Databend is an open-source, cloud-native distributed SQL query engine and data warehouse, built in Rust. It provides a full SQL interface for analytical workloads, supporting operations such as SELECT, INSERT, COPY INTO/OUT, MERGE INTO, and complex aggregations with window functions, subqueries, and joins. The architecture follows a storage-compute separation model: a metadata service (Meta) manages schemas, users, and catalogs via a Raft-based consensus layer, while query nodes handle SQL parsing, planning, optimization (Cascades optimizer with rule-based and cost-based passes), and distributed execution over a pipelined framework. Multiple storage engines are supported, including a native columnar Fuse engine optimized for cloud object stores (S3, MinIO, Azure Blob), as well as external formats like Iceberg, Delta Lake, Hive, Paimon, Parquet, and ORC. The system exposes access via MySQL wire protocol, HTTP API, Flight SQL, and gRPC, and includes enterprise features such as data masking, row access policies, materialized views, streams, network policies, and role-based access control.