Hi, Replication when everything is working well is push: * request comes to any node, ideally leader * doc is indexed on leader * doc is copied to replicas
If replica falls too far behind (not exactly sure what the "too far" threshold is), it uses pull to replicate the whole index from leader. Mark can answer the part about where tlog gets replayed to catch up on docs that were missed while big index replication pull was happening. This is a good thread to read on this topic: http://search-lucene.com/m/y1yj218J2v82 Otis -- Solr & ElasticSearch Support http://sematext.com/ On Tue, Apr 16, 2013 at 1:36 AM, SuoNayi <suonayi2...@163.com> wrote: > Hi, can someone explain more details about what model is used to sync docs > between the lead and > replica in the shard? > The model can be push or pull.Supposing I have only one shard that has 1 > leader and 2 replicas, > when the leader receives a update request, does it will scatter the request > to each available and active > replica at first and then processes the request locally at last?In this case > if the replicas are able to catch > up with the leader can I think this is a push model that the leader pushes > updates to it's replicas? > > > What happens if a replica is behind the leader?Will the replica pull docs > from the leader and keep > a track of the coming updates from the lead in a log(called tlog)?If so when > it complete pulling docs > it will replay updates in the tlog at last? > > > > > regards > > > > > > >
