Which index type is typically used for full-text search?

Which index type is typically used for full-text search?

• A. Hash
• B. Geospatial
• C. Inverted
• D. B-tree

Answer: (C)

Full-text search relies on an inverted index. This structure builds a dictionary of terms found in the text and, for each term, a list of documents (often with position information) where that term appears. With this, a query like “term1 term2” can quickly fetch documents containing one or more of the terms and then intersect or rank those candidate documents. The position data also enables efficient phrase and proximity searches, and the index supports ranking by how common or rare a term is across the collection. Other index types aren’t optimized for this use case. A hash index maps a single exact key to a value, which isn’t helpful for locating all documents containing a given word or for multi-term queries. A B-tree is excellent for ordered, range, and exact lookups but isn’t designed to efficiently handle the many-to-many term-to-document mappings used in full-text search. A geospatial index organizes data by location, which is unrelated to text search.

Full-text search relies on an inverted index. This structure builds a dictionary of terms found in the text and, for each term, a list of documents (often with position information) where that term appears. With this, a query like “term1 term2” can quickly fetch documents containing one or more of the terms and then intersect or rank those candidate documents. The position data also enables efficient phrase and proximity searches, and the index supports ranking by how common or rare a term is across the collection.

Other index types aren’t optimized for this use case. A hash index maps a single exact key to a value, which isn’t helpful for locating all documents containing a given word or for multi-term queries. A B-tree is excellent for ordered, range, and exact lookups but isn’t designed to efficiently handle the many-to-many term-to-document mappings used in full-text search. A geospatial index organizes data by location, which is unrelated to text search.