On Mon, Mar 26, 2012 at 4:55 PM, Thomas Mueller <[email protected]> wrote: > Hi, > >>I haven't looked at / tested JCR joins : I just can't imagine that is >>scales enough, but perhaps this is more related to my 'Lucene 1.4 >>experience' :) > > Lucene 1.4?
That's when I first used Lucene, don't worry :) However note, *many* of the current jackrabbit 2 search implementation designs still stem from the short comings of the early Lucene 1.4 version! For example that all properties are indexes in a single Lucene field, or that there is a hierarchy of Lucene indexes (there was no 'reopen' of an index reader back then) > > For Oak, joins should perform well (I guess with 'scale' you mean I meant the joins in jackrabbit 2 : They are implemented in Lucene afaik, and I cannot imagine those to perform very well for millions of nodes. However, I did not test them so I might be wrong For the current oak implementation, I cannot judge the performance of joins at all. With scale I indeed mean performance, but then specifically whether the performance scales. > 'perform'). Currently only nested loop joins are implemented (this is what > relational databases use most of the time). If this turns out to be a > problem, we might want to implement other join algorithms (block-nested > loop join, hash join, merge join). But first let's see if it really is a > problem. > >>I am not sure if it would be an issue for oak, but for jr 1 and 2, we >>build up jcr session keeping virtual node states in memory : This can >>grow too large, and it not easy to limit. > > OK I see. With "virtual nodes" I was thinking about temporary nodes that > only exist while iterating of the query result. But this is something I > will keep in mind. I'm sure we will find a good solution. > >>but I think it is all much easier if we >>expose faceting not over a node structure. Perhaps a row structure, >>where some 'row' do not have a backing jcr node? > > It's hard to say right now, I think we should postpone talking about the > implementation details until we have all the pieces and a good test case. Yes, agreed Regards Ard > > Regards, > Thomas > -- Amsterdam - Oosteinde 11, 1017 WT Amsterdam Boston - 1 Broadway, Cambridge, MA 02142 US +1 877 414 4776 (toll free) Europe +31(0)20 522 4466 www.onehippo.com
