperl and I have a test- and a production environment which
use different databases and persistent connections via
Apache::DBI. Since I do not want to change the connection string
in each file I copy from test to production I need either a
global database handle or a mechanism which returns a valid
handle for the current environment. I have two ideas about how to do this:
1) Put the statement into httpd.conf which will make $dbh global
for all Apache childprocesses. How will Apache::DBI react to
this, will it still create new connections if the one
predefined in httpd.conf is in use or is Apache::DBI useless
in this case?
2) Write a component doing nothing but establishing the db-connection
and saving the database handle in %udat. The component is then called
via 'Execute'. As I understand, a handle can only be used by
the one Apache child it was created with, so I have to Execute
that component in every page. The loss in performance should
not be overwhelming and Apache::DBI should guarantee
that still no more db-connections than needed get established.
Since I am not very experienced with this stuff I would like to
hear what the gurus think about this ;-)
Andre
Re: storing db handles
Posted by Andre Landwehr <an...@mini.gt.owl.de>.
On Mon, Feb 21, 2000 at 10:25:30AM -0500, Brendan W. McAdams wrote:
> I did this [my mod_perl is pretty horrible but it works well so bear with
> me] for my startup file:
(...)
> Apache->push_handlers("PerlChildInitHandler" => sub { $dbh =
> DBI->connect("dbi:mysql:<database>","<username>","<password>"); } );
> Apache->push_handlers("PerlChildExitHandler" => sub
> $dbh->disconnect; } );
(...)
> My actual modules for the site have these directives:
>
> my $dbh ||= DBI->connect("dbi:mysql:$database","$db_user","$db_pass") ||
> return SERVER_ERROR;
Thanks, but this does not really help since I still have the
name, user and password in each of my modules. Is there a way to
access the $dbh from the PerlChildInitHandler directly without
providing this information each time?
Andre
Re: storing db handles
Posted by "Brendan W. McAdams" <br...@plexmedia.com>.
I did this [my mod_perl is pretty horrible but it works well so bear with
me] for my startup file:
#!/usr/local/bin/perl
# Brendan W. McAdams <br...@plexmedia.com>
# Copyright (c) 2000, Plexus InterActive
#init.
BEGIN {
use lib '/home/httpd/sites/web/cgis/www.artizenuniverse.com/lib';
use Apache();
use Apache::DBI;
Apache->push_handlers("PerlChildInitHandler" => sub { $dbh =
DBI->connect("dbi:mysql:<database>","<username>","<password>"); } );
Apache->push_handlers("PerlChildExitHandler" => sub
$dbh->disconnect; } );
}
# includes.
use Apache::Constants();
# globals for apache.
my $dbh;
1;
This then connects a $dbh for each CHILD (globalising the database handler
for the entire apache process is from what i've seen and read dangerous and
unstable - give each child a child scoped handle... I've found this to be
very stable.
Apache::DBI handles the connection quite well and manages it continually.
My actual modules for the site have these directives:
my $dbh ||= DBI->connect("dbi:mysql:$database","$db_user","$db_pass") ||
return SERVER_ERROR;
hope this helps
-brendan
-----
Brendan W. McAdams | email: brendan@plexmedia.com
Programmer/Systems Administrator | office: (305)377-2880
Plexus InterActive | pager: (305)277-4879
http://www.plexmedia.com | cell phone: (305)401-7313
"Always listen to the experts - they'll tell you what can't be done and why.
Then do it."
-Robert A. Heinlein
----- Original Message -----
From: "Andre Landwehr" <an...@gmx.net>
To: "Brendan W. McAdams" <br...@plexmedia.com>
Sent: Monday, February 21, 2000 9:47 AM
Subject: Re: storing db handles
On Mon, Feb 21, 2000 at 08:08:11AM -0500, Brendan W. McAdams wrote:
> I was approaching a similar problem recently .... I found some info on
Apache::DBI in the Mod_Perl developers guide that may help.
> Basically though I globalised $dbh and then made my connection code this:
>
> $dbh ||= DBI->connect("dbi:mysql:$database","$db_user","$db_pass");
>
> And then setup a child init handler to open up a $dbh on apache startup,
which gives each child a persistant connection.
Could you please show me how to do this? I tried to just write
----
my $dbh = DBI->connect("dbi:Sybase:server=myserver", "user", "pwd",
{PrintError => 0});
die "Unable for connect to myserver: $DBI::errstr" unless $dbhcharts;
-----
into my startup.pl and wrote "use vars qw($dbh)" into my Embperl
pages, but $dbh seems to be undefined.. thanks in advance..
Andre
Re: storing db handles
Posted by "Paul J. Lucas" <pj...@barefooters.org>.
On Mon, 21 Feb 2000, Brendan W. McAdams wrote:
> I found some info on Apache::DBI in the Mod_Perl developers guide that may
> help. Basically though I globalised $dbh and then made my connection code
> this:
>
> $dbh ||= DBI->connect("dbi:mysql:$database","$db_user","$db_pass");
Unless I'm misreading the Apache::DBI manual page, this is
completely unnecessary. Apache::DBI makes persistent
connections transparent so you can call connect() and
disconnect() as normal. You don't need to do one-time
initializations, global variables, or anything.
- Paul
Re: storing db handles
Posted by "Brendan W. McAdams" <br...@plexmedia.com>.
I was approaching a similar problem recently .... I found some info on Apache::DBI in the Mod_Perl developers guide that may help.
Basically though I globalised $dbh and then made my connection code this:
$dbh ||= DBI->connect("dbi:mysql:$database","$db_user","$db_pass");
And then setup a child init handler to open up a $dbh on apache startup, which gives each child a persistant connection.
I tested it for about 3 days and this was very stable and the database connection very reliable.
-Brendan
--
Brendan W. McAdams | Home/Cell: (305)401-7313
Programmer/Systems Administrator | Work: (305)377-2880
Plexus InterActive | email:brendan@plexmedia.com
http://www.plexmedia.com
"Always listen to experts. They'll tell you what can't be done, and why. Then
do it. "
-- Robert A. Heinlein
----- Original Message -----
From: Andre Landwehr <an...@gmx.net>
To: Modperl List <mo...@apache.org>
Sent: Monday, February 21, 2000 5:55 AM
Subject: storing db handles
Hi,
I use Embperl and I have a test- and a production environment which
use different databases and persistent connections via
Apache::DBI. Since I do not want to change the connection string
in each file I copy from test to production I need either a
global database handle or a mechanism which returns a valid
handle for the current environment. I have two ideas about how to do this:
1) Put the statement into httpd.conf which will make $dbh global
for all Apache childprocesses. How will Apache::DBI react to
this, will it still create new connections if the one
predefined in httpd.conf is in use or is Apache::DBI useless
in this case?
2) Write a component doing nothing but establishing the db-connection
and saving the database handle in %udat. The component is then called
via 'Execute'. As I understand, a handle can only be used by
the one Apache child it was created with, so I have to Execute
that component in every page. The loss in performance should
not be overwhelming and Apache::DBI should guarantee
that still no more db-connections than needed get established.
Since I am not very experienced with this stuff I would like to
hear what the gurus think about this ;-)
Andre
Perl Section...
Posted by "Bryan J. Opfer" <op...@ivenue.com>.
Anyone know what this error would mean:
DBI handle cleared whilst still active at
/usr/lib/perl5/site_perl/5.005/i386-linux/DBI.pm line 195.
dbih_clearcom (h 0x83b1900, com 0x81b6d50):
FLAGS 0x211: COMSET Warn AutoCommit
TYPE 1
PARENT undef
KIDS 0 (0 active)
IMP_DATA undef in 'DBD::mysql::dr'
This error comes up in my apache error log. I have a Perl section in my
httpd.conf that sets up all my virtual hosts.
Apache starts up fine, but the virtual hosts are not set up and I get
that error in the error log. I am using Apache 1.3.12 compiled from
source.
I have the same setup on another machine with Apache 1.3.9 (RPM) and it
works fine.
DBI is version 1.13.
Thanks,
Bryan Opfer