feat: add PlanMetrics to extract EXPLAIN ANALYZE performance data

Author: radim

regresql/analyze_types.go

@@ -126,8 +126,47 @@ type (
 		WorstOver  *RowEstimate  `json:"worst_overestimate,omitempty"`
 		WorstUnder *RowEstimate  `json:"worst_underestimate,omitempty"`
 	}
+
+	// PlanMetrics contains performance metrics from EXPLAIN ANALYZE.
+	// Timing fields require ANALYZE, buffer fields require BUFFERS option.
+	PlanMetrics struct {
+		TotalCost       float64 `json:"total_cost"`
+		ExecutionTimeMs float64 `json:"execution_time_ms"`
+		PlanningTimeMs  float64 `json:"planning_time_ms"`
+		ActualRows      int64   `json:"actual_rows"`
+
+		// Buffer stats (root node only)
+		SharedHitBlocks   int64 `json:"shared_hit_blocks"`
+		SharedReadBlocks  int64 `json:"shared_read_blocks"`
+		LocalHitBlocks    int64 `json:"local_hit_blocks"`
+		LocalReadBlocks   int64 `json:"local_read_blocks"`
+		TempReadBlocks    int64 `json:"temp_read_blocks"`
+		TempWrittenBlocks int64 `json:"temp_written_blocks"`
+		TotalBuffers      int64 `json:"total_buffers"`
+		IOReadTimeMs      float64 `json:"io_read_time_ms"`
+		IOWriteTimeMs     float64 `json:"io_write_time_ms"`
+	}
 )
 
+// ExtractMetrics extracts performance metrics from the root plan node.
+func (e *ExplainOutput) ExtractMetrics() PlanMetrics {
+	return PlanMetrics{
+		TotalCost:         e.Plan.TotalCost,
+		ExecutionTimeMs:   e.ExecutionTime,
+		PlanningTimeMs:    e.PlanningTime,
+		ActualRows:        e.Plan.ActualRows,
+		SharedHitBlocks:   e.Plan.SharedHitBlocks,
+		SharedReadBlocks:  e.Plan.SharedReadBlocks,
+		LocalHitBlocks:    e.Plan.LocalHitBlocks,
+		LocalReadBlocks:   e.Plan.LocalReadBlocks,
+		TempReadBlocks:    e.Plan.TempReadBlocks,
+		TempWrittenBlocks: e.Plan.TempWrittenBlocks,
+		TotalBuffers:      e.Plan.SharedHitBlocks + e.Plan.SharedReadBlocks,
+		IOReadTimeMs:      e.Plan.IOReadTime,
+		IOWriteTimeMs:     e.Plan.IOWriteTime,
+	}
+}
+
 // GetBufferStats returns buffer statistics for a plan node
 func (n *PlanNode) GetBufferStats() BufferStats {
 	return BufferStats{

regresql/library.go

@@ -29,6 +29,9 @@ type (
 		PlanChanged     bool
 		PlanRegressions []PlanRegression
 		PlanWarnings    []PlanWarning
+
+		// Metrics from EXPLAIN ANALYZE (nil if ANALYZE not used or on error)
+		Metrics *PlanMetrics
 	}
 )
 
@@ -122,6 +125,12 @@ func (p *Plan) CompareCostsData(db *sql.DB, baselines []Baseline, thresholdPerce
 			PercentIncrease: percentIncrease,
 		}
 
+		// Only populate metrics when ANALYZE was used
+		if explainPlan.ExecutionTime > 0 {
+			metrics := explainPlan.ExtractMetrics()
+			result.Metrics = &metrics
+		}
+
 		if baselines[i].PlanSignature != nil {
 			currentSig := ExtractPlanSignatureFromNode(&explainPlan.Plan)
 			result.PlanChanged = HasPlanChanged(baselines[i].PlanSignature, currentSig)