faceting on nested documents in solr 5.3 is possible with "JSON Facet API" http://yonik.com/solr-nested-objects/
I use Solr version 4.8 therefore I cannot use "JSON Facet API".
I have parent and children docs by using "Block Join Query": https://cwiki.apache.org/confluence/display/solr/Other+Parsers#OtherParsers-BlockJoinQueryParsers
As you can see in the document, I need to use 'Block Join Children Query Parser' to get children docs: q={!child of="content_type:parentDocument"}title:lucene
and use "Block Join Parent Query Parser" to get parent docs: q={!parent which="content_type:parentDocument"}comments:SolrCloud
I want to use "Block Join Parent Query Parser" and have children fields as facet filter.
In other words, user use search phrase to search parent documents and use children fields as facet filters to filter docs.
Is there any way to do this?