How much RealTime is Elasticsearch, Solr and DSE realtime search?

Question

From some last couple of weeks, I have been working around Elasticsearch and Solr, and trying to do OLTP processing in real time. However, what comes to me is they claims(especially ES) to be real time. The meaning of real time looks a lot fuzzy to me.

If we go deep into it, both ES and Solr, defines a refresh rate or a soft-commit rate, after which the newly indexed documents would be available for search, effectively providing only Near-Real time capabilities.

It looks like by Real time search, it is either a marketing statement to call it real time, or they make the word fuzzy by talking about Real Time Search rather than batch or analytical processing.

Am I correct, or correct me if I am wrong, and there is a real-time search possible in a typical OLTP system, where every transaction has search visibility to last document ?

Answer 1

Elasticsearch is a Near Real Time search engine for search. Elasticsearch is Real Time for operations like Create, Update, Delete and Get.

By default, refresh is 1 second. In some use cases, it could appear as real time. For example, I was working for a french gov service and we were producing statistics per day. So for our use case, it was somehow real time from our perspective.

For logs for example, 1 second is enough in most use cases.

You can modify this default value but it comes with a cost.

If you really need real time, then you probably want to use a SQL database.

My 2 cents.