Jetpack Instant Search is a paid upgrade to the Jetpack plugin, bringing an improved search experience to self-hosted or WordPress.com-hosted WordPress sites. It uses Elasticsearch to provide this service. Jetpack handles the Elasticsearch indexing and searching described earlier, typically without any need for a site owner to add custom code.
For sites that are not hosted on WordPress.com (including WordPress VIP sites) Jetpack Instant Search will sync content changes to a private cache site located within Automattic’s data centers, and uses that cached copy to perform indexing. When search queries are performed, the database query is sent to a public endpoint which only returns results for publicly available data.