> 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

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