How to implement language filtering in Google Vertex AI Search results?

[JollyMusic3]

I’m working with Google Vertex AI Search and trying to figure out how to filter search results by language. In the old Custom Search Engine, there was an ‘lr’ parameter that handled language filtering, but I can’t find similar functionality in the current documentation.

I have a few questions about this:

• Does Vertex AI Search automatically detect and index content language?
• What field name should I use to filter by language in my search queries?
• Do I need to explicitly define language fields in my data schema configuration?

The advanced indexing documentation doesn’t seem to cover language filtering clearly. Any guidance on implementing this would be really helpful.

[mikechen]

Vertex AI Search detects language automatically during indexing, but you can’t filter by it like you could with the old Custom Search. The system knows the language internally, but it’s not exposed for filtering by default. I had to work around this by adding a manual language field to my data schema during ingestion. I called it ‘content_language’ with values like ‘en’, ‘es’, ‘fr’. Then I could filter on that field in my search API calls. The automatic detection is there, but it’s mainly for search relevance - not filtering. You’re better off explicitly defining a language field in your schema config instead of trying to use whatever hidden detection might exist.

[Isaac_Cosmos]

Vertex AI Search detects languages automatically when indexing, but you’ve got to set it up right. It creates a _language field you can use in structured queries. I’ve worked with multilingual indexing before - the auto-detection works pretty well for major languages, but struggles with short snippets or documents that mix languages. You don’t need to define language fields in your schema unless you want to override the automatic detection with your own metadata. To filter results, use the filter parameter in your search API calls like _language = “en” for English. Language codes use standard ISO 639-1 format. Just remember - filtering happens at query time, so you’ll need to rebuild your index if you’re migrating from the old Custom Search setup.