Re: from pgsql_perl5 (Pg) to DBD::Pg

Bob Hunter wrote:
>> What parts are you having trouble with?
>>     
>
> To start with, a DBD::Pg not backward compatible with
> Pg. The original program must be back into production
> in a few hours; for this to be possible, I have to
> instruct the original code to use DBD:Pg, with minimum
> or no changes at all. 
This is not possible, as you have noted that DBD::Pg is not backward 
compatible.  I would suggest you implement a modified version of the 
code in a testing environment and when the modified version of the new 
code passes your code tests, you switch over to using the new code.  A 
goal of having a production system down for a few hours while you make 
all the necessary changes to go from Pg to DBD::Pg is not at all realistic.

> To rewrite the application is
> out of question. Therefore, I need a cut-through
> introduction on how to port a Pg-based program to
> DBD::Pg. I cannot possibly go trough the whole gamut
> of documents, because I do not have the time for it.
>   
Unfortunately, it is not going to be as simple as a find-and-replace.  
And there is not a whole gamut of documents.  The DBI docs are the docs 
of import (http://search.cpan.org/~timb/DBI-1.53/DBI.pm ).  The code 
will probably not need to be altered much, but I don't see how you can 
possibly hope to convert your old code to new without understanding what 
you are going to change it to.  You will not need to rewrite the 
application, but you will need to make modifications to the way the 
application accesses the database.  As I mentioned above, I would 
present this to your supervisor (if there is one) as a replacement of 
the original application.  As such, the project will need proper 
planning, testing, and time.  A few hours (unless this is a pretty 
straightforward application that is not mission-critical) is not going 
to cut it.  So, stick with the Pg version (that is presumably serving 
most of your needs), implement and test the new code, and then make the 
switch.

Sean