Struct DuckDbColumnInfo

Describes the data type of (the items in) a column resulting from a DuckDB query.

Implements

IEquatable<DuckDbColumnInfo>

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

ValueType.ToString()

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Namespace: Mallard

Assembly: Mallard.dll

Syntax

public readonly record struct DuckDbColumnInfo : IEquatable<DuckDbColumnInfo>

Remarks

The properties in this type provide information to decode data coming in from a DuckDB column. This information is sufficient for "simple" types (such as integers, decimals).

For "complex" types (of some composited/nested nature), specialized API calls to the DuckDB native library may be necessary to decode/describe them fully. Those API calls are made available elsewhere in this library as they require more complex state/resource management. This type optimizes for the by far the most common case, where basic information on the DuckDB type/column can be gathered cheaply upfront, and stored in an inert structure that can be passed around and accessed (in .NET code) with no restrictions.

This .NET type is also used to describe a DuckDB column that is nested within another, e.g. a member of a structure (STRUCT in DuckDB SQL).

The name of the column (if any) is not part of this information set, because it is irrelevant for decoding the data from the column. By omitting the name, this .NET type can also implement structural equality on the type information.

Properties

DecimalScale

The number of digits after the decimal point, when the logical type is Decimal.

Declaration

public byte DecimalScale { get; }

Property Value

Type	Description
byte	The number of digits, or zero if inapplicable.

ElementSize

The "size" applicable to certain types of items that can be stored in a DuckDB vector.

Declaration

public int ElementSize { get; }

Property Value

Type	Description
int

Remarks

Item type	What this property holds
Fixed-sized array (ARRAY in DuckDB SQL)	The size of those arrays
Enumeration (ENUM in DuckDB SQL)	The size (number of entries) in the enumeration type
Fixed-point decimal number (DECIMAL in DuckDB SQL)	The maximum number of decimal digits ("width")
Structures (STRUCT in DuckDB SQL)	The number of members in the structural type

StorageKind

The actual representation kind used for storage within vectors, when the logical type is Enum or Decimal.

Declaration

public DuckDbValueKind StorageKind { get; }

Property Value

Type	Description
DuckDbValueKind	The storage kind of element in the vector, or Invalid if inapplicable.

ValueKind

The kind of item data, used to verify correctly-typed access to items of the vector.

Declaration

public DuckDbValueKind ValueKind { get; }

Property Value

Type	Description
DuckDbValueKind

Implements

IEquatable<T>