Module signature

Signature module contains foundational types that are used to represent signatures, types, and return types of functions in DataFusion.

Structs

ImplicitCoercion

Defines rules for implicit type coercion, specifying which source types can be coerced and the default type to use when coercing.

Signature

Defines the supported argument types (TypeSignature) and Volatility for a function.

Enums

ArrayFunctionArgument

ArrayFunctionSignature

Coercion

Represents type coercion rules for function arguments, specifying both the desired type and optional implicit coercion rules for source types.

TypeSignature

A function’s type signature defines the types of arguments the function supports.

TypeSignatureClass

Represents the class of types that can be used in a function signature.

Volatility

A function’s volatility, which defines the functions eligibility for certain optimizations

Constants

FIXED_SIZE_LIST_WILDCARD

Constant that is used as a placeholder for any valid fixed size list. This is used where a function can accept a fixed size list type with any valid length. It exists to avoid the need to enumerate all possible fixed size list lengths.

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.