Alejandro - Yeah, I think that is an older pattern that while considered "common", also isn't actually what I would call best practice. Lots of us run single core/shard setups, but use SolrCloud so we get access to the better APIs. Merging standalone and SolrCloud into a single mode is something on my list for the future. More to come on that topic.
On 2026/03/12 19:05:44 "Arrieta, Alejandro" wrote: > Hello David and team, > > >>Out of curiosity, why would scaling down to 1 and back up to N not be an > already supported pattern? > > I may be wrong, but generally if you use Solr with only one core/shard you > don't use solr cloud/zookeeper. At least in older Solr versions. > > Kind regards, > Alejandro Arrieta > > > On Thu, Mar 12, 2026, 9:29 AM David Eric Pugh via dev <[email protected]> > wrote: > > > Jan, so if my world doesn't include Kubernetes, it would be a reasonable > > addition to Solr to ship a placement plugin that scales up and down the > > single shard collections that use it. And does the book keeping in > > ZooKeeper to not show down nodes or down replicas? > > Not sure how complex the engineering on this will be! > > Out of curiosity, why would scaling down to 1 and back up to N not be an > > already supported pattern? Is it because everyone does that with their own > > scripts external to Solr or via the Operator? What am I missing about this > > use case? > > > > On Thursday, March 12, 2026 at 08:27:15 AM EDT, David Eric Pugh < > > [email protected]> wrote: > > > > David --> I oddly struggled to write the email cause I was stumbling > > over my words... I wasn't sure if I should have said "shard", and how to > > phrase a collection made up of a single core.... And then copies of that > > core... After I read your response, I thought, I should check out the > > Solr Concepts page and see what it tells me and discovered that we have > > nothing under Solr Concepts specific to this topic. I looked up in the > > glossary "SolrCloud" and it led me to > > https://solr.apache.org/guide/solr/latest/deployment-guide/cluster-types.html#solrcloud-mode. > > Only later when I scrolled up in the page did I see the section "Cluster > > Concepts". Thoughts on maybe moving that section under the Solr Concepts > > hierarchy in Ref Guide? It would have helped me use the right terms! > > > > > > > > > > On Wednesday, March 11, 2026 at 06:38:17 PM EDT, David Smiley < > > [email protected]> wrote: > > > > An aside: Remember that the leader is a replica too, so your numbers are > > off & confusing. "single shard with no replicas" -- I guessed what you > > mean but surprised to hear a misuse of SolrCloud lingo from you. AFAICT, > > leadership isn't even pertinent to your inquiry either. > > > > On Wed, Mar 11, 2026 at 5:38 PM David Eric Pugh via dev < > > [email protected]> > > wrote: > > > > > Hey all, I wanted to get some feedback from you'all on a recent usecase I > > > was asked about. I suspect the answer will be "Use Solr Operator", but > > > here goes! > > > I have an environment where I have 5 or so single shard collections. > > > Much of the time I run just a single node and each collection is a > > single > > > shard with no replicas. Sometimes, to support load, I'll add another > > node > > > or two. Then I'll add replicas so cover the new nodes, 1 per node. So > > > with three nodes, I have one leader and two replicas. Add two more > > nodes, > > > move to one leader and four replicas. > > > However, when I remove a node by shutting it down, then Zookeeper never > > > get's notified about this, and so the replica is listed as down, and the > > > node is listed as down in red in the UI. When it isn't really red, it's > > > just we don't need it for now, and it's not coming back. > > > I'd like to just declare "For this collection, I want one replica per > > node > > > based on however many nodes are current". I don't want to call the > > > various commands myself to add replicas and or remove then as nodes are > > > added or removed. And I don't want to call various apis or other complex > > > things when I add or remove a node, I just want bin/solr stop and > > bin/solr > > > start to be run ;-). > > > I think this is what Replica Placement Plugins were for maybe? Could I > > > have a Replica Placement strategy that when ZK sees a new node added, > > then > > > creates a new replica on it, and vice versa, when a node goes away, it > > just > > > removes that replica instead of treating it as "down"? > > > Thoughts? > > > Eric > > > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
