Hi there, I'm one of the developers of Jetpack's new Elasticsearch-powered Search feature in the Professional plan.

I want to make a quick comment on your discussion of algorithmic feeds:

Jetpack's Elasticsearch module only intercepts _searches_. It doesn't alter your home page feed at all. This is not for creating a Facebook-style feed (though that might be a fun thing to add in the future for bbPress and BuddyPress sites).

Elasticsearch isn't best for creating chronological feeds. Sorting chronologically isn't hard for MySQL, it actually is one of the things that a database like MySQL does best. Where Elasticsearch shines is when you search using a phrase to find the most relevant content for your query - so-called "needle in a haystack" search.

Elasticsearch can combine many factors, not just word frequency, when ranking results. It can search in language-aware ways for stemming, spell-correction and more. It can search nested document features like taxonomies at blazing speed. It can surface "aggregations" across results that let you drill down by any aspect of a document - date, rating, price, etc. with almost no performance cost. And, obviously, it can search vast amounts of content extremely quickly by distributing the search across hundreds of machines at once.

But the main thing I wanted to say is: there's a difference between a feed and search. Jetpack Search is focused on Searching, and we think this is a great example of where Jetpack can add value to your site that will never make it to Core because it requires specialized infrastructure that almost all hosting plans don't include.