Details
Major Description
In ZkController.createCollectionZkNode, the doc router is determined by this code snippet:
if (collectionProps.get(DocCollection.DOC_ROUTER) == null) {
Object numShards = collectionProps.get(ZkStateReader.NUM_SHARDS_PROP);
if (numShards == null)
if (numShards == null)
{ collectionProps.put(DocCollection.DOC_ROUTER, ImplicitDocRouter.NAME); }else
{ collectionProps.put(DocCollection.DOC_ROUTER, DocRouter.DEFAULT_NAME); }}
Since OverseerCollectionProcessor never passes on any params prefixed with "collection" other than "collection.configName" in its create core commands, collectionProps.get(DocCollection.DOC_ROUTER) will never be non-null. Thus, it needs to figure out if the router is implicit or compositeID based on if numShards is passed in. However, collectionProps.get(ZkStateReader.NUM_SHARDS_PROP) will also always be null for the same reason collectionProps.get(DocCollection.DOC_ROUTER) is null, and it isn't explicitly set in the code above, so the only way for numShards not to be null is if it's passed in as a system property.
As an example, here's a cluster state that's created as compositeId router, but the collection ZK node says it's implicit:
in clusterstate.json:
"example":{
"shards":{"shard1":{
"range":"80000000-7fffffff",
"state":"active",
"replicas":{"core_node1":{
"state":"active",
"core":"example_shard1_replica1",
"node_name":"localhost:8983_solr",
"base_url":"http://localhost:8983/solr",
"leader":"true"}}}},
"router":"compositeId"},
in /collections/example data:
{ "configName":"myconf", "router":"implicit"}I've not sure if the collection ZK node router info is actually used anywhere, so it may not matter, but it's confusing.
I think the best fix is for OverseerCollectionProcessor to pass on params prefixed with "collection." to the core creation requests. Otherwise, ZkController.createCollectionZkNode can explicitly set the numShards collectionProps by cd.getNumShards() too.