How to Update Elasticsearch Index Settings

Sometimes you need to change index settings, like refresh interval or number of shards. For that, you need to change the index settings.

Important things to note:

• Always test changes in a non-production environment first.
• Be cautious when updating settings on large indices, as it may impact performance.
• Some settings can only be changed at index creation time and cannot be updated later.
• Use index templates to set default settings for new indices.
• Monitor cluster health and performance after making changes to ensure stability.

Steps to change index settings

1. For dynamic settings: a. Use the Update Index Settings API:

   PUT /your_index_name/_settings
   {
     "index": {
       "setting_name": "new_value"
     }
   }
   

2. For static settings: a. Close the index:

   POST /your_index_name/_close
   

   b. Update the settings:

   PUT /your_index_name/_settings
   {
     "index": {
       "setting_name": "new_value"
     }
   }
   

   c. Open the index:

   POST /your_index_name/_open
   

3. Verify the changes using the Get Index Settings API:

   GET /your_index_name/_settings
   

Frequently Asked Questions

Q: What's the difference between dynamic and static index settings?
A: Dynamic settings can be changed on a live index without closing it, while static settings require the index to be closed before updating.

Q: Can I update multiple settings at once?
A: Yes, you can update multiple settings in a single API call by including them in the same JSON body.

Q: How do I know which settings are dynamic and which are static?
A: Consult the Elasticsearch documentation for each setting. Dynamic settings are usually marked as such in the documentation.

Q: What happens if I try to update a static setting without closing the index?
A: Elasticsearch will return an error, and the setting will not be updated.

Q: Are there any risks associated with updating index settings?
A: Yes, some settings can significantly impact performance or behavior. Always test changes in a safe environment and understand the implications before applying them to production indices.