Enum MaterializationStyle 

pub enum MaterializationStyle {
    Heuristic,
    AllLate,
    AllEarly,
    AllEarlyExcept(Vec<u32>),
}

Materialization style for the scanner

This only affects columns that are not used in a filter

Early materialization will fetch the entire column and throw away the rows that are not needed. This fetches more data but uses fewer I/O requests.

Late materialization will only fetch the rows that are needed. This fetches less data but uses more I/O requests.

This parameter only affects scans. Vector search and full text search always use late materialization.

Variants

Heuristic

Heuristic-based materialization style

The default approach depends on the type of object storage. For cloud storage (e.g. S3, GCS, etc.) we only use late materialization for columns that are more than 1000 bytes in size.

For local storage we use late materialization for columns that are more than 10 bytes in size.

These values are based on experimentation and the assumption that a filter will be selecting ~0.1% of the rows in a column.

AllLate

All columns will be fetched with late materialization where possible

AllEarly

All columns will be fetched with early materialization where possible

AllEarlyExcept(Vec<u32>)

All columns will be fetched with late materialization except for the specified columns

Implementations

impl MaterializationStyle

pub fn all_early_except( columns: &[impl AsRef<str>], schema: &Schema, ) -> Result<Self>

Trait Implementations

impl Clone for MaterializationStyle

fn clone(&self) -> MaterializationStyle

Returns a duplicate of the value.

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

Performs copy-assignment from source.