fix(query sharding): Generalize avg -> sum/count sharding using existing binop mapper (#12599)

pkg/logql/shardmapper.go

@@ -240,33 +240,21 @@ func (m ShardMapper) mapVectorAggregationExpr(expr *syntax.VectorAggregationExpr
 
 		case syntax.OpTypeAvg:
 			// avg(x) -> sum(x)/count(x), which is parallelizable
-			lhs, lhsBytesPerShard, err := m.mapVectorAggregationExpr(&syntax.VectorAggregationExpr{
-				Left:      expr.Left,
-				Grouping:  expr.Grouping,
-				Operation: syntax.OpTypeSum,
-			}, r, false)
-			if err != nil {
-				return nil, 0, err
-			}
-
-			rhs, rhsBytesPerShard, err := m.mapVectorAggregationExpr(&syntax.VectorAggregationExpr{
-				Left:      expr.Left,
-				Grouping:  expr.Grouping,
-				Operation: syntax.OpTypeCount,
-			}, r, false)
-			if err != nil {
-				return nil, 0, err
+			binOp := &syntax.BinOpExpr{
+				SampleExpr: &syntax.VectorAggregationExpr{
+					Left:      expr.Left,
+					Grouping:  expr.Grouping,
+					Operation: syntax.OpTypeSum,
+				},
+				RHS: &syntax.VectorAggregationExpr{
+					Left:      expr.Left,
+					Grouping:  expr.Grouping,
+					Operation: syntax.OpTypeCount,
+				},
+				Op: syntax.OpTypeDiv,
 			}
 
-			// We take the maximum bytes per shard of both sides of the operation
-			bytesPerShard := uint64(max(int(lhsBytesPerShard), int(rhsBytesPerShard)))
-
-			return &syntax.BinOpExpr{
-				SampleExpr: lhs,
-				RHS:        rhs,
-				Op:         syntax.OpTypeDiv,
-			}, bytesPerShard, nil
-
+			return m.mapBinOpExpr(binOp, r, topLevel)
 		case syntax.OpTypeCount:
 			if syntax.ReducesLabels(expr.Left) {
 				// skip sharding optimizations at this level. If labels are reduced,

pkg/logql/shardmapper_test.go

@@ -231,6 +231,18 @@ func TestMappingStrings(t *testing.T) {
 				)
 			)`,
 		},
+		{
+			in: `avg by(foo_extracted) (quantile_over_time(0.95, {foo="baz"} | logfmt | unwrap foo_extracted | __error__="" [5m]))`,
+			out: `(
+               sum by (foo_extracted) (
+                   downstream<sumby(foo_extracted)(quantile_over_time(0.95,{foo="baz"}|logfmt|unwrapfoo_extracted|__error__=""[5m])),shard=0_of_2>++downstream<sumby(foo_extracted)(quantile_over_time(0.95,{foo="baz"}|logfmt|unwrapfoo_extracted|__error__=""[5m])),shard=1_of_2>
+               )
+               / 
+               sum by (foo_extracted) (
+                   downstream<countby(foo_extracted)(quantile_over_time(0.95,{foo="baz"}|logfmt|unwrapfoo_extracted|__error__=""[5m])),shard=0_of_2>++downstream<countby(foo_extracted)(quantile_over_time(0.95,{foo="baz"}|logfmt|unwrapfoo_extracted|__error__=""[5m])),shard=1_of_2>
+               )
+            )`,
+		},
 		{
 			in: `count(rate({foo="bar"} | json | keep foo [5m]))`,
 			out: `count(
@@ -283,12 +295,12 @@ func TestMappingStrings(t *testing.T) {
 		},
 		{
 			in: `sum without (a) (
-		  			label_replace(
-		    			sum without (b) (
-		      				rate({foo="bar"}[5m])
-		    			),
-		    			"baz", "buz", "foo", "(.*)"
-		  			)
+		 			label_replace(
+		   			sum without (b) (
+		     				rate({foo="bar"}[5m])
+		   			),
+		   			"baz", "buz", "foo", "(.*)"
+		 			)
 				)`,
 			out: `sum without(a) (
 					label_replace(