# Batch Materialization Engine A batch materialization engine is a component of Feast that's responsible for moving data from the offline store into the online store. A materialization engine abstracts over specific technologies or frameworks that are used to materialize data. It allows users to use a pure local serialized approach (which is the default LocalMaterializationEngine), or delegates the materialization to seperate components (e.g. AWS Lambda, as implemented by the the LambdaMaterializaionEngine). If the built-in engines are not sufficient, you can create your own custom materialization engine. Please see [this guide](https://docs.feast.dev/v0.38-branch/how-to-guides/customizing-feast/creating-a-custom-materialization-engine) for more details. Please see [feature\_store.yaml](https://docs.feast.dev/v0.38-branch/reference/feature-repository/feature-store-yaml#overview) for configuring engines. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.feast.dev/v0.38-branch/getting-started/architecture-and-components/batch-materialization-engine.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.