dovecot - Feb 2017 - Index queue

Hi,

can i, somehow, list mailboxes which are to be indexed by  
indexer-worker (=index queue?) ? How can i know what part of all  
mailboxes was indexed so far? Are there any statistics about Solr data  
dir size based on emails amount? For example, we have about 5TB of  
emails, what should i except about index size in Solr?

Thank you.

azur