How it works

Knowledge bases for Amazon Bedrock help you take advantage of Retrieval Augmented Generation (RAG), a popular technique that involves drawing information from a data store to augment the responses generated by Large Language Models (LLMs). When you set up a knowledge base with your data sources, your application can query the knowledge base to return information to answer the query either with direct quotations from sources or with natural responses generated from the query results.

With knowledge bases, you can build applications that are enriched by the context that is received from querying a knowledge base. It enables a faster time to market by abstracting from the heavy lifting of building pipelines and providing you an out-of-the-box RAG solution to reduce the build time for your application. Adding a knowledge base also increases cost-effectiveness by removing the need to continually train your model to be able to leverage your private data.

The following diagrams illustrate schematically how RAG is carried out. Knowledge base simplifies the setup and implementation of RAG by automating several steps in this process.

Pre-processing data

To enable effective retrieval from private data, a common practice is to first split the documents into manageable chunks for efficient retrieval. The chunks are then converted to embeddings and written to a vector index, while maintaining a mapping to the original document. These embeddings are used to determine semantic similarity between queries and text from the data sources. The following image illustrates pre-processing of data for the vector database.

Runtime execution

At runtime, an embedding model is used to convert the user's query to a vector. The vector index is then queried to find chunks that are semantically similar to the user's query by comparing document vectors to the user query vector. In the final step, the user prompt is augmented with the additional context from the chunks that are retrieved from the vector index. The prompt alongside the additional context is then sent to the model to generate a response for the user. The following image illustrates how RAG operates at runtime to augment responses to user queries.