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Reranking

Reranking can help improve the quality of AI Search results by reordering retrieved documents based on semantic relevance to the user's query. It applies a secondary model after retrieval to rerank the top results before they are returned.

How it works

By default, reranking is disabled for all AI Search instances. You can enable it during creation or later from the settings page.

When enabled, AI Search will:

  1. Retrieve a set of relevant results from your index, constrained by your max_num_results and score_threshold parameters.
  2. Pass those results through a reranking model.
  3. Return the reranked results, which the text generation model can use for answer generation.

Reranking helps improve accuracy, especially for large or noisy datasets where vector similarity alone may not produce the optimal ordering.

Configuration

When you make a /search or /chat/completions request using the Workers binding or REST API, you can enable or disable reranking per request and specify the reranking model.

TypeScript
const instance = env.AI_SEARCH.get("my-instance");


const results = await instance.search({
  messages: [{ role: "user", content: "What is Cloudflare?" }],
  ai_search_options: {
    reranking: {
      enabled: true,
      model: "@cf/baai/bge-reranker-base",
    },
  },
});

Considerations

Adding reranking will include an additional step to the query request, as a result, there may be an increase in the latency of the request.