Struct ColumnarPolicy 

pub struct ColumnarPolicy { /* private fields */ }

Adaptive gate for the typed columnar chunk layout (cross-query shared).

Uses accumulated columnar hit/miss counts with a hit-rate threshold and a minimum sample count. Below min_samples the policy defaults to columnar (matching the historical default-on behavior, so there is no performance regression at startup).

Thread Safety

All counters are Relaxed atomics; should_use_columnar never blocks. The policy values are only mutated between queries (when merging per-query snapshots), so reads within a single query are stable and a query never flips layout mid-flight.

Implementations

impl ColumnarPolicy

pub fn new(threshold: f64, min_samples: u64) -> Self

Create a policy with explicit threshold and minimum sample count.

pub fn should_use_columnar(&self) -> bool

Decide whether the typed columnar path should be used.

Returns true while the sample count is below min_samples (default-on), and thereafter when the cumulative hit rate stays at or above the threshold.

pub fn should_use_columnar_with( &self, query_override: QueryColumnarOverride, ) -> bool

Decide with a per-query override applied first.

A forced override wins over the adaptive decision so a single query can be pinned without mutating the shared counters; otherwise the shared threshold logic applies unchanged.

pub fn record(&self, hit: bool)

Record a single hit / miss decision (used by tests and single-thread simulations).

pub fn record_hit(&self)

Record one columnar fast-path hit.

pub fn record_miss(&self)

Record one row-wise fallback.

pub fn merge(&self, hits: u64, misses: u64)

Merge a per-query columnar snapshot into the shared counters.

Called once per completed query (materialized and streaming paths); hits / misses are the deltas of that query’s crate::executor::streaming::runtime::ColumnarStats.

pub fn snapshot(&self) -> (u64, u64)

Point-in-time snapshot of (hits, misses).

pub fn hit_rate(&self) -> f64

Cumulative hit rate over all recorded samples (1.0 when empty).

pub fn threshold(&self) -> f64

The configured hit-rate threshold.

pub fn min_samples(&self) -> u64

The configured minimum sample count.

Trait Implementations

impl Debug for ColumnarPolicy

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

Formats the value using the given formatter.

impl Default for ColumnarPolicy

fn default() -> Self

Returns the “default value” for a type.