[Koha-devel] about C4Connect

[Alan Millar]

On Mon, Jun 10, 2002 at 10:52:42PM +0200, paul POULAIN wrote:
> I i'm right, every DB function begins by a $dbh=&C4Connect.
> Connecting to a DB is a HIGH time-cost function.

I agree.  The current method works fine for small, lightly loaded
systems.  If we want Koha to scale, and want it to be portable to
other DB engines where the DB open may be an even bigger
performance hit, we should change the current practice.

> The solution to this problem would be to have only one $dbh=&C4Connect 
> at the beginning of every .pl script, this $dbh variable being used by 
> every sub.

I think this is where we need to go.  Yes, it is the most work, but I'd
rather see us phase in the right solution over time than change a bunch of 
subroutines quickly for a short-sighted solution.

> One solution would be to rebuild all sub calls to add a dbh parameter, 
> but i'm sure there is a solution to declare a global variable, which 
> would be used if there is no "my $dbh" in the .pm sub...
> What's the best solution in Perl to do this ? ("our" may be used with 
> packages, but what i want is to have the C4Connect at the beginning of 
> every .pl script)

I'd like to avoid undocumented side effects in subroutines.  What happens
at some point in the future when you might want two different databases
open, but you can only use the subroutine on one of them because the
database handle depends on a global variable with a fixed variable name?  
"Oh, we'll never need that...." :-)

I just spent the last week unravelling a script that didn't do "use strict",
and chasing down the side effects of undeclared variables and global 
variables used in subroutines was a mess.  Let's not do more of that :-)

- Alan

----
Alan Millar     --==> am12 at bolis.com <==--