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Instant MapReduce Patterns – Hadoop Essentials How-to by Srinath Perera

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Simple search with MapReduce (Intermediate)

Text search is one of the first use cases for MapReduce, and according to Google, they built MapReduce as the programming model for text processing related to their search platform.

Search is generally implemented with an inverted index. An inverted index is a mapping of words to the data items that includes that word. Given a search query, we find all documents that have the words in the query. One of the complexities of web search is that there are too many results and we only need to show important queries. However, ranking the documents based on their importance is out of the scope of this discussion.

This recipe explains how to build a simple inverted index based search using MapReduce.

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