# AOSOPS01-BP03 Remove unused indexes
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 Regularly review and remove unused indexes to optimize your OpenSearch Service domain's performance and reduce costs. Unused indexes, even when inactive, continue to consume domain resources including memory, CPU, and storage. 

 **Level of risk exposed if this best practice is not established:** Medium 

 **Desired outcome:** Unused indexes are removed to optimize performance and reduce costs. 

 **Benefits of establishing this best practice:** 
+  **Improve query performance:** Removing unused indexes can help reduce the computational resources needed to manage your OpenSearch infrastructure, leading to improved query performance and faster search results. 
+  **Lower costs:** By reducing the number of indices that need to be managed, you can also lower costs associated with storing and processing data in Amazon OpenSearch Service. 
+  **Enhance domain efficiency:** Regularly reviewing and pruning unused indexes helps improve your OpenSearch Service domain efficiency, scalability, and cost-effectiveness, making it easier to manage and maintain your OpenSearch infrastructure. 

## Implementation guidance
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 To optimize the performance and cost-effectiveness of your OpenSearch Service domains, remove any unused indexes that are no longer required. This can help reduce the computational resources needed to manage your OpenSearch Service infrastructure, leading to improved query performance and lower costs. By regularly reviewing and pruning unused indexes, you improve your OpenSearch Service domain efficiency, scalability, and cost-effectiveness. 

### Implementation steps
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+  **Identify unused indexes:** Unused indexes are typically those that haven't been updated or queried for a specified period. To identify them, you can use OpenSearch Dashboards or the OpenSearch API. 
+  **Option 1:** Use OpenSearch Dashboards by going to Index Management, then Indexes, then Indexes. 
+  **Option 2:** Use the OpenSearch API: 
  +  Use the `_cat/indices` API to list all indexes along with their name, status and size. 

```
GET _cat/indices?v
```
+  Once you identify unneeded indices, delete them using the Dashboard or with the API command: 

```
DELETE /<index_name
```
+  You can also create an ISM policy to delete indexes after they reach a certain age. For details on how to create an ISM policy, see [AOSOPS01-BP01](aosops01-bp01.md). 

## Resources
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+  [Delete index](https://opensearch.org/docs/latest/api-reference/index-apis/delete-index/)