Hello, I recently ran into a problem that documents disappear from our collections when I split a shard. To be specific, they are not copied to new shards made by the split command.
After some debugging I figured out that it is related to router.field we have defined for our collections and that field happens to be not indexed. In this case ShardSplitter ( https://github.com/apache/lucene-solr/blob/releases/lucene-solr/7.5.0/solr/core/src/java/org/apache/solr/update/SolrIndexSplitter.java#L553) here gets null terms, empty docSet is returned and documents are not copied. This behavior is not mentioned in Collection API documentation for router.field ( https://lucene.apache.org/solr/guide/8_6/collection-management.html#create) or in split shard documentation ( https://lucene.apache.org/solr/guide/8_6/shard-management.html#splitshard). This applies at least for solr 7.5. Is this a known problem? I would think that split operation should fail in this case and at least by minimum it should be mentioned in documentation. What do you think? Br, Niko Himanen
