Lucene
An open-source full-text search engine library from Apache that uses inverted indexes and an immutable segment architecture, and serves as the foundation for search systems such as Elasticsearch and Solr.
Core Facts
Timeline (last 90 days)
Modern search engines (such as Lucene) split the index into multiple immutable segments, each segment being a set of small inverted index files, and at query time search each segment in parallel and then merge the results.
FST (Finite State Transducer) is the core technology behind high-performance Term Dictionaries in search engines such as Lucene, capable of associating output values while simultaneously performing prefix matching and weight retrieval.
FST (Finite State Transducer) is the core technology behind the high-performance Term Dictionary implementation in the Lucene search engine.
Lucene's empirical data shows that FST can save more than 90% of memory compared to HashMap.
Memory-mapped files (mmap) are an OS-provided mechanism that maps file contents directly into a process's address space, and storage engines such as Lucene and RocksDB make extensive use of mmap.
All Facts (6)
BM25 remains the default ranking algorithm for mainstream search engines such as Elasticsearch and Lucene.
75%UnverifiedModern search engines (such as Lucene) split the index into multiple immutable segments, each segment being a set of small inverted index files, and at query time search each segment in parallel and then merge the results.
50%UnverifiedFST (Finite State Transducer) is the core technology behind high-performance Term Dictionaries in search engines such as Lucene, capable of associating output values while simultaneously performing prefix matching and weight retrieval.
50%UnverifiedFST (Finite State Transducer) is the core technology behind the high-performance Term Dictionary implementation in the Lucene search engine.
50%UnverifiedLucene's empirical data shows that FST can save more than 90% of memory compared to HashMap.
50%UnverifiedMemory-mapped files (mmap) are an OS-provided mechanism that maps file contents directly into a process's address space, and storage engines such as Lucene and RocksDB make extensive use of mmap.
50%