[ CC'ing Edmund on this thread in case he is not on the dbi-users list]
Tim Bunce wrote:
> On Tue, Apr 30, 2002 at 03:34:26PM -0400, Geoffrey Young wrote:
>
>>hi Tim and all - it's been a long time :)
>>
>>Stas and I just ran across something interesting concerning Apache::DBI and $dbh
>>attributes. I think it involves a both a bug and a place for enhancements.
>>
>>we all know how Apache::DBI works - it stashes away $dbh based on connect string
>info.
>>however, connect string info is limiting, so nice thing to do is strip down your
>connect()
>>call to the bare minimum and add attributes to $dbh after the fact:
>>
>>my $dbh = DBI->connect($dbase, $user, $pass);
>>$dbh->{AutoCommit} = 0;
>
>
> Don't do that.
>
> It (connect_cached) stashes away $dbh based on connect string info
> *and* all the attributes. You should set all the atributes you
> require in the connect() and then not change them later.
>
> That way connections that require different attributes are sure to
> get different handles.
That's actually a mod_perl advisory. Since if you have two scripts
wanting to reuse the same connection via Apache::DBI they *must* use the
exactly the same connect string. Now if one script wants LongReadLen =
40 and the other LongReadLen = 80, they have to modify that after
connect(). If they supply different connect strings, the service will
need roughly a twice bigger number of connection, and so on.
Is it possible to deep copy $dbh, when handing it off
Apache::DBI::connect()? Then any changes will be local and won't affect
the cached copy.
>>to take this a step further, what would be really DWIMy is for DBI to clear all of
>the
>>$dbh attributes not specified in the connect() call (including stuff like
>LongReadLen) if
>>dbi_connect_method = 'Apache'. that seems like the right thing, since with
>Apache::DBI
>>wat we want a "new" $dbh, just without the connect overhead. and DBI seems like a
>>reasonable place to do it, especially since DBI->connect is kinda
>action-at-a-distance
>>anyway wrt Apache::DBI.
>>
>>maybe I'm missing something design-wise, though?
>
>
> I think the Apache::DBI subclass can override the STORE method and
> track attribute changes itself.
That sounds like a good solution. Edmund?
I raised this issue, since in the mod_perl book Eric and I are working
on, we say that the connect string shouldn't change in order to be able
to reuse connections. I guess we must warn users that any changes to
$dbh will persist, which renders the advisory useless and doesn't
provide any solution :(
__________________________________________________________________
Stas Bekman JAm_pH ------> Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide ---> http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org http://ticketmaster.com
