Struct ExpressionEvaluatorMetrics 

pub struct ExpressionEvaluatorMetrics { /* private fields */ }

Tracks evaluation time for a sequence of expressions.

Example

Given SQL query: EXPLAIN ANALYZE SELECT a+1, pow(a,2) FROM generate_series(1, 1000000) as t1(a)

This struct holds two time metrics for the projection expressions a+1 and pow(a,2), respectively.

The output reads: ProjectionExec: expr=[a@0 + 1 as t1.a + Int64(1), power(CAST(a@0 AS Float64), 2) as pow(t1.a,Int64(2))], metrics=[... expr_0_eval_time=9.23ms, expr_1_eval_time=32.35ms...]

Implementations

impl ExpressionEvaluatorMetrics

pub fn new<T>( metrics: &ExecutionPlanMetricsSet, partition: usize, expression_labels: impl IntoIterator<Item = T>, ) -> Self

where T: Into<String>,

Create metrics for a collection of expressions.

Args

• metrics: see MetricBuilder for details.
• partition: see MetricBuilder for details.
• expression_labels: unique identifier for each metric, so that the metric can get aggregated across multiple partitions. It is not the name showed in the EXPLAIN ANALYZE, the metric name will be expr_{idx}_eval_time according to the expression order.

pub fn scoped_timer(&self, index: usize) -> Option<ScopedTimerGuard<'_>>

Returns a timer guard for the expression at index, if present.

pub fn len(&self) -> usize

The number of tracked expressions.

pub fn is_empty(&self) -> bool

True when no expressions are tracked.

Trait Implementations

impl Clone for ExpressionEvaluatorMetrics

fn clone(&self) -> ExpressionEvaluatorMetrics

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExpressionEvaluatorMetrics

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

Formats the value using the given formatter.