If you want to update an index's mappings to add or update field types after index creation, you can do so with the update mapping API operation.
Note that you cannot use this operation to update mappings that already map to existing data in the index. You must first create a new index with your desired mappings, and then use the [reindex API operation]({{site.url}}{{site.baseurl}}/opensearch/reindex-data) to map all the documents from your old index to the new index. If you don't want any downtime while reindexing your indices, you can use [aliases]({{site.url}}{{site.baseurl}}/opensearch/index-alias).
You can also use the update mapping operation to update multiple indices with one request.
```
PUT /<target-index1>,<target-index2>/_mapping
```
## URL parameters
All update mapping parameters are optional.
Parameter | Data Type | Description
:--- | :--- | :---
allow_no_indices | Boolean | If false, the request returns an error if any wildcard expresion or index alias targets any closed or missing indices. Defaults to false.
expand_wildcards | String | Expands wildcard expressions to different indices. Combine multiple values with commas. Available values are `all` (match all indices), `open` (match open indices), `closed` (match closed indices), `hidden` (match hidden indices), and `none` (do not accept wildcard expressions), which must be used with `open`, `closed`, or both. Default is `open`.
ignore_unavailable | Boolean | If true, OpenSearch does not include missing or closed indices in the response.
master_timeout | Time | How long to wait for a connection to the master node. Default is `30s`.
timeout | Time | How long to wait for the response to return. Default is `30s`.
write_index_only | Boolean | If true, the specified mappings are applied only to the write index.
## Request body
The request body must contain `properties`, which has all of the mappings that you want to update.