Metadata search for RAG Engine Use schema-based metadata search in Vertex AI RAG Engine

## Feature Feature **Metadata search for RAG Engine** Use schema-based metadata search in Vertex AI RAG Engine. You can define a metadata schema for a corpus, attach metadata to files within that corpus, and use this metadata to filter contexts during retrieval. For more information, see[Filter with metadata search](https://cloud.google.com/vertex-ai/generative-ai/docs/rag-engine/use-metadata-search).