Struct Overload

pkg/sql/sem/tree/overload.go:174–307

Overload is one of the overloads of a built-in function. Each FunctionDefinition may contain one or more overloads.

// Overload is one of the overloads of a built-in function.
// Each FunctionDefinition may contain one or more overloads.
type Overload struct {
	Types      TypeList
	ReturnType ReturnTyper
	Volatility volatility.V
	OverloadPreference

	// Info is a description of the function, which is surfaced on the CockroachDB
	// docs site on the "Functions and Operators" page. Descriptions typically use
	// third-person with the function as an implicit subject (e.g. "Calculates
	// infinity"), but should focus more on ease of understanding so other structures
	// might be more appropriate.
	Info string

	AggregateFunc AggregateOverload
	WindowFunc    WindowOverload

	// Only one of the "Fn", "FnWithExprs", "Generate", "GeneratorWithExprs",
	// "SQLFn" and "Body" attributes can be set.

	// Class is the kind of built-in function (normal/aggregate/window/etc.)
	Class FunctionClass

	// Fn is the normal builtin implementation function. It's for functions that
	// take in Datums and return a Datum.
	//
	// The opaque wrapper needs to be type asserted into eval.FnOverload.
	Fn FnOverload

	// FnWithExprs is for builtins that need access to their arguments as Exprs
	// and not pre-evaluated Datums, but is otherwise identical to Fn.
	FnWithExprs FnWithExprsOverload

	// Generator is for SRFs. SRFs take Datums and return multiple rows of Datums.
	Generator GeneratorOverload

	// GeneratorWithExprs is for SRFs that need access to their arguments as Exprs
	// and not pre-evaluated Datums, but is otherwise identical to Generator.
	GeneratorWithExprs GeneratorWithExprsOverload

	// SQLFn must be set for overloads of type SQLClass. It should return a SQL
	// statement which will be executed as a common table expression in the query.
	SQLFn SQLFnOverload

	// OnTypeCheck, if set, is called every time this overload is type checked.
	OnTypeCheck func()

	// SpecializedVecBuiltin is used to let the vectorized engine
	// know when an Overload has a specialized vectorized operator.
	SpecializedVecBuiltin SpecializedVectorizedBuiltin

	// IgnoreVolatilityCheck ignores checking the functions overload's
	// Volatility against Postgres's Volatility at test time.
	// This should be used with caution.
	IgnoreVolatilityCheck bool

	// Oid is the cached oidHasher.BuiltinOid result for this Overload. It's
	// populated at init-time.
	Oid oid.Oid