Struct Compaction 

pub struct Compaction {
    pub walked: u64,
    pub moved: u64,
    pub bytes: u64,
}

What compaction has done to a map over its life.

The write amplification of value separation, in the two parts it is actually made of. Every record the walk steps over costs a liveness probe whether it is live or not, and every live one it finds costs a copy on top of that, so a segment full of dead records and a segment full of live ones are different amounts of work for the same number of bytes. One counter cannot tell those apart, which is why there are three.

Counted here rather than in the caller because this is the only place that knows a record moved, and the numbers are wanted per store rather than per command. They never reset, including across RawMap::clear.

Fields

walked: u64

Records the walk has stepped over, live and dead together.

moved: u64

The ones that were still live and had to be copied somewhere else.

bytes: u64

What those copies came to, headers and keys included.

Trait Implementations

impl Clone for Compaction

fn clone(&self) -> Compaction

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Compaction

impl Debug for Compaction

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

Formats the value using the given formatter.

impl Default for Compaction

fn default() -> Compaction

Returns the “default value” for a type.

impl Eq for Compaction

impl PartialEq for Compaction

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Compaction