NRT, flush, refresh, and transaction log

In an ideal search solution, when new data is indexed, it is instantly available for searching. When you start Elasticsearch, this is exactly how it works even in distributed environments. However, this is not the whole truth, and we will show you why it is like this.

Let's start by indexing an example document to the newly created index using the following command:

curl -XPOST localhost:9200/test/test/1 -d '{ "title": "test" }'

Now, let's replace this document, and let's try to find it immediately. In order to do this, we'll use the following command chain:

curl -XPOST localhost:9200/test/test/1 -d '{ "title": "test2" }' ; curl -XGET 'localhost:9200/test/test/_search?pretty'

The preceding command will probably result in a response that is very similar to the following one:

{"_index":"test","_type":"test","_id":"1","_version":2,"created":false}{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 5,
    "successful" : 5,
    "failed" :...