On Thu, 24 Mar 2022 at 14:56, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Simon Riggs <simon.ri...@enterprisedb.com> writes: > > OK, I see what you mean. There are 2 types of transaction, one that > > reads inside the transaction, one that decides what value to use some > > other way. > > > So now we have 2 cases, both of which generate uniqueness violations, > > but only one of which might succeed if retried. The patch does cover > > this, I guess, by saying be careful, but I would be happier if we can > > also add > > > "this is thought to occur only with multiple unique constraints and/or > > an exclusion constraints" > > Um, what's that got to do with it? The example in > read-write-unique-4.spec involves only a single pkey constraint.
Yes, but as you explained, its not actually a serializable case, it just looks a bit like one. That means we are not currently aware of any case where the situation is serializable but the error message is uniqueness violation, unless we have 2 or more unique constraints and/or an exclusion constraint. > We could add something trying to explain that if the application inserts a > value into a constrained column based on data it read earlier, then any > resulting constraint violation might be effectively a serialization > failure. We could do that as well. -- Simon Riggs http://www.EnterpriseDB.com/
