Situations to prefer Apache Lucene over Solr?

Question

There are several advantages to use Solr 1.4 (out-of-the-box facetting search, grouping, replication, http administration vs. luke, ...).

Even if I embed a search-functionality in my Java application I could use SolrJ to avoid the HTTP trade-off when using Solr. Is SolrJ recommended at all?

So, when would you recommend to use "pure-Lucene"? Does it have a better performance or requires less RAM? Is it better unit-testable?

PS: I am aware of this question.

Answer 1

If you want to completely embed your search functionality within your application and do not want to maintain a separate process like Solr, using Lucene is probably preferable. Per example, a desktop application might need some search functionality (like the Eclipse IDE that uses Lucene for searching its documentation). You probably don't want this kind of application to launch a heavy process like Solr.

Answer 2

If you have a web application, use Solr - I've tried integrating both, and Solr is easier. Otherwise, if you don't need Solr's features (the one that comes to mind as being most important is faceted search), then use Lucene.

Answer 3

Here is one situation where I have to use Lucene.

Given a set of documents, find out the most common terms in them.

Here, I need to access term vectors of each document (using low-level APIs of TermVectorMapper). With Lucene it's quite easy.

Another use case is for very specialized ordering of search results. For exmaple, I want a search for an author name (who has writen multiple books) to result into one book from each store in the first 10 results. In this case, I will find results from each book store and to show final results I will pick one result from each book store. Here you are essentially doing multiple searches to generate final results. Having access to low-level APIs of lucene definitely helps.

One more reason to go for Lucene was to get new goodies ASAP. This no longer is true as both of them have been merged and there will be synchronous releases.

Answer 4

You need to use Lucene,

• To have more control
• You cannot depend on any Web server
• To use termvector, termdocs etc
• You could easily extend to have your own Analyzer

You need to use Solr,

• To index and search docs easily by writting few code
• Solr is a standalone App and it takes care most of the stuff like optimizing,warmup the reader etc..
• Solr could be extended to multiple nodes
• To use facet

If you are developing your client in Java and want to use Solr then i would advise to use SolrJ as it is easy and you don't need to care about HTTP stuff. I use Solr using SolrJ in my project www.findbestopensource.com

Answer 5

I'm surprised nobody mentioned NRT - Near Real Time search, available with Lucene, but not with Solr (yet).