MarginaliaSearch/code/features-index
Viktor Lofgren 3101b74580 (index) Move to a lexicon-free index design
This is a system-wide change.  The index used to have a lexicon, mapping words to wordIds using a large in-memory hash table.   This made index-construction easier, but it
also added a fairly significant RAM penalty to both the index service and the loader.

The new design moves to 64 bit word identifiers calculated using the murmur hash of the keyword, and an index construction based on merging smaller indices.

It also became necessary half-way through to upgrade guice as its error reporting wasn't *quite* compatible with JDK20.
2023-08-28 14:02:23 +02:00
..
domain-ranking (index) Move to a lexicon-free index design 2023-08-28 14:02:23 +02:00
index-forward (index) Move to a lexicon-free index design 2023-08-28 14:02:23 +02:00
index-journal (index) Move to a lexicon-free index design 2023-08-28 14:02:23 +02:00
index-query (index) Move to a lexicon-free index design 2023-08-28 14:02:23 +02:00
index-reverse (index) Move to a lexicon-free index design 2023-08-28 14:02:23 +02:00
readme.md Update readme.md 2023-03-20 16:27:37 +01:00

Index

These are components that offer functionality for the index-service.

Indexes

There are two indexes with accompanying tools for constructing them.

  • index-reverse is code for word->document indexes. There are two such indexes, one containing only document-word pairs that are flagged as important, e.g. the word appears in the title or has a high TF-IDF. This allows good results to be discovered quickly without having to sift through ten thousand bad ones first.

  • index-forward is the document->word index containing metadata about each word, such as its position. It is used after identifying candidate search results via the reverse index to fetch metadata and rank the results.

These indices rely heavily on the libraries/btree and libraries/array components.

Algorithms

Libraries

  • index-query contains structures for evaluating search queries.
  • index-journal contains tools for writing and reading index data.
  • lexicon contains a mapping between words' string representation and an unique integer identifier.