Elasticsearch Understanding and Manipulating Elasticsearch Index Settings

By Opster Team

Updated: Jul 23, 2023

| 2 min read

Introduction 

Elasticsearch index settings are a crucial aspect of managing and optimizing your Elasticsearch cluster. They allow you to control various parameters of your indices, such as the number of shards, replicas, and the refresh interval. This article will delve into the details of how to retrieve and manipulate these settings. If you want to learn about Elasticsearch index – how to create, list, query and delete indices, check out this guide. 

Retrieving Index Settings

To retrieve the settings of an index, you can use the GET index settings API. This API returns the settings of the specified index. The basic syntax of this API is as follows:

GET /<index>/_settings

Here, `<index>` is the name of the index whose settings you want to retrieve. For example, if you have an index named `my_index`, you can retrieve its settings using the following command:

GET /my_index/_settings

This command will return a JSON object containing the settings of `my_index`.

Changing Index Settings

You can change the settings of an index using the PUT index settings API. This API allows you to modify various settings of an index, such as the number of replicas and the refresh interval. The basic syntax of this API is as follows:

PUT /<index>/_settings
{
  "index" : {
    "<setting>" : "<value>"
  }
}

Here, `<index>` is the name of the index whose settings you want to change, `<setting>` is the name of the setting you want to change, and `<value>` is the new value for the setting. For example, if you want to change the number of replicas of `my_index` to 2, you can use the following command:

PUT /my_index/_settings
{
  "index" : {
    "number_of_replicas" : 2
  }
}

Please note that not all settings can be changed after an index is created. Some settings, such as the number of shards, can only be set at the time of index creation.

Understanding Index Settings

There are numerous index settings that you can manipulate to optimize your Elasticsearch cluster. Here are a few important ones:

1. `number_of_shards`: This setting determines the number of primary shards that an index should have. It can only be set at the time of index creation.

2. `number_of_replicas`: This setting determines the number of replica shards (copies) that each primary shard should have. It can be changed at any time.

3. `refresh_interval`: This setting determines how often Elasticsearch refreshes the data in an index. It can be changed at any time.

4. `index.routing.allocation.include._name`: This setting allows you to control on which nodes of your cluster the shards of an index are allocated. It can be changed at any time.

Conclusion 

In conclusion, understanding and manipulating Elasticsearch index settings is a crucial aspect of managing and optimizing your Elasticsearch cluster. By properly configuring these settings, you can ensure that your indices are distributed and replicated in a way that maximizes the performance and reliability of your cluster.