The language routing feature limits search queries to documents in a specified language.

Language routing  makes querying more precise by reducing the number of false positive matches, since documents are only analyzed for one language. Since language routing optimizes indexing performance and increases query precision, it is recommended to use it when indexing documents. Language routing requires no change to search queries.

Previously, all documents were analyzed for all supported languages. This practice sometimes caused noise when one language's stemming rules collided with another's.

## Add language routing on any type of object

You can add language routing to any type of object via the `LanguageRoutingAttribute` or the conventions API.

### LanguageRoutingAttribute

You can add language routing via the `LanguageRoutingAttribute` on the property. Set it to the desired language when initializing the object.

### Conventions

Another option is to use the conventions API in Search & Navigation.

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Note

After upgrading to Optimizely Search & Navigation 13, reindex the whole site as soon as possible.