> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/connectors/other/langchain-mariadb/api-reference.md).

# API Reference

- [Vector Stores](https://mariadb.com/docs/connectors/other/langchain-mariadb/api-reference/vectorstores.md): MariaDBStore provides a LangChain-compatible vector store backed by MariaDB, supporting similarity search, metadata filtering, and maximal marginal relevance retrieval.
- [Chat Message History](https://mariadb.com/docs/connectors/other/langchain-mariadb/api-reference/chat_message_histories.md): MariaDBChatMessageHistory persists LangChain conversation history to a MariaDB database table, providing methods to add, retrieve, and clear messages per session.
- [Expression Filters](https://mariadb.com/docs/connectors/other/langchain-mariadb/api-reference/expression_filter.md): Expression filter reference for langchain-mariadb, documenting the operator enum, filter builder classes, and MariaDBFilterExpressionConverter for metadata-based vector queries.
- [Translator](https://mariadb.com/docs/connectors/other/langchain-mariadb/api-reference/translator.md): MariaDBTranslator converts LangChain internal query language operations and comparisons into valid MariaDB filter dictionaries for use with structured vector store queries.