Writing and Querying MapReduce Views in CouchDB

Limitations of MapReduce

While very powerful and applicable to a wide variety of problems, MapReduce is not the answer to every problem. The index generated in the Map step is one dimensional, and the Reduce step must not generate a large amount of data or there will be a serious performance degradation. For example, CouchDB’s MapReduce may not be a good fit for full-text indexing or ad hoc searching. This is a problem better suited for a tool such as Lucene. Fortunately, you can integrate CouchDB with Lucene using couchdb-lucene, or by integrating ElasticSearch and CouchDB. Indexing and searching geospatial data is also not easily done within CouchDB, but is possible using a CouchDB extension called GeoCouch.