Forum OpenACS Improvement Proposals (TIPs): TIP #31: (Approved for 5.1) Make db_multirow unclobber by default
I believe any upgradability difficulties caused by this change (which I estimate to be small) in the long run will be outweighed by the improved robustness of the toolkit.
Yes, I think that Lars pointed out that db_multirow, when used without the foreach loop doesn't clobber. I believe this was the original design, and then someone added the foreach loop, which was a great idea, but they added the clobbering features of db_foreach as well. This makes db_multirow act differently if you later decide to extend a row, and do so by using the foreach loop. Suddenly things start to break and you have to rethink your entire page.
The main purpose of db_multirow is to create the datasource in an array format, so the question really is whether the the switch should be clobber or unclobber?
If clobbering is the default, I doubt it will quicken bug squashing caused by forgetting the switch. However folks will quickly find the cause if unclobbering is the default, since none of their variable will exist if they thought they should.
One other point: if clobbering is the default, a multirow will not leave the page in a predictable state. it will depend on the last row of the select statement. The only reason to use a db_multirow in this case is when you really want to use db_1row and also use the features of db_foreach/db_multirow.