On Mon, Oct 17, 2016 at 08:04:43AM -0500, Kevin Grittner wrote: > > We have regression test for this feature but it sets > > old_snapshot_threshold = 0, I doubt about we can test it properly. > > Am I missing something? > > This is a hard feature to test properly, and certainly hard to test > without the test running for a long time. The zero setting is > really not intended to be used in production, but only to allow > some half-way decent testing that doesn't take extreme lengths of > time. If you add some delays of a few minutes each at key points > in a test, you should be able to get a test that works with a > setting of 1min. It is not impossible that we might need to add a > memory barrier to one or two places to get such tests to behave > consistently, but I have not been able to spot where, if anywhere, > that would be.
Slide 10 of this presentation has an example showing old_snapshot_threshold set to '1min': http://momjian.us/main/writings/pgsql/features.pdf -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription + -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers