2 files changed, 85 insertions, 13 deletions
diff --git a/src/pkg/database/sql/convert.go b/src/pkg/database/sql/convert.go
index c04adde1fc..c0b38a2494 100644
--- a/src/pkg/database/sql/convert.go
+++ b/src/pkg/database/sql/convert.go
@@ -160,27 +160,19 @@ func convertAssign(dest, src interface{}) error {
 			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
 			reflect.Float32, reflect.Float64:
-			*d = fmt.Sprintf("%v", src)
+			*d = asString(src)
 			return nil
 		}
 	case *[]byte:
 		sv = reflect.ValueOf(src)
-		switch sv.Kind() {
-		case reflect.Bool,
-			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
-			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
-			reflect.Float32, reflect.Float64:
-			*d = []byte(fmt.Sprintf("%v", src))
+		if b, ok := asBytes(nil, sv); ok {
+			*d = b
 			return nil
 		}
 	case *RawBytes:
 		sv = reflect.ValueOf(src)
-		switch sv.Kind() {
-		case reflect.Bool,
-			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
-			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
-			reflect.Float32, reflect.Float64:
-			*d = RawBytes(fmt.Sprintf("%v", src))
+		if b, ok := asBytes([]byte(*d)[:0], sv); ok {
+			*d = RawBytes(b)
 			return nil
 		}
 	case *bool:
@@ -271,5 +263,37 @@ func asString(src interface{}) string {
 	case []byte:
 		return string(v)
 	}
+	rv := reflect.ValueOf(src)
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.FormatInt(rv.Int(), 10)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.FormatUint(rv.Uint(), 10)
+	case reflect.Float64:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 64)
+	case reflect.Float32:
+		return strconv.FormatFloat(rv.Float(), 'g', -1, 32)
+	case reflect.Bool:
+		return strconv.FormatBool(rv.Bool())
+	}
 	return fmt.Sprintf("%v", src)
 }
+
+func asBytes(buf []byte, rv reflect.Value) (b []byte, ok bool) {
+	switch rv.Kind() {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return strconv.AppendInt(buf, rv.Int(), 10), true
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return strconv.AppendUint(buf, rv.Uint(), 10), true
+	case reflect.Float32:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 32), true
+	case reflect.Float64:
+		return strconv.AppendFloat(buf, rv.Float(), 'g', -1, 64), true
+	case reflect.Bool:
+		return strconv.AppendBool(buf, rv.Bool()), true
+	case reflect.String:
+		s := rv.String()
+		return append(buf, s...), true
+	}
+	return
+}
diff --git a/src/pkg/database/sql/convert_test.go b/src/pkg/database/sql/convert_test.go
index a39c2c54fb..aa0b6f116a 100644
--- a/src/pkg/database/sql/convert_test.go
+++ b/src/pkg/database/sql/convert_test.go
@@ -279,3 +279,51 @@ func TestValueConverters(t *testing.T) {
 		}
 	}
 }
+
+// Tests that assigning to RawBytes doesn't allocate (and also works).
+func TestRawBytesAllocs(t *testing.T) {
+	buf := make(RawBytes, 10)
+	test := func(name string, in interface{}, want string) {
+		if err := convertAssign(&buf, in); err != nil {
+			t.Fatalf("%s: convertAssign = %v", name, err)
+		}
+		match := len(buf) == len(want)
+		if match {
+			for i, b := range buf {
+				if want[i] != b {
+					match = false
+					break
+				}
+			}
+		}
+		if !match {
+			t.Fatalf("%s: got %q (len %d); want %q (len %d)", name, buf, len(buf), want, len(want))
+		}
+	}
+	n := testing.AllocsPerRun(100, func() {
+		test("uint64", uint64(12345678), "12345678")
+		test("uint32", uint32(1234), "1234")
+		test("uint16", uint16(12), "12")
+		test("uint8", uint8(1), "1")
+		test("uint", uint(123), "123")
+		test("int", int(123), "123")
+		test("int8", int8(1), "1")
+		test("int16", int16(12), "12")
+		test("int32", int32(1234), "1234")
+		test("int64", int64(12345678), "12345678")
+		test("float32", float32(1.5), "1.5")
+		test("float64", float64(64), "64")
+		test("bool", false, "false")
+	})
+	if n > 0.5 {
+		t.Fatalf("allocs = %v; want 0", n)
+	}
+
+	// This one involves a convT2E allocation, string -> interface{}
+	n = testing.AllocsPerRun(100, func() {
+		test("string", "foo", "foo")
+	})
+	if n > 1.5 {
+		t.Fatalf("allocs = %v; want max 1", n)
+	}
+}