lucene-相关概念与定义

 

• 原文： http://wiki.apache.org/lucene-java/ConceptsAndDefinitions
• 导航：Lucene-java Wiki-》1 Overview-》1.1 Informational-》 1.1.2 ConceptsAndDefinitions
• 注意：“ 红色 ”，表示不知道、不确定怎么翻译。  “ 蓝色”自己的描述。

这里主要描述了一些Lucene的相关概念和定义

 

定义

 

Analyzer  - 用于在分析文本，英语和拉丁语系通常用StandardAnalyzer 。编制索引的文本Lucene的类。大多数应用程序可以使用英语和拉丁语的语言StandardAnalyzer。

 

Payloads(有效载荷) - payload 是一个字节数组（array of bytes），用于存储term的位置。

 

Snowball Stemmers(雪球词干分析器 ) --Snowball Stemmers是lucene引入的词干分析器之一。 更多信息请参看 nowball website 。

 

Stemmer （词干分析器） - 以下解释来自于维基：“这种算法用来降低干扰词、同义词的影响……，以用于降低索引大小……” 。这一段原文如下：

 

 

"A stemming algorithm, or stemmer, is a computer program or algorithm for reducing inflected (or sometimes derived) words to their stem, base or root form — generally a written word form." Stemmers are often used to reduce the search space and index size. Often times a user searching for "widgets" is interested in documents that contain the term "widget".

 

 

 

核心类

 

Document

A Lucene Document is a record in the index. A Document has a list of fields; each field has a name and a textual value.

 

Term

A Term is Lucene's unit of indexing. In western languages, a Term is often a word.

 

TermEnum

TermEnum 通常用于统计某个field中的term个数，但不考虑这些term出现在哪个document中。

 

一些查询子类就是通过对比terms 来实现查询的，例如： WildcardQuery,PrefixQuery, RangeQuery.

 

 

 

原文

TermEnum is used to enumerate all terms in the index for a given field, regardless of which documents the terms occur in (or where they occur).

Some query subclasses are implemented by enumerating terms that match a pattern, and building a large OR query from the enumeration. E.g. WildcardQuery,PrefixQuery, RangeQuery.

See LuceneFAQ, How do I retrieve all the values of a particular field that exists within an index, across all documents? which also includes sample code.

 

 

 

TermDocs

不像TermEnum (see above), TermDocs 通常用于确定哪些文档包括给定的Term。另外，TermDocs 也提供了term 在文档中出现的频率。

 

TermFreqVector

A TermFreqVector (aka Term Frequency Vector or just Term Vector) is a data structure containing a given Document's term and frequency information and can be retrieved from the IndexReader only when Term Vectors are stored during indexing.

 

TermFreqVector 是一个包含 given Document's term 和**的数据结构。

 

 原文

A TermFreqVector (aka Term Frequency Vector or just Term Vector) is a data structure containing a given Document's term and frequency information and can be retrieved from the IndexReader only when Term Vectors are stored during indexing.

 

Directory

 

IndexReader

 

IndexSearcher