Thanks Leonard for the great FLIP. I think it is in very good shape. +1 to start a vote.
Best, Jark On Fri, 31 Jul 2020 at 17:56, Fabian Hueske <fhue...@gmail.com> wrote: > Hi Leonard, > > Thanks for this FLIP! > Looks good from my side. > > Cheers, Fabian > > Am Do., 30. Juli 2020 um 22:15 Uhr schrieb Seth Wiesman < > sjwies...@gmail.com > >: > > > Hi Leondard, > > > > Thank you for pushing this, I think the updated syntax looks really good > > and the semantics make sense to me. > > > > +1 > > > > Seth > > > > On Wed, Jul 29, 2020 at 11:36 AM Leonard Xu <xbjt...@gmail.com> wrote: > > > > > Hi, Konstantin > > > > > > > > > > > 1) A "Versioned Temporal Table DDL on source" can only be joined on > > the > > > > PRIMARY KEY attribute, correct? > > > Yes, the PRIMARY KEY would be join key. > > > > > > > > > > > 2) Isn't it the time attribute in the ORDER BY clause of the VIEW > > > definition that defines > > > > whether a event-time or processing time temporal table join is used? > > > > > > I think event-time or processing-time temporal table join depends on > fact > > > table’s time attribute in temporal join rather than from temporal table > > > side, the event-time or processing time in temporal table is just used > to > > > split the validity period of versioned snapshot of temporal table. The > > > processing time attribute is not necessary for temporal table without > > > version, only the primary key is required, the following VIEW is also > > valid > > > for temporal table without version. > > > CREATE VIEW latest_rates AS > > > SELECT currency, LAST_VALUE(rate) -- only keep the latest > > > version > > > FROM rates > > > GROUP BY currency; -- inferred primary key > > > > > > > > > > > > > > 3) A "Versioned Temporal Table DDL on source" is always versioned on > > > > operation_time regardless of the lookup table attribute (event-time > or > > > > processing time attribute), correct? > > > > > > > > > Yes, the semantics of `FOR SYSTEM_TIME AS OF o.time` is using the > o.time > > > value to lookup the version of the temporal table. > > > For fact table has the processing time attribute, it means only lookup > > the > > > latest version of temporal table and we can do some optimization in > > > implementation like only keep the latest version. > > > > > > > > > Best > > > Leonard > > >
