Crate datafusion_expr

DataFusion is an extensible query execution framework that uses Apache Arrow as its in-memory format.

This crate is a submodule of DataFusion that provides types representing logical query plans (LogicalPlan) and logical expressions (Expr) as well as utilities for working with these types.

The expr_fn module contains functions for creating expressions.

Re-exports

• pub use aggregate_function::AggregateFunction;
• pub use expr::Between;
• pub use expr::BinaryExpr;
• pub use expr::Case;
• pub use expr::Cast;
• pub use expr::Expr;
• pub use expr::GetFieldAccess;
• pub use expr::GetIndexedField;
• pub use expr::GroupingSet;
• pub use expr::Like;
• pub use expr::ScalarFunctionDefinition;
• pub use expr::TryCast;
• pub use expr::WindowFunctionDefinition;
• pub use expr_schema::ExprSchemable;
• pub use function::AccumulatorFactoryFunction;
• pub use function::PartitionEvaluatorFactory;
• pub use function::ReturnTypeFunction;
• pub use function::ScalarFunctionImplementation;
• pub use function::StateTypeFunction;
• pub use groups_accumulator::EmitTo;
• pub use groups_accumulator::GroupsAccumulator;
• pub use window_frame::WindowFrame;
• pub use window_frame::WindowFrameBound;
• pub use window_frame::WindowFrameUnits;
• pub use expr_fn::*;
• pub use logical_plan::*;

Modules

• aggregate_function
  Aggregate function module contains all built-in aggregate functions definitions
• conditional_expressions
  Conditional expressions
• execution_props
• expr
  Logical Expressions: Expr
• expr_fn
  Functions for creating logical expressions
• expr_rewriter
  Expression rewriter
• expr_schema
• field_util
  Utility functions for complex field access
• function
  Function module contains typing and signature for built-in and user defined functions.
• groups_accumulator
  Vectorized GroupsAccumulator
• interval_arithmetic
  Interval arithmetic library
• logical_plan
• simplify
  Structs and traits to provide the information needed for expression simplification.
• tree_node
  Tree node implementation for logical expr and logical plan
• type_coercion
  Type coercion rules for DataFusion
• utils
  Expression utilities
• var_provider
  Variable provider
• window_frame
  Window frame module
• window_state
  Structures used to hold window function state (for implementing WindowUDFs)

Macros

• expr_vec_fmt

Structs

• AggregateUDF
  Logical representation of a user-defined aggregate function (UDAF).
• ScalarUDF
  Logical representation of a Scalar User Defined Function.
• Signature
  Defines the supported argument types (TypeSignature) and Volatility for a function.
• WindowUDF
  Logical representation of a user-defined window function (UDWF) A UDWF is different from a UDF in that it is stateful across batches.

Enums

• BuiltInWindowFunction
  A window function built in to DataFusion
• BuiltinScalarFunction
  Enum of all built-in scalar functions
• ColumnarValue
  Represents the result of evaluating an expression: either a single ScalarValue or an ArrayRef.
• Operator
  Operators applied to expressions
• TableProviderFilterPushDown
  Indicates whether and how a filter expression can be handled by a TableProvider for table scans.
• TableType
  Indicates the type of this table for metadata/catalog purposes.
• TypeSignature
  A function’s type signature defines the types of arguments the function supports.
• Volatility
  A function’s volatility, which defines the functions eligibility for certain optimizations

Constants

• TIMEZONE_WILDCARD
  Constant that is used as a placeholder for any valid timezone. This is used where a function can accept a timestamp type with any valid timezone, it exists to avoid the need to enumerate all possible timezones. See TypeSignature for more details.

Traits

• Accumulator
  Tracks an aggregate function’s state.
• AggregateUDFImpl
  Trait for implementing AggregateUDF.
• Literal
  Trait for converting a type to a Literal literal expression.
• PartitionEvaluator
  Partition evaluator for Window Functions
• ScalarUDFImpl
  Trait for implementing ScalarUDF.
• TableSource
  The TableSource trait is used during logical query planning and optimizations and provides access to schema information and filter push-down capabilities. This trait provides a subset of the functionality of the TableProvider trait in the core datafusion crate. The TableProvider trait provides additional capabilities needed for physical query execution (such as the ability to perform a scan). The reason for having two separate traits is to avoid having the logical plan code be dependent on the DataFusion execution engine. Other projects may want to use DataFusion’s logical plans and have their own execution engine.
• TimestampLiteral
  Trait for converting a type to a literal timestamp
• WindowUDFImpl
  Trait for implementing WindowUDF.

Functions

• lit
  Create a literal expression
• lit_timestamp_nano
  Create a literal timestamp expression

Type Aliases

• FuncMonotonicity
  Monotonicity of the ScalarFunctionExpr with respect to its arguments. Each element of this vector corresponds to an argument and indicates whether the function’s behavior is monotonic, or non-monotonic/unknown for that argument, namely: