Enum Durability 

pub enum Durability {
    Fsync,
    Relaxed,
}

How much a commit promises, which is a semantic choice rather than a tuning knob.

03 §3.7 makes the log the only description of a program’s history, so “an accepted event may be lost” is a change to what the system means and not a setting. It is therefore named, defaulted to the strong option, and measured (docs/67 §67.3) — because the cost of the strong option is 38× and a number that large deserves to be visible rather than discovered.

Variants

Fsync

synchronous = FULL: every commit is on the platter before it is acknowledged.

The same promise redb and Postgres make, which is what makes them comparable.

Relaxed

synchronous = NORMAL under WAL: a commit survives a process crash and may be lost in a power loss. Not corrupted — WAL rules that out — but an acknowledged event can vanish.

Legitimate for a laptop where the log is a scratchpad, and never the default, because a weaker promise arrived at by not reading a manual is not a decision anybody made.

Trait Implementations

impl Clone for Durability

fn clone(&self) -> Durability

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Durability

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

Formats the value using the given formatter.

impl Default for Durability

fn default() -> Durability

Returns the “default value” for a type.

impl PartialEq for Durability

fn eq(&self, other: &Durability) -> 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 Durability

impl Eq for Durability

impl StructuralPartialEq for Durability