Struct PlanObservation 

pub struct PlanObservation {
    pub template_hash: String,
    pub plan_fingerprint: String,
    pub features: CorrectionFeatures,
    pub actual_rows: u64,
    pub latency_ms: Option<f64>,
}

An observation captured together with the plan-shape features the corrector will be handed at inference time.

Why this exists alongside Observation

Observation records only est_rows and actual_rows. Training from it forces the trainer to synthesise a feature vector with baseline_estimate set and the other six slots zeroed — while at inference time an adapter fills all seven. A tree model never splits on a feature that was constant during training, so six of the seven features are dead weight and the corrector is effectively one-dimensional. That is a silent train/serve skew, not a crash, which is why it survived so long.

PlanObservation closes it by recording what the corrector will actually see. Prefer it for anything that will be trained on.

Examples

use samkhya_core::feedback::PlanObservation;
use samkhya_core::residual::CorrectionFeatures;

let obs = PlanObservation {
    template_hash: "q7".into(),
    plan_fingerprint: "hash-join#1".into(),
    features: CorrectionFeatures { baseline_estimate: 10, ..Default::default() },
    actual_rows: 100,
    latency_ms: None,
};
// 10x under-estimate.
assert!((obs.q_error() - 10.0).abs() < 1e-9);

Fields

template_hash: String

plan_fingerprint: String

features: CorrectionFeatures

The feature vector the corrector saw, including baseline_estimate.

actual_rows: u64

latency_ms: Option<f64>

Implementations

impl PlanObservation

pub fn q_error(&self) -> f64

Multiplicative q-error against the baseline estimate. f64::INFINITY when either side is zero, matching Observation::q_error.

pub fn to_observation(&self) -> Observation

Reduce to the legacy shape, discarding the plan features.

Trait Implementations

impl Clone for PlanObservation

fn clone(&self) -> PlanObservation

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PlanObservation

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for PlanObservation

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for PlanObservation

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for PlanObservation

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for PlanObservation