I've got a Solr 9.1 master and slave. I have set up replication. The instances runs in containers.
When the slave starts up, I request http://localhost:8983/solr/[core]/replication?command=fetchindex in that slave to retrieve the index. However, this always gives the following error :
2022-12-16 14:57:58.159 INFO (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher Leader's generation: 658
2022-12-16 14:57:58.160 INFO (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher Leader's version: 1671202320920
2022-12-16 14:57:58.160 INFO (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher Follower's generation: 1
2022-12-16 14:57:58.160 INFO (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher Follower's version: 0
2022-12-16 14:57:58.160 INFO (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher Starting replication process
2022-12-16 14:57:58.164 ERROR (explicit-fetchindex-cmd) [] o.a.s.h.IndexFetcher No files to download for index generation: 658
The slave refuse to replicate from the master until I have run http://localhost:8983/solr/[core]/update?optimize=true on the master.
However, I then need to hurry up and initiate a replication from the slave, because the slave will only replicate the master if Leader (Searching) and Leader (Replicable) matches.
Screenshot from the master :
As soon as Leader (Searching) and Leader (Replicable) no longer match, the slave again refuse to replicate.
The slave probably refuse to replicate simply because it is unable to. If I request http://localhost:8983/solr/[core]/replication?command=filelist&generation=667 on the master, I get :
{
"responseHeader":{
"status":0,
"QTime":0},
"status":"ERROR",
"message":"invalid index generation"}
The Leader (Searching) value increases all the time, because indexing and commits are happening.
I find it hard to believe that this is by design. Should slaves really not be able to replicate from the master when Leader (Searching) and Leader (Replicable) do not match?
