Enum WriterEncoding 

pub enum WriterEncoding {
    Raw,
    Adaptive,
    Fixed(WriterTransform),
}

The writer-side encoding policy.

Raw is the default and preserves the plain-layout, raw-transform stream choices, so a file written without asking for anything else is byte-for-byte what earlier versions of this writer produced. Adaptive profiles each dense stream once and selects a specialized v0.2 layout only after the complete stored representation — every stream, its descriptor, its padding, and its compressed size — beats the raw baseline by at least the larger of 64 bytes or one percent. Selection is deterministic and depends only on the block’s values, never on how those rows were divided among crate::Writer::append calls.

Fixed applies one requested transform or layout to every dense column value stream. It prices nothing and never falls back: crate::Writer::create returns an error for a transform this writer does not offer for one of the schema’s logical types, and a block whose values the transform cannot describe fails when it is published.

The offered set is exactly the candidate set Adaptive would have priced, so a fixed file is always a shape adaptive could also have written. That set is narrower than what the format permits: a timestamp64 column offers raw, frame of reference, delta, and delta-of-delta and nothing else, so Fixed(WriterTransform::Dictionary) is refused for one even though a dictionary timestamp64 column is a legal v0.2 shape.

Validity streams stay raw under Fixed, because they are independent boolean streams that the requested value transform does not describe.

Adaptive profiling holds the block’s dense values a second time while it prices candidates, so it raises peak writer memory by a small multiple of WriterOptions::byte_block_target. Lower that target to lower the peak.

Variants

Raw

Plain layout with the raw transform for every stream.

Adaptive

Deterministically choose profitable v0.2 layouts and transforms.

Fixed(WriterTransform)

Apply one transform/layout to every compatible column without profiling.

Trait Implementations

impl Clone for WriterEncoding

fn clone(&self) -> WriterEncoding

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for WriterEncoding

impl Debug for WriterEncoding

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

Formats the value using the given formatter.

impl Default for WriterEncoding

fn default() -> WriterEncoding

Returns the “default value” for a type.

impl Eq for WriterEncoding

impl PartialEq for WriterEncoding

fn eq(&self, other: &WriterEncoding) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for WriterEncoding