Hi Erick, > Before the leader goes down, the sequence of an update is this. > - the doc comes in to the leader (TL) > - the doc is forwarded to all the other tlog replicas (TF) and written to _their_ tlogs > - all the TF replicas ack back to TL > - TL acks back to the client
So the write request doesn't return a response until all the tlog replicas have been written! Thank you. BTW, does replication by tlog always work like this? 2020年4月6日(月) 20:42 Erick Erickson <erickerick...@gmail.com>: > You’ve got the sequence, that’s it exactly. > > I don’t quite understand the second part of the question, but let me > address data loss. > > Before the leader goes down, the sequence of an update is this. > - the doc comes in to the leader (TL) > - the doc is forwarded to all the other tlog replicas (TF) and written to > _their_ tlogs > - all the TF replicas ack back to TL > - TL acks back to the client > > So, upon getting success back from the update request, all TLOG replicas > have the > docs in their local tlog files. So when the leadership changes, the new > leader > has all the docs to replay, thus no data loss. > > At that point, the old leader’s tlogs are irrelevant. When it comes back > online, > the sequence is: > > - synch from the new leader, including any tlogs. This effectively erases > the old tlogs > - start writing any new docs into the local tlog > > The old leader then remains a follower until some event changes things > again. > > Best, > Erick > > > On Apr 6, 2020, at 1:53 AM, Taisuke Miyazaki <miyazakitais...@lifull.com> > wrote: > > > > Hi, > > Using solr 7.5.0 on solr cloud, and replica type is tlog. > > > > If a leader dies, how is the re-election of the leader and the > > synchronization of the replicas done? > > > > In my opinion. > > Leader dies→ New tlog replica tries to become Leader→ Replays tlogs not > > reflected in the index→ Becomes Leader > > Is this the right fit first? > > > > Also, when another leader is elected, does it create a tlog that is only > > available to the old leader? (I'm worried about data being lost if the > > tlogs aren't synchronized.) > >
