Full Text Search: Fundamentals
Full Text Search (FTS) lets you create, manage, and query specially purposed indexes, defined on JSON documents within a Couchbase bucket.
Features of Full Text Search
Full Text Search provides extensive capabilities for natural-language querying. These include:
- Language-aware searching; allowing users to search for, say, the word beauties, and additionally obtain results for beauty and beautiful.
- Scoring of results, according to relevancy; allowing users to obtain result-sets that only contain documents awarded the highest scores. This keeps result-sets manageably small, even when the total number of documents returned is extremely large.
- Fast indexes, which support a wide range of possible text-searches.
Full Text Search is powered by Bleve, an open source search and indexing library written in Go. Full Text Search uses Bleve for the indexing of documents, and also makes available Bleve’s extensive range of query types. These include:
- Match, Match Phrase, Doc ID, and Prefix queries
- Conjunction, Disjunction, and Boolean field queries
- Numeric Range and Date Range queries
- Geospatial queries
- Query String queries, which employ a special syntax to express the details of each query (see Query String Query for information)
Full Text Search includes pre-built text analyzers for the following languages: Arabic, CJK characters (Chinese, Japanese, and Korean), English, French, Hindi, Italian, Kurdish, Persian, and Portuguese. Additional languages have been added to Couchbase Server 5.5.
Additionally, Full Text Search scores documents by means of Bleve’s industry standard tf-idf scoring, with query time boosting.
Authorization for Full Text Search
To access Full Text Search, users require appropriate roles. The role FTS Admin must therefore be assigned to those who intend to create indexes; and the role FTS Searcher to those who intend to perform searches. For information on creating users and assigning roles, see Authorization.