Whats new in Lucene / Solr 4.0
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The release 4.0 is one of the important milestone for Lucene and Solr. It has lot of new features and performance important. Few important ones are highliggted in this article.
- ColumnStrideFields: DocValues are stored on a per-document basis where each documents field can hold exactly one value of a given type.
- Facet search, this feature was already available in Solr. It is now integrated to Lucene.
- With flexible indexing it is now possible for an application to create its own postings codec, to alter how fields, terms, docs and positions are encoded into the index.
- Added a variety of different relevance ranking systems to Lucene.
- Added a Codec implementation that works with append-only filesystems (such as e.g. Hadoop DFS).
- Added DirectSpellChecker, which retrieves correction candidates directly from the term dictionary using levenshtein automata.
- Indexed terms are no longer UTF-16 char sequences, instead terms can be any binary value encoded as byte arrays. By default, text terms are now encoded as UTF-8 bytes.
- Substantially faster performance when using a Filter during searching.
- FuzzyQuery is 100-200 times faster than in past releases.
- Added index statistics such as the number of tokens for a term or field, number of postings for a field, and number of documents with a posting for a field.
- Added RegexpQuery support to contrib/queryparser.
Solr 4.0-alpha includes more NoSQL features for those using Solr as a primary data store.
- Distributed indexing designed from the ground up for near real-time (NRT) and NoSQL features such as realtime-get, optimistic locking, and durable updates.
- High availability with no single points of failure.
- Apache Zookeeper integration for distributed coordination and cluster metadata and configuration storage.
- Updates sent to any node in the cluster and are automatically forwarded to the correct shard and replicated to multiple nodes for redundancy.
- Queries sent to any node automatically perform a full distributed search across the cluster with load balancing and fail-over.
- A transaction log ensures that even uncommitted documents are never lost.
- Real-time Get – The ability to quickly retrieve the latest version of a document, without the need to commit or open a new searcher.
- Atomic updates - the ability to add, remove, change, and increment fields of an existing document without having to send in the complete document again.
- Pivot Faceting – Multi-level or hierarchical faceting where the top constraints for one field are found for each top constraint of a different field.
- Pseudo-Join functionality – The ability to select a set of documents based on their relationship to a second set of documents.
- A brand new web admin interface, including support for SolrCloud.