fix: configurable comparison mode (auto/cost/buffers)

Author: radim

regresql/config.go

@@ -21,6 +21,7 @@ type (
 
 	AnalyzeConfig struct {
 		Enabled         bool    `yaml:"enabled"`
+		Comparison      string  `yaml:"comparison,omitempty"`       // "auto" | "cost" | "buffers"
 		BufferThreshold float64 `yaml:"buffer_threshold,omitempty"` // default: 2.0
 		CostThreshold   float64 `yaml:"cost_threshold,omitempty"`   // default: 10.0
 	}
@@ -181,16 +182,21 @@ func GetAnalyzeConfig() *AnalyzeConfig {
 	if cachedConfig == nil || cachedConfig.Analyze == nil {
 		return &AnalyzeConfig{
 			Enabled:         false,
+			Comparison:      "auto",
 			BufferThreshold: 2.0,
 			CostThreshold:   10.0,
 		}
 	}
 	cfg := cachedConfig.Analyze
 	result := &AnalyzeConfig{
 		Enabled:         cfg.Enabled,
+		Comparison:      cfg.Comparison,
 		BufferThreshold: cfg.BufferThreshold,
 		CostThreshold:   cfg.CostThreshold,
 	}
+	if result.Comparison == "" {
+		result.Comparison = "auto"
+	}
 	if result.BufferThreshold == 0 {
 		result.BufferThreshold = 2.0
 	}
@@ -211,3 +217,7 @@ func GetBufferThreshold() float64 {
 func GetCostThreshold() float64 {
 	return GetAnalyzeConfig().CostThreshold
 }
+
+func GetComparisonMode() string {
+	return GetAnalyzeConfig().Comparison
+}

regresql/tap.go

@@ -208,7 +208,19 @@ func (p *Plan) compareBaseline(baselineDir, bindingName string, bindings map[str
 		return result
 	}
 
-	useBufferComparison := baseline.AnalyzeMode && baseline.Buffers != nil
+	// Warn if analyze.enabled but baseline lacks buffer data
+	if IsAnalyzeEnabled() && !baseline.AnalyzeMode {
+		fmt.Fprintf(os.Stderr, "Warning: analyze.enabled=true but baseline '%s' lacks buffer data\n", baselinePath)
+	}
+
+	useBufferComparison, err := getComparisonMode(baseline, baselinePath)
+	if err != nil {
+		result.Status = "failed"
+		result.Error = err.Error()
+		result.Duration = time.Since(start).Seconds()
+		return result
+	}
+
 	explainPlan, err := p.runExplainWithMode(q, bindings, useBufferComparison)
 	if err != nil {
 		result.Status = "failed"
@@ -317,3 +329,20 @@ func hasCriticalRegression(regressions []PlanRegression) bool {
 	}
 	return false
 }
+
+func getComparisonMode(baseline *Baseline, baselinePath string) (bool, error) {
+	mode := GetComparisonMode()
+	hasBuffers := baseline.AnalyzeMode && baseline.Buffers != nil
+
+	switch mode {
+	case "buffers":
+		if !hasBuffers {
+			return false, fmt.Errorf("comparison: buffers requires baseline with buffer data - regenerate '%s' with --analyze", baselinePath)
+		}
+		return true, nil
+	case "cost":
+		return false, nil
+	default: // "auto"
+		return hasBuffers, nil
+	}
+}