Struct NullBufferBuilder

pub struct NullBufferBuilder { /* private fields */ }

Builder for creating NullBuffer

Performance

This builder only materializes the buffer when we append false. If you only append trues to the builder, what you get will be None when calling finish.

This optimization is very important for the performance as it avoids allocating memory for the null buffer when there are no nulls.

See Self::allocated_size to get the current memory allocated by the builder.

Example

let mut builder = NullBufferBuilder::new(8);
builder.append_n_non_nulls(8);
// If no non null values are appended, the null buffer is not created
let buffer = builder.finish();
assert!(buffer.is_none());
// however, if a null value is appended, the null buffer is created
let mut builder = NullBufferBuilder::new(8);
builder.append_n_non_nulls(7);
builder.append_null();
let buffer = builder.finish().unwrap();
assert_eq!(buffer.len(), 8);
assert_eq!(buffer.iter().collect::<Vec<_>>(), vec![true, true, true, true, true, true, true, false]);

Implementations

impl NullBufferBuilder

pub fn new(capacity: usize) -> NullBufferBuilder

Creates a new empty builder.

Note that this method does not allocate any memory, regardless of the capacity parameter. If an allocation is required, capacity is the size in bits (not bytes) that will be allocated at minimum.

pub fn new_with_len(len: usize) -> NullBufferBuilder

Creates a new builder with given length.

pub fn new_from_buffer(buffer: MutableBuffer, len: usize) -> NullBufferBuilder

Creates a new builder from a MutableBuffer.

pub fn append_n_non_nulls(&mut self, n: usize)

Appends n trues into the builder to indicate that these n items are not nulls.

pub fn append_non_null(&mut self)

Appends a true into the builder to indicate that this item is not null.

pub fn append_n_nulls(&mut self, n: usize)

Appends n falses into the builder to indicate that these n items are nulls.

pub fn append_null(&mut self)

Appends a false into the builder to indicate that this item is null.

pub fn append(&mut self, not_null: bool)

Appends a boolean value into the builder.

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

Gets a bit in the buffer at index

pub fn truncate(&mut self, len: usize)

Truncates the builder to the given length

If len is greater than the buffer’s current length, this has no effect

pub fn append_slice(&mut self, slice: &[bool])

Appends a boolean slice into the builder to indicate the validations of these items.

pub fn append_buffer(&mut self, buffer: &NullBuffer)

Append NullBuffer to this NullBufferBuilder

This is useful when you want to concatenate two null buffers.

pub fn finish(&mut self) -> Option<NullBuffer>

Builds the null buffer and resets the builder. Returns None if the builder only contains trues.

pub fn finish_cloned(&self) -> Option<NullBuffer>

Builds the NullBuffer without resetting the builder.

pub fn as_slice(&self) -> Option<&[u8]>

Returns the inner bitmap builder as slice

pub fn as_slice_mut(&mut self) -> Option<&mut [u8]>

Return a mutable reference to the inner bitmap slice.

pub fn allocated_size(&self) -> usize

Return the allocated size of this builder, in bytes, useful for memory accounting.

impl NullBufferBuilder

pub fn len(&self) -> usize

Return the number of bits in the buffer.

pub fn is_empty(&self) -> bool

Check if the builder is empty.

Trait Implementations

impl Debug for NullBufferBuilder

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

Formats the value using the given formatter.