# Information retrieval

> Finding a recorded item that answers a need. Search engines, relevance, and the structure of the data sit under this subject. It is the field I study.

## Within this subject

- [Search engines](https://oppority.com/topics/search-engines.md): The libraries and servers that keep an index and answer a query. The names under this subject are systems I have read and worked with.
- [Relevance](https://oppority.com/topics/relevance.md): Whether the result a person receives is one they can act on. Hybrid ranking, similarity, and the structure of the data sit under this subject.

## Work

- [Public search at country scale](https://oppority.com/work/public-search.md): Search a citizen can use: a polling place, a beneficiary record, found in hundreds of millions of rows.
- [Concept search before vectors were the default](https://oppority.com/work/concept-search.md): A books-and-journals search that let people explore by concepts, built in 2018 from phrases and similarity, not from a vector database.
- [One catalog, many storefronts](https://oppority.com/work/retail-search.md): Product search, autosuggest, filters, and per-field similarity for an omnichannel retailer: web, marketplace, and stores.
- [Return one record, not a list](https://oppority.com/work/one-best-record.md): From millions of candidates that share an organisation's name and address, return the single best record.
- [A move that kept the answers](https://oppority.com/work/platform-move.md): A production move from self-managed Apache Solr to managed OpenSearch, checked by whether the top results still agreed.
- [The team's output](https://oppority.com/work/search-team.md): Leading a search engineering group while staying close enough to the system to tell a relevance question from an operations question.
- [A new engine, tried on a laptop](https://oppority.com/work/reading-luxir.md): A hands-on reading of Luxir, a new hybrid search engine, run from a Mac or Windows laptop without compiling C++.

## Notes

- [Run Luxir on a Mac or Windows laptop (no Linux, no C++)](https://oppority.com/writing/run-luxir-on-a-mac-or-windows-laptop.md)