Searching for posts by a given user with a given tag, the default sorting is by "relevance", whatever that is. Looks pretty random to me. Relevance to what? How is relevance measured, and why is it the default?

1 Answer 1


SE uses elasticsearch.

This is what elasticsearch has to say about relevance:

  • Uses TF/IDF, or Term Frequency/Inverse Document Frequency algorithm
  • Computes a relevance score, based on the query
  • How that score is calculated depends on the type of query clause — different query clauses are used for different purposes: a fuzzy query might determine the _score by calculating how similar the spelling of the found word is to the original search term, a terms query would incorporate the percentage of terms that were found

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