Enum FilterPushdownPhase 

pub enum FilterPushdownPhase {
    Pre,
    Post,
}

Variants

Pre

Pushdown that happens before most other optimizations. This pushdown allows static filters that do not reference any ExecutionPlans to be pushed down. Filters that reference an ExecutionPlan cannot be pushed down at this stage since the whole plan tree may be rewritten by other optimizations. Implementers are however allowed to modify the execution plan themselves during this phase, for example by returning a completely different ExecutionPlan from ExecutionPlan::handle_child_pushdown_result.

Pushdown of FilterExec into DataSourceExec is an example of a pre-pushdown. Unlike filter pushdown in the logical phase, which operates on the logical plan to push filters into the logical table scan, the Pre phase in the physical plan targets the actual physical scan, pushing filters down to specific data source implementations. For example, Parquet supports filter pushdown to reduce data read during scanning, while CSV typically does not.

Post

Pushdown that happens after most other optimizations. This stage of filter pushdown allows filters that reference an ExecutionPlan to be pushed down. Since subsequent optimizations should not change the structure of the plan tree except for calling ExecutionPlan::with_new_children (which generally preserves internal references) it is safe for references between ExecutionPlans to be established at this stage.

This phase is used to link a SortExec (with a TopK operator) or a HashJoinExec to a DataSourceExec.

Trait Implementations

impl Clone for FilterPushdownPhase

fn clone(&self) -> FilterPushdownPhase

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FilterPushdownPhase

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

Formats the value using the given formatter.

impl Display for FilterPushdownPhase

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

Formats the value using the given formatter.

impl PartialEq for FilterPushdownPhase

fn eq(&self, other: &FilterPushdownPhase) -> 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 Copy for FilterPushdownPhase

impl Eq for FilterPushdownPhase

impl StructuralPartialEq for FilterPushdownPhase