An inverted index, also known as postings list, postings file, or inverted file, is a database index that stores a mapping from content, such as words or numbers, to their locations in a table, a document, or a set of documents.

Trade off

  • Large storage overhead and high maintenance costs on update, delete, and insert operations
  • Retrieval of records occurs in the order in which they appear in the inverted lists, rather than in decreasing order of expected usefulness