Struct NullBufferBuilder 

pub struct NullBufferBuilder { /* private fields */ }

Builder for creating NullBuffers (bitmaps indicating validity/nulls).

See also

• BooleanBufferBuilder for a lower-level bitmap builder.
• Self::allocated_size for the current memory allocated by the builder.

Performance

This builder only materializes the buffer when null values (false) are appended. If you only append non-null, (true) to the builder, no buffer is allocated and build or finish return None.

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

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 set_bit(&mut self, index: usize, v: bool)

Sets a bit in the builder at index

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 NullBuffer and resets the builder.

Returns None if the builder only contains trues. Use Self::build when you don’t need to reuse this builder.

pub fn build(self) -> Option<NullBuffer>

Builds the NullBuffer without resetting the builder.

This consumes the builder. Use Self::finish to reuse it.

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.

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.