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  Recently, I was required to modify my existing elasticsearch index’s field mapping. But the problem is, there is no way to make a change in your existing field-mapping without creating a new index. But if I delete the existing index, all my data will be gone! So, what to do now??? Here comes a great solution! Recently elasticsearch has introduced a new API, RE_INDEX. Let’s see how can we use this to achieve our goal! Before that, I am gonna quote from the elasticsearch API: Reindex does not attempt to set up the destination index. It does not copy the settings of the source index. You should set up the destination index prior to running a _reindex action, including setting up mappings, shard counts, replicas, etc. So, let’s create a backup index : PUT project_copy { "settings" : { "index" : { "number_of_shards" : 5, "number_of_replicas" : 2 } } } Response: { "acknowledged" : true, ...

Those who use elasticsearch for their data storage or data search purposes, sometimes need pagination. Like when we search in google, we see the first page on first result, then below the search result, we can see other search results in different pages which are mentioned below with page number in google's search result page. We can navigate to and from clicking on the pageNumber we are shown. For elasticsearch who has ever implemented pagination in traditional way providing from and size parameters, knows that elasticsearch does not allow more than 10k records for a query.  Those who are interested to have a short brief about different type of ES pagination, can check this  Elasticsearch, how we paginated over 10 000 items .  I am not going to describe full of it rather  a short brief here as the topic suggests. Elastic search provides a mechanism of pagination for more than 10k records and one of them is by search_after method which is much better for some...