1 files changed, 33 insertions, 2 deletions
diff --git a/postgres/postgres.go b/postgres/postgres.go
index 3a5221e..5333f8d 100644
--- a/postgres/postgres.go
+++ b/postgres/postgres.go
@@ -3,6 +3,8 @@ package postgres
 import (
 	"encoding/json"
 	"fmt"
+	"math"
+	"time"
 
 	"github.com/jmoiron/sqlx"
 	_ "github.com/lib/pq"
@@ -139,10 +141,39 @@ func (db *DB) Analyze(query string) ([]*Explain, error) {
 	}
 
 	var exp []*Explain
-	if err := json.Unmarshal([]byte(plan.Plan), &exp); err != nil {
-		// if err := json.Unmarshal([]byte(testPlan), &a); err != nil {
+	// if err := json.Unmarshal([]byte(plan.Plan), &exp); err != nil {
+	if err := json.Unmarshal([]byte(testPlan), &exp); err != nil {
 		return nil, fmt.Errorf("could not unmarshal plan: %v", err)
 	}
 
 	return exp, nil
 }
+
+func (p *Plan) EffectiveTotalTime() time.Duration {
+	var childTime time.Duration
+	for _, p := range p.Plans {
+		childTime = childTime + f2d(p.ActualTotalTime)
+	}
+	return f2d(p.ActualTotalTime) - childTime
+}
+
+func (p *Plan) EstimateWrongness() (string, int) {
+	plan, actual := float64(p.PlanRows), float64(p.ActualRows)
+	bigger, smaller := math.Max(plan, actual), math.Min(plan, actual)
+	ratio := int(bigger / smaller)
+	if plan > actual {
+		return "over", ratio
+	}
+	return "under", ratio
+}
+
+func (p *Plan) IsBadEstimate() bool {
+	_, ratio := p.EstimateWrongness()
+	return ratio >= 100
+}
+
+func f2d(f float32) time.Duration {
+	// f is in milliseconds, multiply by 1k to get microseconds
+	// (thousandths of milliseconds)
+	return time.Duration(int(f)*1000) * time.Microsecond
+}