On Thu, Jun 30, 2022 at 2:07 PM David G. Johnston <david.g.johns...@gmail.com> wrote: > Current: > "The SET and WHERE clauses in ON CONFLICT DO UPDATE have access to the > existing row using the table's name (or an alias), and to [rows] proposed > for insertion using the special excluded table." > > The word table in that sentence is wrong and not a useful way to think of the > thing which we've named excluded. It is a single value of a composite type > having the structure of the named table.
I think that your reasoning is correct, but I don't agree with your conclusion. The term "special excluded table" is a fudge, but that isn't necessarily a bad thing. Sure, we could add something about the UPDATE being similar to an UPDATE with a self-join, as I said upthread. But I think that that would make the concept harder to grasp. > I'll agree that most people will mentally paper over the difference and go > merrily on their way. At least one person recently did not do that, which > prompted an email to the community Can you provide a reference for this? Didn't see anything like that in the reference you gave upthread. I have a hard time imagining a user that reads the INSERT docs and imagines that "excluded" is a relation that is visible to the query in ways that are not limited to expression evaluation for the UPDATE's WHERE/SET. The way that it works (and doesn't work) follows naturally from what a user would want to do in order to upsert. MySQL's INSERT ... ON DUPLICATE KEY UPDATE feature has a magical UPSERT-only expression instead of "excluded". -- Peter Geoghegan
