lance_encoding::decoder

Trait PageScheduler

Source 
pub trait PageScheduler:
    Send
    + Sync
    + Debug {
    // Required method
    fn schedule_ranges(
        &self,
        ranges: &[Range<u64>],
        scheduler: &Arc<dyn EncodingsIo>,
        top_level_row: u64,
    ) -> BoxFuture<'static, Result<Box<dyn PrimitivePageDecoder>>>;
}
Expand description

A scheduler for single-column encodings of primitive data

The scheduler is responsible for calculating what I/O is needed for the requested rows

Instances should be stateless and Send and Sync. This is because instances can be shared in follow-up I/O tasks.

See crate::decoder for more information

Required Methods§

Source

fn schedule_ranges( &self, ranges: &[Range<u64>], scheduler: &Arc<dyn EncodingsIo>, top_level_row: u64, ) -> BoxFuture<'static, Result<Box<dyn PrimitivePageDecoder>>>

Schedules a batch of I/O to load the data needed for the requested ranges

Returns a future that will yield a decoder once the data has been loaded

§Arguments
  • range - the range of row offsets (relative to start of page) requested these must be ordered and must not overlap
  • scheduler - a scheduler to submit the I/O request to
  • top_level_row - the row offset of the top level field currently being scheduled. This can be used to assign priority to I/O requests

Implementors§