Re: Yet another "drop table vs delete" question - Mailing list pgsql-general

On Apr 21, 2009, at 2:15 PM, Jeff Davis wrote:
> In Session1, the serializable transaction sees an empty version of
> bar,
> even though it had tuples in at the time Session1 got its serializable
> snapshot.

Indeed so, and I understand that part.  But since Session1 didn't try
to access 'bar', it can't distinguish that sequence from:

Session2:
  BEGIN;
  TRUNCATE bar;
  COMMIT;

Session1:
  BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;
  SELECT * FROM foo;
  SELECT * from bar;
  COMMIT;

I've been trying to come up with a scenario in which a TRUNCATE
violates concurrency expectations; I'm sure one exists, but my brain
isn't wrapping around it.