Databend Query is a Distributed Query Engine at scale.

• ast, new version of sql parser based on nom-rule.
• catalog contains structures and traits for catalogs management, Catalog, Database, Table and TableContext.
• codegen is used to generate the arithmetic result type.
• config provides config support for databend query.
• datablocks, Vec collection, which encapsulates some common methods, and will be gradually migrated to expressions.
• datavalues, the definition of each type of Column, which represents the layout of data in memory, will be gradually migrated to expressions.
• expression, the new scalar expression framework with expression definition (AST), type checking, and evaluation runtime.
• formats, the serialization and deserialization of data in various formats to the outside.
• functions, scalar functions and aggregate functions, etc., will be gradually migrated to functions-v2.
• functions-v2, scalar functions and aggregate functions, etc., based on expression.
• management for clusters, quotas, etc.
• pipeline implements the scheduling framework for physical operators.
• planners builds an execution plan from the user's SQL statement and represents the query with different types of relational operators.
• service -> databend-query, the query service library of Databend.
• settings, global and session level settings.
• storages relates to table engines, including the commonly used fuse engine and indexes etc.
• streams contains data sources and streams.
• users, role-based access and control.
• ee contains enterprise functionalities.
• ee-features contains enterprise features.