Mike, I agree that it's not absolutely necessary to enforce children not being their own parent. I was just trying to describe the current implementation, and why you were seeing exceptions.
The difference is mostly philosophical. The advantage of the current approach (in my opinion) is that it the BlockJoin mechanic has a lot of terrible edge cases if used naively, and enforcing "child can't be its own parent" can help catch quite a few of them. I had a discussion on this list on the same topic, which might be useful: Re: including self-joins in parent/child queries <http://mail-archives.apache.org/mod_mbox/lucene-java-user/201412.mbox/%3ccaasl1-_ppmcnq3apjjfbt3adb4pgaspve-8o5r9gv5kldpf...@mail.gmail.com%3E> -Greg On Wed, Jan 21, 2015 at 7:59 PM, Michael Sokolov < msoko...@safaribooksonline.com> wrote: > On 1/21/2015 6:59 PM, Gregory Dearing wrote: > >> Jim, >> >> I think you hit the nail on the head... that's not what BlockJoinQueries >> do. >> >> If you're wanting to search for children and join to their parents... then >> use ToParentBlockJoinQuery, with a query that matches the set of children >> and a filter that matches the set of parents. >> >> If you're searching for parents, then joining to their children... then >> use >> ToChildBlockJoinQuery, with a query that matches the set of parents and a >> filter that matches the set of children. >> >> When you add related documents to the index (via addDocuments), make that >> children are added before their parents. >> >> The reason all the above is necessary is that it makes it possible to have >> a nested hierarchy of relationships (ie. Parents have Children, which have >> Children of their own). You need a query to indicate which part of the >> hierarchy you're starting from, and a filter indicating which part of the >> hierarchy you're joining to. >> >> Also, you will always get an exception if your query and your filter both >> match the same document. A child can't be its own parent. >> > That's true for the existing implementation, but seems unnecessary from > what I can tell. See https://github.com/safarijv/ > ifpress-solr-plugin/blob/master/src/main/java/com/ > ifactory/press/db/solr/search/SafariBlockJoinQuery.java for a variant > that allows a child to be its own parent. > > -Mike > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > >
