NOTE
Inverted Index
Mapping terms to document postings for efficient full-text search.
This is a historical learning note and may contain outdated or incomplete understanding.
An inverted index maps a term to a postings list describing documents containing that term, optionally with term frequency, positions, payloads, or other scoring/search metadata.
Text is analyzed/tokenized before indexing, so analysis rules are part of the search schema. Query processing intersects/unions/advances postings rather than scanning every document.
Search engines combine inverted indexes with additional structures for sorting, aggregations, stored fields, and retrieval.