Struct VariantArray

pub struct VariantArray {
    inner: StructArray,
    metadata_ref: ArrayRef,
    value_ref: ArrayRef,
}

An array of Parquet [Variant] values

A VariantArray wraps an Arrow [StructArray] that stores the underlying metadata and value fields, and adds convenience methods to access the Variants

See VariantArrayBuilder for constructing a VariantArray.

Specification

1. This code follows the conventions for storing variants in Arrow StructArray defined by Extension Type for Parquet Variant arrow and this document. At the time of this writing, this is not yet a standardized Arrow extension type.

Fields

inner: StructArray

StructArray of up to three fields:

1. A required field named metadata which is binary, large_binary, or binary_view

2. An optional field named value that is binary, large_binary, or binary_view

3. An optional field named typed_value which can be any primitive type or be a list, large_list, list_view or struct

NOTE: It is also permissible for the metadata field to be Dictionary-Encoded, preferably (but not required) with an index type of int8.

metadata_ref: ArrayRef

Reference to the metadata column of inner

value_ref: ArrayRef

Reference to the value column of inner

Implementations

impl VariantArray

pub fn try_new(inner: ArrayRef) -> Result<Self, ArrowError>

Creates a new VariantArray from a [StructArray].

Arguments

• inner - The underlying [StructArray] that contains the variant data.

Returns

• A new instance of VariantArray.

Errors:

• If the StructArray does not contain the required fields

Current support

This structure does not (yet) support the full Arrow Variant Array specification.

Only StructArrays with metadata and value fields that are BinaryViewArray are supported. Shredded values are not currently supported nor are using types other than BinaryViewArray

pub fn inner(&self) -> &StructArray

Returns a reference to the underlying [StructArray].

pub fn into_inner(self) -> StructArray

Returns the inner [StructArray], consuming self

pub fn value(&self, index: usize) -> Variant<'_, '_>

Return the [Variant] instance stored at the given row

Panics if the index is out of bounds.

Note: Does not do deep validation of the [Variant], so it is up to the caller to ensure that the metadata and value were constructed correctly.

fn find_metadata_field(array: &StructArray) -> Option<ArrayRef>

fn find_value_field(array: &StructArray) -> Option<ArrayRef>

pub fn metadata_field(&self) -> &ArrayRef

Return a reference to the metadata field of the [StructArray]

pub fn value_field(&self) -> &ArrayRef

Return a reference to the value field of the StructArray

Trait Implementations

impl Array for VariantArray

fn as_any(&self) -> &dyn Any

Returns the array as Any so that it can be downcasted to a specific implementation.

fn to_data(&self) -> ArrayData

Returns the underlying data of this array

fn into_data(self) -> ArrayData

Returns the underlying data of this array

fn data_type(&self) -> &DataType

Returns a reference to the [DataType] of this array.

fn slice(&self, offset: usize, length: usize) -> ArrayRef

Returns a zero-copy slice of this array with the indicated offset and length.

fn len(&self) -> usize

Returns the length (i.e., number of elements) of this array.

fn is_empty(&self) -> bool

Returns whether this array is empty.

fn offset(&self) -> usize

Returns the offset into the underlying data used by this array(-slice). Note that the underlying data can be shared by many arrays. This defaults to 0.

fn nulls(&self) -> Option<&NullBuffer>

Returns the null buffer of this array if any.

fn get_buffer_memory_size(&self) -> usize

Returns the total number of bytes of memory pointed to by this array. The buffers store bytes in the Arrow memory format, and include the data as well as the validity map. Note that this does not always correspond to the exact memory usage of an array, since multiple arrays can share the same buffers or slices thereof.

fn get_array_memory_size(&self) -> usize

Returns the total number of bytes of memory occupied physically by this array. This value will always be greater than returned by get_buffer_memory_size() and includes the overhead of the data structures that contain the pointers to the various buffers.

fn shrink_to_fit(&mut self)

Shrinks the capacity of any exclusively owned buffer as much as possible

fn logical_nulls(&self) -> Option<NullBuffer>

Returns a potentially computed [NullBuffer] that represents the logical null values of this array, if any.

fn is_null(&self, index: usize) -> bool

Returns whether the element at index is null according to [Array::nulls]

fn is_valid(&self, index: usize) -> bool

Returns whether the element at index is not null, the opposite of [Self::is_null].

fn null_count(&self) -> usize

Returns the total number of physical null values in this array.

fn logical_null_count(&self) -> usize

Returns the total number of logical null values in this array.

fn is_nullable(&self) -> bool

Returns false if the array is guaranteed to not contain any logical nulls

impl Debug for VariantArray

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.