On Thu, May 5, 2016 at 8:44 AM, Andres Freund <andres@anarazel.de> wrote: > > On 2016-05-05 06:08:39 +0300, Ants Aasma wrote: > > On 5 May 2016 1:28 a.m., "Andres Freund" <andres@anarazel.de> wrote: > > > On 2016-05-04 18:22:27 -0400, Robert Haas wrote: > > > > How would the semantics change? > > > > > > Right now the time for computing the snapshot is relevant, if > > > maintenance of xids is moved, it'll likely be tied to the time xids are > > > assigned. That seems perfectly alright, but it'll change behaviour. > > > > FWIW moving the maintenance to a clock tick process will not change user > > visible semantics in any significant way. The change could easily be made > > in the next release. > > I'm not convinced of that - right now the timeout is computed as a > offset to the time a snapshot with a certain xmin horizon is > taken.
Here are you talking about snapshot time (snapshot->whenTaken) which is updated at the time of GetSnapshotData()?