![]() The Lucene query language allows the user to specify which field(s) to search on, which fields to give more weight to (boosting), the ability to perform boolean queries (AND, OR, NOT) and other functionality. Lucene has its own mini-language for performing searches. It involves creating a Query (usually via a QueryParser) and handing this Query to an IndexSearcher, which returns a list of Hits. Searching requires an index to have already been built. Following diagram illustrates the process and its. Indexing in Lucene thus involves creating Documents comprising of one or more Fields, and adding these Documents to an IndexWriter. The process of searching is one of the core functionalities provided by Lucene. In the case of a title Field, the field name is title and the value is the title of that content item. For example, a Field commonly found in applications is title. It is a technology suitable for nearly any application. For example, if you're creating a Lucene index of a database table of users, then each user would be represented in the index as a Lucene Document.Ī Document consists of one or more Fields. Apache Lucene is a high-performance, full-featured search engine library written entirely in Java. Indexing involves adding Documents to an IndexWriter, and searching involves retrieving Documents from an index via an IndexSearcher.Ī Lucene Document doesn't necessarily have to be a document in the common English usage of the word. In Lucene, a Document is the unit of search and index.Īn index consists of one or more Documents. However, some cases may require improvements in how documents are scored. For most business requirements, a default configuration of Elasticsearch will be sufficient. This type of index is called an inverted index, because it inverts a page-centric data structure (page->words) to a keyword-centric data structure (word->pages). Apache Lucene is the heart of Elasticsearch and provides an interface which helps with abstracting the complexity and algorithms behind the scenes. This would be the equivalent of retrieving pages in a book related to a keyword by searching the index at the back of a book, as opposed to searching the words in each page of the book. ![]() A Phrase is a group of words surrounded by double quotes such as welcome lucene. A Single Term is a single word such as test or sample. Terms are of two types: 1.Single Terms and 2.Phrases. ![]() A query is broken up into terms and operators. Lucene is the index used by SOLR which provides tuning and architectures more similar to a GSA (including result retrievel over HTTP (s)) GSA let's you bias result sets based on meta-data, date and URL patterns. Lucene is able to achieve fast search responses because, instead of searching the text directly, it searches an index instead. Lucene has a custom query syntax for querying its indexes. The content you add to Lucene can be from various sources, like a SQL/NoSQL database, a filesystem, or even from websites. It then allows you to perform queries on this index, returning results ranked by either the relevance to the query or sorted by an arbitrary field such as a document's last modified date. It does so by adding content to a full-text index. Lucene is a full-text search library in Java which makes it easy to add search functionality to an application or website.
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