Yes, that could be an option if this was supposed to be a permanent script. However, I was trying very hard to finish the migration of the deals to the new template and the script was quite big and complex. I didn't talk about the script so that I could focus on this specific part that affected it, but the way some people are judging it's like I had put a lot of thoughts in this part of script. It wasn't the case. This was a minor part of the script. I hadn't thought about using nextval() to create the mapping table when I first wrote the script, so it looked like adding a temporary column to store the old id would be the simplest solution for the mapping problem. I had that gut feeling telling me it wasn't the right thing but as long as it worked, for a one-off script, I didn't really care if it allowed me to finish the porting earlier. Writing a trigger would take more time and code than adding a temporary column, just like using nextval() to create the temp table is less work than writing the trigger. Most people seem to ignore that this was a one-off script that won't ever be used again.

I don't actually regret my approach. It allowed me to deliver the first version for testing earlier and I was able to fix the script later in less than an hour once the problem happened. Maybe other parts of the script were not ideal either, but the migration was successful and this is what really matter to me. It would be a completely different situation if I was writing a permanent code. In those cases I write the code way more carefully and give it quite a lot of thoughts on the future implications.