what is settings in elastic search - elasticsearch

Question

I am very new to elastic search. I need to know what is settings in the index.is it optional? what happens if we don't include it and what happens if we don't include shards in settings.

Answer 1

If you're new to Elasticsearch, it's important that you understand the basic terminologies of Elastic search first.
cluster – An Elasticsearch cluster consists of one or more nodes and is identifiable by its cluster name.
node – A single Elasticsearch instance. In most environments, each node runs on a separate box or virtual machine.
index – In Elasticsearch, an index is a collection of documents like the database in mysql.
shard – Because Elasticsearch is a distributed search engine, an index is usually split into elements known as shards that are distributed across multiple nodes. Elasticsearch automatically manages the arrangement of these shards. It also rebalances the shards as necessary, so users need not worry about the details.
replica – By default, Elasticsearch creates five primary shards and one replica for each index. This means that each index will consist of five primary shards, and each shard will have one copy.
Settings are generally used to define the overall architecture of your application. It differs based on the requirement of the application.
It contains the number of shards, no of Replica sets, etc. This information is helpful to design our Elastic according to the need of the application as below:
{
"settings" : {
"index" : {
"number_of_shards" : 3,
"number_of_replicas" : 2
}
}
}
For further clarification you can visit the official documentation of Elastic community, that is very well written here.
Setting in ElasticSearch