Hello, I'm in doubt. Assuming you use https://solr.apache.org/guide/solr/latest/query-guide/join-query-parser.html#joining-multiple-shard-collections Please confirm. There;s no exact coordinator test for shard joins here https://github.com/apache/solr/blob/main/solr/core/src/test/org/apache/solr/search/join/ShardToShardJoinAbstract.java#L58 But it creates 5 nodes for 3 shard collections, and I believe pick a coordinator randomly. So, we may expect it's working. Then, the error you provide might occur at "to"-node when it didn't find expected co-shard. I'm afraid we need to check shard alignment across cluster, and detailed request log across nodes. what exactly happened at coordinator and subordinate nodes. Regarding shards allocation: even if there's a node with a shard1 of "to" collection collocated with "from" shard1, nothing will stop the coordinator from attempting to search "to" shard1 at another node where "from" shard1 is absent, and got the error like this.
On Tue, Mar 3, 2026 at 6:02 PM Endika Posadas <[email protected]> wrote: > Hi, > > We're running dedicated coordinator nodes for query performance, with > collections that are properly co-located across data nodes. > > > When sending a join query (fromIndex pointing to a co-located collection) > through the coordinator, we get an error: > > "error":{ > > "metadata":["error-class","org.apache.solr.common.SolrException","root-error-class","org.apache.solr.common.SolrException"], > "msg":"SolrCloud join: To join with a collection that might not be > co-located, use method=crossCollection.", > "code":400 > } > > > The same query works fine when sent directly to a data node. > > It seems like the coordinator is trying to resolve the join instead of > delegating it to the data nodes. Is there a workaround around this? > > Thanks > -- Sincerely yours Mikhail Khludnev
