Jetpack 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 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. To obtain results that include unpublished content, the query must enable an authentication mode.
For advanced use, some configuration is necessary to define which post types, taxonomies, etcetera to index, or which items should not be indexed. Also, for certain use cases that do not fit the default search results, some customization of the search queries may be needed, and can be accomplished by filtering the search requests to amend the Elasticsearch queries.