Inverted Index
An inverted index maps each term to the list of documents containing it; the core data structure of full-text search engines.
Purpose
To understand full-text search principles and design efficient text retrieval systems.
Mechanism
After tokenization, each term gets a posting list (document ID + term frequency + positions). Queries merge posting lists (AND/OR) and rank by TF-IDF/BM25. Compression (delta encoding + VByte) reduces space.
Use cases
- Full-text search design
- Search engine internals
- Document retrieval
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