Struct SplitProjection 

pub struct SplitProjection {
    pub source: ProjectionExprs,
    pub file_indices: Vec<usize>,
    /* private fields */
}

At a high level the goal of SplitProjection is to take a ProjectionExprs meant to be applied to the table schema and split that into:

• The projection indices into the file schema (file_indices)

• The projection indices into the partition values (partition_value_indices), which pre-compute both the index into the table schema and the index into the partition values array

• A remapped projection that can be applied after the file projection is applied This remapped projection has the following properties:

  • Column indices referring to file columns are remapped to [0..file_indices.len())
  • Column indices referring to partition columns are remapped to [file_indices.len()..)

  This allows the ProjectionOpener to easily identify which columns in the remapped projection refer to partition columns and substitute them with literals from the partition values.

Fields

source: ProjectionExprs

The original projection this SplitProjection was derived from

file_indices: Vec<usize>

Column indices to read from file (public for file sources)

Implementations

impl SplitProjection

pub fn unprojected(table_schema: &TableSchema) -> Self

pub fn new(logical_file_schema: &Schema, projection: &ProjectionExprs) -> Self

Creates a new SplitProjection by splitting a projection into simple file column indices and a remainder projection that is applied after reading the file.

In other words: we get a Vec<usize> projection that is meant to be applied on top of file_schema and a remainder projection that is applied to the result of that first projection.

Here file_schema is expected to be the logical schema of the file, that is the table schema minus any partition columns. Partition columns are always expected to be at the end of the table schema. Note that file_schema is not the physical schema of the file.

Trait Implementations

impl Clone for SplitProjection

fn clone(&self) -> SplitProjection

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SplitProjection

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

Formats the value using the given formatter.