NHibernate Search Clustered Lucene Index

Question

We are using NHibernate Search in an application which is going to be clustered. I have been reading up on the approaches for maintaining separate collections, in particular the master/slave configuration and I was wondering how to go about implementing it using MSMQ if indeed there is an implementation for this at this time. The JMS implementation (as described in NHibernate Search in Action) seems a little daunting to me, especially as we are using a .NET environment.

Alternatively, I'm open to suggestions with regard to instantiating local RAMDirectories for the lucene collections. I know that Lucene can build a RAMDir from a FSDir and I know how to initialise an NHibernate app with a blank RAMDir but I'm getting a little lost when it comes to initialising an app with a RAMDir from an existing (network shared) FSDir.

Or indeed any other approaches.

Cheers, Steve

Answer 1

I have actually recently came across this very problem. Primarily because we shared index over several webapps, for realtime updates to the indexes. However, we suffered from index corruption and couldn't really figure out why, aswell as the fact that it wouldn't work in a clustered enviroment.

My approach was this: using a service that schematically indexed new entities at very frequent intervals, aswell as reindexing everything at certain timeintervals. I also run an optimize automatically, since NHSearch doesn't seem to support auto-optimize yet.

At application start, I index everything into a RAMDirectoryProvider.

The choice you make depends highly on the data that you want to index and how sensitive you are to delays in that data, aswell as how frequent it changes. In my case, it was to allow textsearches amongst product-data for a website, so any delay was fine with me.

I did some brief research about Master-Slave providers, however I think I felt that NHSearch is rather imature as opposed to the original Java-implementation.

For me, an optimal solution would be to have a Master-Master provider, that would cross-apply all updates to the index on all nodes. I haven't research how much work it would be to write a DirectoryProvider myself, but that would be an option but much effort aswell.