On Friday, 25 January 2019 04:57:15 UTC+8, Jeremy Finzel wrote: > > We are working to migrate several large tables from the timestamp to the > timestamptz data type by using logical replication (so as to avoid long > downtime for type conversions). We are using pglogical but curious if what > I share below applies to native logical replication as well. > > Both source and destination dbs are at localtime, which is > 'America/Chicago' time zone. > > The source system has a timestamp stored "at time zone UTC", like this for > 6:00pm Chicago time: > 2019-01-24 20:00:00.000000 > > I was *very surprised* to find that replicating above timestamp to > timestamptz actually does so correctly, showing this value in my psql > client on the subscriber: > 2019-01-24 14:00:00.000000-06 > > How does it know/why does it assume it knows that the time zone of the > timestamp data type is UTC on the provider given that my clusters are at > America/Chicago? I would have actually expected an incorrect conversion of > the data unless I set the timezone to UTC on the way in on the subscriber > via a trigger. > > That is, I was expecting to see this: > 2019-01-24 20:00:00.000000-06 > > Which is obviously wrong. So why does it do this and is there some > assumption being made somewhere in the code base that a timestamp is > actually saved "at time zone UTC"? > > pglogical is replicating the timestamp text, which is converted on both output and input.
