Sparse indexes only contain entries for documents that have the indexedfield.
稀疏索引只包含文档的索引字段的条目。
2
The content in a field can be indexed or just stored as is for use by an application.
可以为字段中的内容建立索引,或者原样储存供应用程序使用。
3
A field is made up of the actual content to be indexed or stored plus metadata telling Lucene how to handle that content and a boost value indicating that field's importance.