ElasticSearch use an inverted index structure that is suitable for fast full-text search, inverted index consists of a list of all documents not repeat the word, for each word, there is a list of documents containing it, can improve the documentation search speed. If the documents are as follows:
The establishment of inverted index as follows:
Inverted index table to record the frequency, ie the number of times a word appears in a document, as shown below, "Mathematics" word document 3 appears twice in the document number.
An inverted index table may also recording position information word appears as (1, <11>, 1), (3, <3,9>, 2) represent the word id appears as word 1 1, the position is 11 the word id appeared twice as word 3, position 3 and 9, respectively.