Class DuckDbVectorMethods

Extension methods on DuckDbVectorReader<T> and DuckDbVectorRawReader<T>.

Inheritance

object

DuckDbVectorMethods

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: Mallard

Assembly: Mallard.dll

Syntax

public static class DuckDbVectorMethods

Remarks

These methods are extension methods rather than instance methods primarily so they can be precisely defined to apply to certain cases for the type parameter.

Methods

AsSpan<T>(in DuckDbVectorRawReader<T>)

Get the contents of a DuckDB vector as a .NET span.

Declaration

public static ReadOnlySpan<T> AsSpan<T>(this in DuckDbVectorRawReader<T> vector) where T : unmanaged

Parameters

Type	Name	Description
DuckDbVectorRawReader<T>	vector	The DuckDB vector to read from.

Returns

Type	Description
ReadOnlySpan<T>	Span covering all the elements of the DuckDB vector. Note that elements of the vector that are invalid, may be "garbage" or un-initialized when indexed using the returned span.

Type Parameters

Name	Description
T	The type of element in the DuckDB vector. This method is only available for "primitive" types, i.e. types containing data of fixed size, as variable-length data cannot be safely exposed except through a "ref struct", but a "ref struct" cannot be the element type of ReadOnlySpan<T>.

Exceptions

Type	Condition
InvalidOperationException	When T is DuckDbArrayRef. A DuckDB vector of such type does not have directly have elements, and therefore no span can be made available. The contents of vector are made available in the "children vector".

GetChildrenRawVector<T>(in DuckDbVectorRawReader<DuckDbArrayRef>)

Get the raw vector for the children of a vector of lists.

Declaration

public static DuckDbVectorRawReader<T> GetChildrenRawVector<T>(this in DuckDbVectorRawReader<DuckDbArrayRef> parent) where T : unmanaged, allows ref struct

Parameters

Type	Name	Description
DuckDbVectorRawReader<DuckDbArrayRef>	parent	The raw vector of lists.

Returns

Type	Description
DuckDbVectorRawReader<T>	The raw vector for reading the children (items) of the lists inside parent.

Type Parameters

Name	Description
T	The element type of the lists. It must be compatible with DuckDbVectorRawReader<T>.

GetChildrenRaw<T>(in DuckDbVectorRawReader<DuckDbListRef>)

Retrieve the vector containing all the children across all lists in a vector of lists, allowing "raw" access (spans).

Declaration

public static DuckDbVectorRawReader<T> GetChildrenRaw<T>(this in DuckDbVectorRawReader<DuckDbListRef> parent) where T : unmanaged, allows ref struct

Parameters

Type	Name	Description
DuckDbVectorRawReader<DuckDbListRef>	parent	The vector of lists.

Returns

Type	Description
DuckDbVectorRawReader<T>	The lists' children, collected into one vector, i.e. the "children vector" or "vector of list children".

Type Parameters

Name	Description
T	The .NET type to bind an element of the lists to.

Exceptions

Type	Condition
DuckDbException

GetMemberItemsRaw<T>(in DuckDbVectorRawReader<DuckDbStructRef>, int)

Retrieve the vector containing all the items of one member of a struct, within a struct-typed parent vector.

Declaration

public static DuckDbVectorRawReader<T> GetMemberItemsRaw<T>(this in DuckDbVectorRawReader<DuckDbStructRef> parent, int memberIndex) where T : unmanaged, allows ref struct

Parameters

Type	Name	Description
DuckDbVectorRawReader<DuckDbStructRef>	parent	The struct-typed parent vector.
int	memberIndex	The index of the member in the struct, numbered starting from 0.

Returns

Type	Description
DuckDbVectorRawReader<T>	The lists' children, collected into one vector, i.e. the "children vector" or "vector of list children".

Type Parameters

Name	Description
T	The .NET type to bind struct member values to.

GetMemberName(in DuckDbVectorRawReader<DuckDbStructRef>, int)

Get the name of a member for a struct-typed vector.

Declaration

public static string GetMemberName(this in DuckDbVectorRawReader<DuckDbStructRef> parent, int memberIndex)

Parameters

Type	Name	Description
DuckDbVectorRawReader<DuckDbStructRef>	parent	The struct-typed DuckDB vector.
int	memberIndex	The index of the member in the struct, numbered from 0 (inclusive) to ElementSize (exclusive).

Returns

Type	Description
string	The name of the struct member.

Remarks

The name needs to be queried from DuckDB every time this method is called, so the caller should cache the result if it is needed multiple times.

GetNullableValue<T>(in DuckDbVectorReader<T>, int)

Retrieve one element from a DuckDB vector, allowing null values.

Declaration

public static T? GetNullableValue<T>(this in DuckDbVectorReader<T> vector, int index) where T : struct

Parameters

Type	Name	Description
DuckDbVectorReader<T>	vector	The vector to retrieve from.
int	index	The index of the desired element.

Returns

Type	Description
T?	The value of the selected element, or null (if it is null in the DuckDB vector).

Type Parameters

Name	Description
T	The .NET value type for the element.

Exceptions

Type	Condition
IndexOutOfRangeException	The index is out of range for the vector.

GetNullable<T>(in DuckDbVectorReader<T>, int)

Retrieve one element from a DuckDB vector, allowing null references.

Declaration

public static T? GetNullable<T>(this in DuckDbVectorReader<T> vector, int index) where T : class

Parameters

Type	Name	Description
DuckDbVectorReader<T>	vector	The vector to retrieve from.
int	index	The index of the desired element.

Returns

Type	Description
T	The value of the selected element, or null (if it is null in the DuckDB vector).

Type Parameters

Name	Description
T	The .NET reference type for the element.

Exceptions

Type	Condition
IndexOutOfRangeException	The index is out of range for the vector.