Signature files
Encyclopedia
Signature files is a technique applied for document retrieval
Document retrieval
Document retrieval is defined as the matching of some stated user query against a set of free-text records. These records could be any type of mainly unstructured text, such as newspaper articles, real estate records or paragraphs in a manual...

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The idea behind Signature files is to create a quick and dirty filter that will keep all the documents that match to the query and hopefully a few ones that do not.
The way this is done is by creating for each file a signature, typically a hash coded version. One method is superimposed coding.
A post-processing step is done to discard the false alarms.
Since in most cases this structure is inferior to inverted files in terms of speed, size and functionality, it is not used widely. However, with proper parameters it can beat the inverted files in certain environments.
The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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