At 11:10 mentions a blog post about optimistic walking on engine yard
At 1445 race condition in unique in rails. It does a select and if there is no record it will write, but something else could be written in that very short timeframe
At 1510 all six of the problems in the talk can be addressed with database constraints
database-constraints-vs-app-constraints
At 1620 he talks about a blog post that DHH made early on that explains that he only wants to think about validations at the model there. He then explains that he thinks that was the wrong choice.
At 1710 he talks about how a lot of these issues seem to have arisen from people not understanding what was happening at the data base layer. There is some talk about why not database constraints, but it is primarily the developers want the logic in one place pier
At 1850, the DBA said if it can be constrained, then constraint it.
At 3530 there are a lot of ways to skip model validations, some of them in advertently. The examples he gave were complicated.
At 3930 when you add a new validation nothing in rails ensures that the existing data matches that new validation.
At 47 when talking about legacy code the question is whether the decisions were happenstance or important