Struct GroupCommitSettings 

pub struct GroupCommitSettings {
    pub min_batch_size: usize,
    pub max_batch_size: usize,
    pub max_wait_us: u64,
    pub fsync_latency_us: u64,
}

Group commit settings - mirrors SQLite’s WAL mode tuning

Performance Model

Without group commit: Throughput = 1 / L_fsync ≈ 200 commits/sec (L=5ms) With group commit (batch size K): Throughput = K / L_fsync = K × 200 commits/sec

For K=100: 20,000 commits/sec (100× speedup)

SQLite Comparison

Setting	SQLite Equivalent
batch_size = 1	PRAGMA synchronous = FULL
batch_size = 100	WAL mode with batching
max_wait_us = 0	No delay, immediate flush
max_wait_us = 10000	Up to 10ms delay for batch

Fields

min_batch_size: usize

Minimum batch size before flush (default: 1)

max_batch_size: usize

Maximum batch size (default: 1000)

max_wait_us: u64

Maximum wait time before flush in microseconds (default: 10000 = 10ms)

fsync_latency_us: u64

Expected fsync latency in microseconds (for adaptive sizing)

Implementations

impl GroupCommitSettings

pub fn high_throughput() -> Self

High throughput preset - maximizes batching

pub fn low_latency() -> Self

Low latency preset - minimal batching

pub fn optimal_batch_size(&self, arrival_rate: f64, wait_cost: f64) -> usize

Calculate optimal batch size using Little’s Law

N* = sqrt(2 × L_fsync × λ / C_wait)

Arguments

• arrival_rate - Operations per second
• wait_cost - Cost coefficient for waiting (0.0-1.0)

Trait Implementations

impl Clone for GroupCommitSettings

fn clone(&self) -> GroupCommitSettings

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GroupCommitSettings

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

Formats the value using the given formatter.

impl Default for GroupCommitSettings

fn default() -> Self

Returns the “default value” for a type.