Lucene.net

[andrewyakonyuk]

Tips for integrating Lucene.net into app

[andrewyakonyuk]

Official FAQ

• Open the IndexReader with readOnly=true. This makes a big difference when multiple threads are sharing the same reader, as it removes certain sources of thread contention.
• Share a single IndexSearcher across queries and across threads in your application.
• Consider using filters. It can be much more efficient to restrict results to a part of the index using a cached bit set filter rather than using a query clause. This is especially true for restrictions that match a great number of documents of a large index. Filters are typically used to restrict the results to a category but could in many cases be used to replace any query clause. One difference between using a Query and a Filter is that the Query has an impact on the score while a Filter does not. (note: Basically, if you have one or two conditions that need to apply to almost every search (e.g. hide all documents which are "high security") then you might want to look into filters. Otherwise, just doing normal queries should perform better, since filters can take up a lot of memory.)

Some additional tips:

• Choose the most appropriate locking mechanism.
• Use the SetRAMBufferSizeMB to reduce the disk I/O overhead when writing the index.
• Don't over use the SetMaxBufferedDocs property.
• Use the Search hits (TopDocs and ScoreDoc[]) object to retrieve the index search results.
• Index writing is an expensive operation, so use it sparingly.
• Know the data that you will be indexing as some data types (I.E., dates) can be difficult to search on if they are not stored consistently.
• There is no UPDATE functionality within Lucene so a document needs to be deleted and re-added.

Source

[andrewyakonyuk]

Syncing Lucene.net indexes across multiple app servers

Available options:

• Using one server for indexing and having the 2nd server access the indexes via SMB
• Indexing to both servers, essentially writing every index twice
• Using SOLR or KATTA to wrap access to the indexes
• Using Lucene.net DistributedSearch contrib module

In general way, the most appropriate solution is storing copies of indexes on the both servers. But question is: what to do in case of multiple instances of the same app on the single server? Is the app needed create his own copy of indexes, because we cannot have two writers writing to the same location.

Multiple or single index in Lucene?

The app contains a multiple types of the content (article, audio, events, places etc) with different sets of fields. I am looking for best approach to store these types and searching them together. The most voted answer recommends to use the single index, but I am not entirely sure about that.

[andrewyakonyuk]

Lucene TermQuery and QueryParser

When you use QueryParser, it uses analyzer which does the same sequence of actions as when during the indexing (tokenization, lowercasing, stopwords, etc.).

When you use raw TermQuery, you need to do all these steps yourself.

I guess your analyzer does something special about Properties.LUCENE_APPARTMENT_ADDRESS and you are not when passing the address to TermQuery hence the search results discrepancy.