Keyword search

Enable keyword search to match chunks that contain your query terms exactly. For an overview of search modes, refer to Search modes.

Enable keyword search

Set index_method.keyword to true when creating or updating an instance. You can use keyword search on its own or alongside vector search for hybrid search.

Field	Type	Default	Description
`vector`	boolean	`true`	Enable vector (semantic) search.
`keyword`	boolean	`false`	Enable keyword (BM25) search.

At least one of vector or keyword must be true. Changing index_method triggers a full reindex of your content.

const instance = await env.AI_SEARCH.create({
  id: "my-instance",
  index_method: {
    vector: false,
    keyword: true,
  },
});

Keyword tokenizer

The keyword_tokenizer field (inside indexing_options) controls how text is split into tokens. Changing this triggers a full reindex.

Value	Default	Description
`porter`	Yes	Applies Porter stemming. "running" matches "run." Best for natural language.
`trigram`	No	Overlapping 3-character windows. "config" matches "configuration." Best for code.

Keyword match mode

The keyword_match_mode field (inside retrieval_options) controls how multiple query terms are combined.

Value	Default	Description
`and`	Yes	All query terms must appear. Higher precision, fewer results.
`or`	No	Any query term can match. Higher recall, more results.

You can override keyword_match_mode per request:

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

const results = await instance.search({
  messages: [{ role: "user", content: "What is Cloudflare?" }],
  ai_search_options: {
    retrieval: {
      keyword_match_mode: "or",
    },
  },
});

Limits

Instances with keyword search enabled support up to 500,000 files per instance on the Workers Paid tier, compared to 1,000,000 for vector-only instances. Refer to Limits and pricing for the full list of limits.