Trait ByteSize 

pub trait ByteSize {
    // Required methods
    fn est_bytes(&self) -> usize;
    fn logical_bytes(&self) -> usize;
}

Trait for estimating the memory footprint of a type.

Returns the estimated number of bytes occupied by the object in memory, including all owned data buffers, masks, and nested structures.

For types with directly calculatable sizes (e.g., n * size_of::<T>()), this returns the exact value. For complex types, this provides a best estimate.

Required Methods

fn est_bytes(&self) -> usize

Returns the estimated byte size of this object in memory.

This includes:

• Data buffers (values, offsets, indices)
• Null masks (bitmaps)
• Dictionary data (for categorical types)
• Nested structures (for recursive types)

Does not include:

• Stack size of the struct itself (only heap allocations)
• Arc pointer overhead (counted once per allocation, not per reference)

fn logical_bytes(&self) -> usize

Returns the exact logical byte size of the data.

The figure counts the bytes the values occupy in Arrow buffer terms. Value buffers count len * element_width, offsets count (len + 1) * offset_width, null masks count ceil(len / 8) and dictionaries count their summed string contents. Capacity slack left behind by buffer growth is excluded, which is the difference from est_bytes. That method reports the memory footprint of the allocations, where this one reports the data itself, so callers use it for throughput denominators and wire-size planning where the figure must match the payload.

Views report the window they cover rather than the backing array.

Warning

The non-Arrow numerical container types (Matrix, NdArray and their chunked and view forms, plus XArray) do not yet define logical byte accounting currently and panic with unimplemented! when called.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl ByteSize for Array

ByteSize for Array enum

impl ByteSize for ArrayV

Available on crate feature views only.

ByteSize for ArrayV - proportional estimate from underlying array

impl ByteSize for Bitmask

ByteSize for Bitmask - bit-packed bitmask

impl ByteSize for Cube

Available on crate feature cube only.

impl ByteSize for Field

ByteSize for Field - metadata only, minimal size

impl ByteSize for FieldArray

ByteSize for FieldArray - field metadata + array data

impl ByteSize for Matrix

Available on crate feature matrix only.

impl ByteSize for NumericArray

ByteSize for NumericArray enum

impl ByteSize for Scalar

Available on crate features scalar_type and value_type only.

ByteSize for Scalar (when scalar_type feature is enabled)

impl ByteSize for SuperArray

Available on crate feature chunked only.

impl ByteSize for SuperArrayV

Available on crate features chunked and views only.

ByteSize for SuperArrayV - sum of slice estimates

impl ByteSize for SuperTable

Available on crate feature chunked only.

impl ByteSize for SuperTableV

Available on crate features chunked and views only.

ByteSize for SuperTableV - sum of slice estimates

impl ByteSize for Table

ByteSize for Table - sum of all column arrays

impl ByteSize for TableV

Available on crate feature views only.

ByteSize for TableV - sum of column view estimates

impl ByteSize for TemporalArray

Available on crate feature datetime only.

ByteSize for TemporalArray enum (when datetime feature is enabled)

impl ByteSize for TextArray

ByteSize for TextArray enum

impl ByteSize for Value

Available on crate feature value_type only.

ByteSize for Value enum - delegates to inner types

impl<T: Float> ByteSize for NdArrayV<T>

Available on crate features ndarray and views only.

impl<T: Float> ByteSize for SuperNdArrayV<T>

Available on crate features chunked and ndarray and views only.

impl<T: Float> ByteSize for XArray<T>

Available on crate feature xarray only.

impl<T: Integer> ByteSize for CategoricalArray<T>

ByteSize for CategoricalArray

impl<T> ByteSize for BooleanArray<T>

ByteSize for BooleanArray

impl<T> ByteSize for Buffer<T>

ByteSize for Buffer - unified owned/shared buffer

impl<T> ByteSize for DatetimeArray<T>

Available on crate feature datetime only.

impl<T> ByteSize for FloatArray<T>

ByteSize for FloatArray

impl<T> ByteSize for IntegerArray<T>

ByteSize for IntegerArray

impl<T> ByteSize for NdArray<T>

Available on crate feature ndarray only.

impl<T> ByteSize for StringArray<T>

ByteSize for StringArray

impl<T> ByteSize for SuperNdArray<T>

Available on crate features chunked and ndarray only.

impl<T> ByteSize for Vec64<T>

ByteSize for Vec64 - 64-byte aligned vector