Similarity cache default drops from 30 days to 48 hours

AI Search now gives you more control over similarity cache freshness. Similarity cache helps reduce latency and inference cost by reusing responses for semantically similar queries.

With these updates, you can choose how long responses are eligible for reuse and clear cached responses when they may be stale.

Cache duration now defaults to 48 hours

Previously, AI Search cached responses for a fixed duration of 30 days. Cached responses now use the instance's cache_ttl setting, and the default is 48 hours.

You can set cache_ttl when creating or updating an instance to choose a cache duration from 10 minutes to 6 days.

Use a shorter TTL when your source content changes frequently and freshness is more important. Use a longer TTL when your content is stable and you want more cache reuse.

For example, set cache_ttl to 518400 to retain cached responses for 6 days:

<div><div><span>{</span></div></div><div><div><span>  </span><span>"</span><span>cache_ttl</span><span>"</span><span>:</span><span> </span><span>518400</span></div></div><div><div><span>}</span></div></div>

Purge cached responses

You can also purge all cached responses for an instance on demand. Purging cached responses does not delete indexed content or source files.

It prevents AI Search from reusing previous cached responses, so subsequent similar queries generate fresh answers and repopulate the cache.

<div><div><span>curl</span><span> </span><span>-X</span><span> </span><span>POST</span><span> </span><span>"https://api.cloudflare.com/client/v4/accounts/</span><span>$ACCOUNT_ID</span><span>/ai-search/instances/</span><span>$INSTANCE_NAME</span><span>/purge_cache"</span><span> </span><span>\</span></div></div><div><div><span>  </span><span>-H</span><span> </span><span>"Authorization: Bearer </span><span>$CLOUDFLARE_API_TOKEN</span><span>"</span></div></div>

You can also purge cached responses from the instance settings page in the Cloudflare dashboard.

Refer to similarity cache for the full list of supported cache_ttl values and more details about cache behavior.