handle histogram_avg using DetectHistogramStatsOptimizer (#543)

Signed-off-by: yeya24 <[email protected]>

Author: yeya24

engine/bench_test.go

@@ -406,6 +406,14 @@ func BenchmarkNativeHistograms(b *testing.B) {
 			name:  "histogram_count with sum and rate",
 			query: `histogram_count(sum(rate(native_histogram_series[1m])))`,
 		},
+		{
+			name:  "histogram_avg",
+			query: `histogram_avg(native_histogram_series)`,
+		},
+		{
+			name:  "histogram_avg with sum and rate",
+			query: `histogram_avg(sum(rate(native_histogram_series[1m])))`,
+		},
 		{
 			name:  "histogram_quantile",
 			query: `histogram_quantile(0.9, sum(native_histogram_series))`,
@@ -414,6 +422,14 @@ func BenchmarkNativeHistograms(b *testing.B) {
 			name:  "histogram scalar binop",
 			query: `sum(native_histogram_series * 60)`,
 		},
+		{
+			name:  "histogram_stdvar",
+			query: `histogram_stdvar(native_histogram_series)`,
+		},
+		{
+			name:  "histogram_stddev",
+			query: `histogram_stddev(native_histogram_series)`,
+		},
 	}
 
 	opts := promql.EngineOpts{

engine/engine_test.go

@@ -5358,6 +5358,14 @@ histogram_sum(
 			name:  "histogram_fraction",
 			query: `histogram_fraction(0, 0.2, native_histogram_series)`,
 		},
+		{
+			name:  "histogram_stdvar",
+			query: `histogram_stdvar(native_histogram_series)`,
+		},
+		{
+			name:  "histogram_stddev",
+			query: `histogram_stddev(native_histogram_series)`,
+		},
 		{
 			name:  "lhs multiplication",
 			query: `native_histogram_series * 3`,

logicalplan/histogram_stats.go

@@ -26,7 +26,7 @@ func (d DetectHistogramStatsOptimizer) optimize(plan Node, decodeStats bool) (No
 			n.DecodeNativeHistogramStats = decodeStats
 		case *FunctionCall:
 			switch n.Func.Name {
-			case "histogram_count", "histogram_sum":
+			case "histogram_count", "histogram_sum", "histogram_avg":
 				n.Args[0], _ = d.optimize(n.Args[0], true)
 				stop = true
 				return
@@ -38,6 +38,10 @@ func (d DetectHistogramStatsOptimizer) optimize(plan Node, decodeStats bool) (No
 				n.Args[2], _ = d.optimize(n.Args[2], false)
 				stop = true
 				return
+			case "histogram_stddev", "histogram_stdvar":
+				n.Args[0], _ = d.optimize(n.Args[0], false)
+				stop = true
+				return
 			}
 		}
 	})