According to Solr wiki https://wiki.apache.org/solr/SolrCaching
filterCache stores unordered sets of document IDs that match the key
queryResultCache stores ordered sets of document IDs
What is the document id being referred to here? What is its size? Is it a boolean bit vector with 1/0 for all documents present in the collection, such that its size is equivalent to total docs * 1 bit?
Also is there any way to get the exact size of each cache in bytes?