Struct MappedTable 

pub struct MappedTable {
    pub batches: Vec<RecordBatch>,
    mapping: Range<usize>,
}

A table read straight out of its mapping.

The RecordBatch buffers point into the mmap; the mapping is kept alive by the Arc that every Buffer holds, so MappedTable can be dropped while batches derived from it are still in use.

Fields

batches: Vec<RecordBatch>

mapping: Range<usize>

Address range of the mapping, so the zero-copy property can be asserted rather than assumed.

Implementations

impl MappedTable

pub fn zero_copy_ratio(&self) -> (usize, usize)

(buffers_pointing_into_the_mapping, buffers_total).

Walks every buffer of every column including child data, so a partially copied nested array shows up. require_alignment(true) should already make a copy impossible; this is the assertion that says so out loud.

A cold block (see compact) reports 0/n on purpose: decompression has to allocate. Only the hot tier is held to inside == total.