On Sat, Aug 18, 2018 at 9:28 AM Enrico Olivelli <eolive...@gmail.com> wrote:
> Il sab 18 ago 2018, 17:26 Sijie Guo <guosi...@gmail.com> ha scritto: > > > On Sat, Aug 18, 2018 at 2:12 AM Enrico Olivelli <eolive...@gmail.com> > > wrote: > > > > > Nice work Sijie, > > > Some comments after the first read, just thinking out loud... > > > Overall looks a good idea and implementable. > > > > > > We should cite somewhere the case of scope=0 and ledgerId = -1 which > is a > > > very special case for usthe. > > > > > > > For BC reason, negative ledger id are not supported when scope == 0. We > > effectively only support 63 bit. > > > > Fine to me > > We should state clearly in the BP and then in javadocs and docs that not > the full 128bit space is handled, but there is a class of combinations > which won't work (scopeid = 0 and ledgerid < 0). > Sure. But I think that would be clearly until we implement it. So I would defer the clarification until then. Because there can be other more corner cases. > > > > > > > We can use versions on clients to distinguish whether they are old > clients > > or new clients, then handle this case differently. > > > > So this special case should not be special for any new clients. > > > > We should also state that scopeid and ledgerid < 0 is not supported or it > > > is not clear to me how we will handle that case. > > > The case of scope < 0 is not clear to me as well, maybe I have to read > > more > > > carefully the doc. > > > > > > I think I answer this with my comment above. > > > > > > > > > > We are treating the global space of ledgerids as a 2 level hierarchy > and > > > this is good for compatibility. > > > But thinking about a new application, which starts with uuids I think > it > > > can be tricky, maybe we should add utilities/APIs to work with UUID > > > directly. > > > > > > The ledgerQualifiedName is the hex presentation of UUID, proposed to add > to > > CLI tool. > > > > We can add it to API as well. However I would defer adding it until we > need > > it or after we are on 128 bits. BC is the top concern. > > > > > > > For this new kind of application the space of ids would be flat and not > > > hierarchical (UUID are not hierarchical as far as I know, but I may be > > > wrong). > > > > > > In a lot of places, 128 bit is not well supported. So people would divide > > into two parts any way, msb and lsb. > > > > > > > > > > > > > We should also support listing the whole flat space > > > > > > Sure it can be added. I don’t see a reason we can’t. However IMO these > are > > new features after we are on 128 bit. For the concerns in this BP, we are > > more focused on how we can transition from 64 bit to 128 bit. > > > > Okay > > Last comment: > We are going to have a lot of special cases in layout of data/zk ledger > manager, to handle scopeid = 0. > I am thinking to a brand new installation, without upgrade/BC concerns, I > wonder if we have some flag not to have that tricks, I am talking about the > different dbs on rocks db, the layout of indexes...and so on. I don’t think we should provide this flag since it would make things very complicated. In that case, you can just provide a brand new metadata driver, a new ledger storage. The you don’t need to worry about this upgrade story. However that will be brand new implementation, which would be out of the scope of this BP. Sijie > > This is not a real problem but I wonder if we ca handle this case of new > applications cleanly > > Enrico > > > > > or as a last > > > alternative we should add a way to list the space of scopeids, because > > > otherwise the application must store the list of scopeids, and for it > it > > > will be a set of half UUIDs. > > > > > > Thanks for driving this > > > > > > Enrico > > > > > > > > > > > > Il ven 17 ago 2018, 23:52 Venkateswara Rao Jujjuri <jujj...@gmail.com> > > ha > > > scritto: > > > > > > > Thanks a lot, Sijie for the awesome doc. > > > > Let's pool some more thoughts into this and size the work. > > > > > > > > Thanks, > > > > JV > > > > > > > > On Fri, Aug 17, 2018 at 2:36 PM, Sijie Guo <guosi...@gmail.com> > wrote: > > > > > > > > > Hi all, > > > > > > > > > > As promised in last community meeting, I put up all the thoughts > and > > > > > discussion with JV I had into a BP for supporting 128-bit ledger > id. > > I > > > > > tried my best to cover all the aspects that I can think of. There > can > > > be > > > > > places that I miss. so please take a look and let me know what you > > > think. > > > > > > > > > > BP PR: https://github.com/apache/bookkeeper/pull/1611 > > > > > Google doc: > > > > > https://docs.google.com/document/d/1cu54dNSV2ZrdWCi40LcyX8NxXGRCW > > > > > 0609T_ewmK9BWM > > > > > > > > > > - Sijie > > > > > > > > > > > > > > > > > > > > > -- > > > > Jvrao > > > > --- > > > > First they ignore you, then they laugh at you, then they fight you, > > then > > > > you win. - Mahatma Gandhi > > > > > > > -- > > > > > > > > > -- Enrico Olivelli > > > > > > -- > > > -- Enrico Olivelli >
