On Sun, 4 Apr 2021 at 09:12, Bruce Momjian <bruce@momjian.us> wrote:
On Sun, Apr 4, 2021 at 08:35:41AM -0400, Dave Cramer wrote: > > > On Thu, 1 Apr 2021 at 15:39, Bruce Momjian <bruce@momjian.us> wrote: > > On Thu, Apr 1, 2021 at 11:24:48AM -0400, Dave Cramer wrote: > > CTE's don't change the isolation level. I'm not sure what you are getting > at > > here ? > > I think what he/she means here is that all queries in a CTE use a single > snapshot, meaning you don't see changes by commits that happen between > queries that are part of the same CTE. If you were running the queries > separately in read committed mode, you would see those changes, but you > would not see them in repeatable read or serializable transaction mode. > > OK, that makes sense, but I think it is wrong minded to think that this > absolves one of taking isolation into account. > > When you make the first read you will still have to deal with all of the > isolation issues
I have no idea what you are saying above. Why is a SELECT-only CTE not the same as a repeatable-read SELECT-only multi-statement transaction? Are you saying that a SELECT in a CTE doesn't do SELECT FOR UPDATE?
