http://senseidb.com/ is another alternative that I work on used for search at LinkedIn. It's API compatible with Elasticsearch.

And if you want an actually good search product there is always SphinxSearch.

Last I checked, Sphinx had a huge design flaw in that it indexed directly from an SQL database. In other words, your Sphinx configuration not only needs to have read access to the database, it needs to contain the required SQL queries.

This tightly couples Sphinx to your application and your schema, and creates serious issues for your ops team since every app change potentially needs to modify the Sphinx config. It gets particularly hairy when you want to host multiple applications using a single Sphinx daemon.

We started out with Sphinx for our apps but quickly discarded it in favour of ElasticSearch, a much more elegant and orthogonal piece of software.

That's not true, you can pipe in data from any source:

http://sphinxsearch.com/docs/2.0.4/xmlpipe2.html

Also sphinx as real-time indexes.

You send data to sphinx (when you update it), and its indexed right away.

The original disk-indexes (updated by a batch process is still available)

I always find sphinx limiting. For example, I can add a single doc to the index, I have to run a full re-index.

Also, I can't programmatically get a list of all "words" in the index with their frequency and the inverse dod freq, etc. With anything lucene based this kind of thing is really easy.

+1 on this. I really liked Sphinx until I started inserting records...

Why wouldn't you consider ElasticSearch to be an "actually good search product" ?

Why the bashing on Elasticsearch? We are using it to index log files; we have over 275 million documents in our index and performance has been pretty impressive.

What kind of hardware are you running that on? We are setting up a larger cluster, and are interested in the config of others. Thnx!

We're running on five EC2 instances, each instance is running Elasticsearch configured to use 25GB of RAM. With the current data set we might be able to get by with less RAM, we're still in the process of figuring out what works best for us.

That's why you could look at IndexDen.com which powered by Sphinx Search cluster :)