Index refresh interval in Elasticsearch

Introduction

The index refresh interval controls how often Elasticsearch makes new data searchable. It helps balance speed and performance.

When you want new data to appear quickly in search results.

When you want to reduce system load by refreshing less often.

When you are indexing large amounts of data and want to optimize speed.

When you want to control how fresh your search results are.

When tuning Elasticsearch for different workloads like logging or analytics.

Syntax

Elasticsearch

PUT /my_index/_settings
{
  "index": {
    "refresh_interval": "30s"
  }
}

The refresh_interval value can be set in seconds (e.g., "30s") or milliseconds (e.g., "500ms").

Setting refresh_interval to -1 disables automatic refreshes.

Examples

Sets the refresh interval to 1 second, so new data becomes searchable every second.

Elasticsearch

PUT /my_index/_settings
{
  "index": {
    "refresh_interval": "1s"
  }
}

Disables automatic refresh. Use this during heavy indexing to improve speed.

Elasticsearch

PUT /my_index/_settings
{
  "index": {
    "refresh_interval": -1
  }
}

Sets refresh interval to 5 seconds, balancing freshness and performance.

Elasticsearch

PUT /my_index/_settings
{
  "index": {
    "refresh_interval": "5s"
  }
}

Sample Program

Creates an index named 'test_index' with a refresh interval of 10 seconds, then retrieves the settings to confirm.

Elasticsearch

PUT /test_index
{
  "settings": {
    "index": {
      "refresh_interval": "10s"
    }
  }
}

GET /test_index/_settings

Important Notes

A shorter refresh interval means data appears in search results faster but uses more resources.

A longer refresh interval improves indexing speed but delays data visibility in searches.

You can change the refresh interval anytime without reindexing your data.

Summary

The index refresh interval controls how often new data is searchable.

Set it shorter for fresh data or longer for better indexing performance.

You can disable automatic refresh during heavy indexing to speed up the process.