I'm quite busy trying to get the latest (dev) Apache_Solr module to work with our complex multi site setup and it all went fine, until we had to import an huge phpbb2 forum (28k topics, near 1 million comments - some topic has thousands of comments).
Now I'm puzzled: which route should I go through? Does anyone has succesfully implemented something like that?
From the top of my mind, I'd consider each comment as a separate document to feed SOLR with, with a rightly cooked "indexer" script that will extract them AND the topic, of course (first the topics, then the comments).
Every problem will then be delegated to the template.php file and associated tpls, where I'll get each result, test if it is a comment or a topic, and if it's a comment load the relevant topic to show it alongside the comment itself...
Issues with this approach:
1. How one would consider a comment like a "document", with a bogus $nid?
2. How could I get back the parent topic of a comment, directly from SOLR schema?
Pondering... in the meanwhile, if anyone has an idea I'll be pleased to listen :)