Enum ParallelStrategy

pub enum ParallelStrategy {
    None,
    Columns,
    RowGroups,
    Prefiltered,
    Auto,
}

Available on crate feature parquet only.

Variants

None

Don’t parallelize

Columns

Parallelize over the columns

RowGroups

Parallelize over the row groups

Prefiltered

First evaluates the pushed-down predicates in parallel and determines a mask of which rows to read. Then, it parallelizes over both the columns and the row groups while filtering out rows that do not need to be read. This can provide significant speedups for large files (i.e. many row-groups) with a predicate that filters clustered rows or filters heavily. In other cases, this may slow down the scan compared other strategies.

If no predicate is given, this falls back to back to ParallelStrategy::Auto.

Auto

Automatically determine over which unit to parallelize This will choose the most occurring unit.

Trait Implementations

impl Clone for ParallelStrategy

fn clone(&self) -> ParallelStrategy

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for ParallelStrategy

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

Formats the value using the given formatter.

impl Default for ParallelStrategy

fn default() -> ParallelStrategy

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ParallelStrategy

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for ParallelStrategy

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ParallelStrategy

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for ParallelStrategy

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for ParallelStrategy

impl Eq for ParallelStrategy

impl StructuralPartialEq for ParallelStrategy