Sunday, April 12, 2009

Lucene.Net Logical Index Structure

In the index file data are kept as Documents. Each document contains several fields that consist of name and value pairs. Therefore index file have several documents stored and each document contains several fields.

Fields are used to keep information in different ways in the indexed file. There are four types of field types.

They are listed in the below table with the description of the field type.

Field Type

Description

Keyword

Constructs a string value field that is not tokenized, but is indexed and stored. Therefore it is useful for non-text fields and for fields which we want to keep information as it is. Therefore name of the video file is keep in a this type of field

Text

Constructs a string value field that is tokenized, indexed and stored. Information in this type of field will return with hits. These types of fields are useful to keep content in a video frame.

UnIndexed

Constructs a string value field that is not tokenized nor indexed, but is stored in the index

UnStored

Constructs a string value field that is tokenized and indexed, but is not stored in the index



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