I doubt using Redis as directory-storage will be very good. I'd expect it to have much more latency for reads and writes compared to any of lucene's own directories. And Lucene probably won't like it if another Lucene-instance changes that database.
It may be interesting as a result-level cache though, if you have a relatively large amount of repeated queries. With regards to RAMDirectory (and its successor the ByteBuffersDirectory), it works well enough for our setup: we run an in-memory copy of our regular sql database in an elastic search like setup to support very fast responses with a form of faceted search which would require relatively complex sql-statements (and many repeated ones). Lucene is only used for textual search in that system. We didn't want any trouble trying to sync whatever is on disk with the database and/or having to purchase relatively expensive storage in the servers. The total application uses about 6GB of RAM, of which somewhere between 1/2 and 1/3 is for the Lucene directories (about 20-30). We run an independent copy of that application on each of our 4 applications servers, so we can afford a relatively long startup time of the application. In all it only takes about 4-5 minutes to load all data and build in-memory lucene databases. Our largest Lucene directory is about 400MB, and RAMDirectory worked pretty good for this. We switched to ByteBuffersDirectory with 7.5, but I actually didn't see much performance improvements or savings in memory. If you do care about the rebuild time of your search engine, than just using Lucene's recommended database and not trying to add additional complexity with those in-memory databases is probably a good idea :) Best regards, Arjen On 2-12-2018 10:22, Joe MA wrote: > Greetings, > > Has anyone looked into using Redis or some other in-memory cache with Lucene? > It seems that ElasticSearch may do this. Are there advantages to doing this > versus, say, the RAMDirectory class? > > Thanks in advance, > J > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org > For additional commands, e-mail: java-user-h...@lucene.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
