Thanks, Norbert!
On Mon, May 12, 2014 at 11:38 AM, Norbert Hartl <norb...@hartl.name> wrote: > > Am 12.05.2014 um 10:46 schrieb Sabine Knöfel <sabine.knoe...@gmail.com>: > > Hi Norbert, > > what about objects which have been written to mongo with the old version > and will be read with the new version. Can they be read/found with the new > version? Or is there a migration needed? > > > I’d say it should be safe just to upgrade the code. The exisiting ids > won’t change because encoding and decoding are always fully reversible. > Meaning regardless of the encoding scheme the ids are the same in the > database after being read and written. The only thing changes is the value > in the OID object in your image. There are two ways where this can fail. > Either you monkey with id values inside your code. Or you use manual > references to objects where the referenced id is not written as OID. > Everything else should be the same with the old and the new code. > In the meantime I even changed the generation of the id value to reflect > the mongo spec. Now the values should be comparable to what other drivers > (including mongo shell) are generating. This also means you can now ask > your ObjectId about its timestamp. Which of course gives you non-sense with > ids generated prior to the code update.. > > Norbert > > > > On Thu, May 8, 2014 at 11:30 PM, Norbert Hartl <norb...@hartl.name> wrote: > >> I needed to change the way ObjectIds are read from and written to BSON. >> BSON is a format that encodes its byte contents little endian. In mongo >> database the format of ObjectIds is different. The way an ObjectId is >> encoded is big endian. You can see this if you compare the outputs for an >> object when read from mongo shell and from pharo. The ids won’t match. >> >> If you do „normal“ stuff with mongo it is unlikely you have noticed the >> effect. An OID is read the wrong way but also written the wrong way which >> makes it right again from the mongo database perspective. But it won’t work >> if you use a mixed query setting. Meaning reading an OID and requesting the >> database using javascript expression. This will fail. >> >> I’m writing this because I’m not sure the change can break existing >> software. The change is not included in the stable version, yet. If you >> want to test then load #bleedingEdge and report any problem that might >> occur. I will use the new behaviour and will take the freedom to make it >> stable if it works for some time. >> >> FYI, >> >> Norbert >> >> >> > >
