Try a single outer struct with all fields embedded

pkg/services/ngalert/api/api_ruler_validation.go

@@ -110,8 +110,7 @@ func validateRuleNode(
 		ExecErrState:    errorState,
 		// Recording Rule fields will be implemented in the future.
 		// For now, no rules can be recording rules. So, we force these to be empty.
-		Record:     "",
-		RecordFrom: "",
+		Record: nil,
 	}
 
 	if ruleNode.GrafanaManagedAlert.NotificationSettings != nil {

pkg/services/ngalert/api/api_ruler_validation_test.go

@@ -339,8 +339,7 @@ func TestValidateRuleNode_NoUID(t *testing.T) {
 				require.Equal(t, time.Duration(*api.ApiRuleNode.For), alert.For)
 				require.Equal(t, api.ApiRuleNode.Annotations, alert.Annotations)
 				require.Equal(t, api.ApiRuleNode.Labels, alert.Labels)
-				require.Empty(t, alert.Record)
-				require.Empty(t, alert.RecordFrom)
+				require.Nil(t, alert.Record)
 			},
 		},
 		{

pkg/services/ngalert/api/compat.go

@@ -33,8 +33,7 @@ func AlertRuleFromProvisionedAlertRule(a definitions.ProvisionedAlertRule) (mode
 		NotificationSettings: NotificationSettingsFromAlertRuleNotificationSettings(a.NotificationSettings),
 		// Recording Rule fields will be implemented in the future.
 		// For now, no rules can be recording rules. So, we force these to be empty.
-		Record:     "",
-		RecordFrom: "",
+		Record: nil,
 	}, nil
 }
 

pkg/services/ngalert/models/alert_rule.go

@@ -5,14 +5,17 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"hash/fnv"
 	"sort"
 	"strconv"
 	"strings"
 	"time"
+	"unsafe"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/go-cmp/cmp/cmpopts"
 	alertingModels "github.com/grafana/alerting/models"
+	"github.com/grafana/grafana-plugin-sdk-go/data"
 
 	"github.com/grafana/grafana/pkg/services/quota"
 	"github.com/grafana/grafana/pkg/setting"
@@ -239,9 +242,8 @@ type AlertRule struct {
 	DashboardUID    *string `xorm:"dashboard_uid"`
 	PanelID         *int64  `xorm:"panel_id"`
 	RuleGroup       string
-	RuleGroupIndex  int `xorm:"rule_group_idx"`
-	Record          string
-	RecordFrom      string
+	RuleGroupIndex  int     `xorm:"rule_group_idx"`
+	Record          *Record `xorm:"text null 'record'"`
 	NoDataState     NoDataState
 	ExecErrState    ExecutionErrorState
 	// ideally this field should have been apimodels.ApiDuration
@@ -516,10 +518,7 @@ func (alertRule *AlertRule) ValidateAlertRule(cfg setting.UnifiedAlertingSetting
 		}
 	}
 
-	if alertRule.Record != "" {
-		return fmt.Errorf("%w: storing recording rules is not yet allowed", ErrAlertRuleFailedValidation)
-	}
-	if alertRule.RecordFrom != "" {
+	if alertRule.Record != nil {
 		return fmt.Errorf("%w: storing recording rules is not yet allowed", ErrAlertRuleFailedValidation)
 	}
 
@@ -570,8 +569,7 @@ type AlertRuleVersion struct {
 	Condition       string
 	Data            []AlertQuery
 	IntervalSeconds int64
-	Record          string
-	RecordFrom      string
+	Record          *Record `xorm:"text null 'record'"`
 	NoDataState     NoDataState
 	ExecErrState    ExecutionErrorState
 	// ideally this field should have been apimodels.ApiDuration
@@ -768,3 +766,26 @@ func GroupByAlertRuleGroupKey(rules []*AlertRule) map[AlertRuleGroupKey]RulesGro
 	}
 	return result
 }
+
+// Record contains mapping information for Recording Rules.
+type Record struct {
+	// Metric indicates a metric name to send results to.
+	Metric string
+	// From contains a query RefID, indicating which expression node is the output of the recording rule.
+	From string
+}
+
+func (r *Record) Fingerprint() data.Fingerprint {
+	h := fnv.New64()
+
+	writeString := func(s string) {
+		// save on extra slice allocation when string is converted to bytes.
+		_, _ = h.Write(unsafe.Slice(unsafe.StringData(s), len(s))) //nolint:gosec
+		// ignore errors returned by Write method because fnv never returns them.
+		_, _ = h.Write([]byte{255}) // use an invalid utf-8 sequence as separator
+	}
+
+	writeString(r.Metric)
+	writeString(r.From)
+	return data.Fingerprint(h.Sum64())
+}

pkg/services/ngalert/models/alert_rule_test.go

@@ -512,13 +512,6 @@ func TestDiff(t *testing.T) {
 			assert.Equal(t, rule2.Record, diff[0].Right.String())
 			difCnt++
 		}
-		if rule1.RecordFrom != rule2.RecordFrom {
-			diff := diffs.GetDiffsForField("RecordFrom")
-			assert.Len(t, diff, 1)
-			assert.Equal(t, rule1.RecordFrom, diff[0].Left.String())
-			assert.Equal(t, rule2.RecordFrom, diff[0].Right.String())
-			difCnt++
-		}
 
 		require.Lenf(t, diffs, difCnt, "Got some unexpected diffs. Either add to ignore or add assert to it")
 

pkg/services/ngalert/schedule/registry.go

@@ -311,7 +311,10 @@ func (r ruleWithFolder) Fingerprint() fingerprint {
 	writeInt(int64(rule.RuleGroupIndex))
 	writeString(string(rule.NoDataState))
 	writeString(string(rule.ExecErrState))
-	writeString(rule.Record)
-	writeString(rule.RecordFrom)
+	if rule.Record != nil {
+		binary.LittleEndian.PutUint64(tmp, uint64(rule.Record.Fingerprint()))
+		writeBytes(tmp)
+	}
+
 	return fingerprint(sum.Sum64())
 }

pkg/services/ngalert/schedule/registry_test.go

@@ -192,8 +192,7 @@ func TestRuleWithFolderFingerprint(t *testing.T) {
 			RuleGroupIndex:  1,
 			NoDataState:     "test-nodata",
 			ExecErrState:    "test-err",
-			Record:          "my_metric",
-			RecordFrom:      "A",
+			Record:          &models.Record{Metric: "my_metric", From: "A"},
 			For:             12,
 			Annotations: map[string]string{
 				"key-annotation": "value-annotation",
@@ -232,8 +231,7 @@ func TestRuleWithFolderFingerprint(t *testing.T) {
 			RuleGroupIndex:  22,
 			NoDataState:     "test-nodata2",
 			ExecErrState:    "test-err2",
-			Record:          "my_metric2",
-			RecordFrom:      "B",
+			Record:          &models.Record{Metric: "my_metric2", From: "B"},
 			For:             1141,
 			Annotations: map[string]string{
 				"key-annotation2": "value-annotation",

pkg/services/ngalert/store/alert_rule.go

@@ -162,7 +162,6 @@ func (st DBstore) InsertAlertRules(ctx context.Context, rules []ngmodels.AlertRu
 				Annotations:          r.Annotations,
 				Labels:               r.Labels,
 				Record:               r.Record,
-				RecordFrom:           r.RecordFrom,
 				NotificationSettings: r.NotificationSettings,
 			})
 		}
@@ -241,7 +240,6 @@ func (st DBstore) UpdateAlertRules(ctx context.Context, rules []ngmodels.UpdateR
 				NoDataState:          r.New.NoDataState,
 				ExecErrState:         r.New.ExecErrState,
 				Record:               r.New.Record,
-				RecordFrom:           r.New.RecordFrom,
 				For:                  r.New.For,
 				Annotations:          r.New.Annotations,
 				Labels:               r.New.Labels,

pkg/services/ngalert/store/alert_rule_test.go

@@ -643,10 +643,9 @@ func TestIntegrationInsertAlertRules(t *testing.T) {
 		require.Truef(t, found, "Rule with key %#v was not found in database", keyWithID)
 	}
 
-	t.Run("inserted alerting rules should have default recording rule fields on model", func(t *testing.T) {
+	t.Run("inserted alerting rules should have nil recording rule fields on model", func(t *testing.T) {
 		for _, rule := range dbRules {
-			require.Empty(t, rule.Record)
-			require.Empty(t, rule.RecordFrom)
+			require.Nil(t, rule.Record)
 		}
 	})
 

pkg/services/sqlstore/migrations/ualert/recording_rules_mig.go

@@ -6,33 +6,13 @@ import "github.com/grafana/grafana/pkg/services/sqlstore/migrator"
 func AddRecordingRuleColumns(mg *migrator.Migrator) {
 	mg.AddMigration("add record column to alert_rule table", migrator.NewAddColumnMigration(migrator.Table{Name: "alert_rule"}, &migrator.Column{
 		Name:     "record",
-		Type:     migrator.DB_NVarchar,
-		Length:   DefaultFieldMaxLength,
-		Default:  "''",
-		Nullable: false,
+		Type:     migrator.DB_Text, // Text, to allow for future growth, as this contains a JSON-ified struct.
+		Nullable: true,
 	}))
 
 	mg.AddMigration("add record column to alert_rule_version table", migrator.NewAddColumnMigration(migrator.Table{Name: "alert_rule_version"}, &migrator.Column{
 		Name:     "record",
-		Type:     migrator.DB_NVarchar,
-		Length:   DefaultFieldMaxLength,
-		Default:  "''",
-		Nullable: false,
-	}))
-
-	mg.AddMigration("add record_from column to alert_rule table", migrator.NewAddColumnMigration(migrator.Table{Name: "alert_rule"}, &migrator.Column{
-		Name:     "record_from",
-		Type:     migrator.DB_NVarchar,
-		Length:   DefaultFieldMaxLength,
-		Default:  "''",
-		Nullable: false,
-	}))
-
-	mg.AddMigration("add record_from column to alert_rule_version table", migrator.NewAddColumnMigration(migrator.Table{Name: "alert_rule_version"}, &migrator.Column{
-		Name:     "record_from",
-		Type:     migrator.DB_NVarchar,
-		Length:   DefaultFieldMaxLength,
-		Default:  "''",
-		Nullable: false,
+		Type:     migrator.DB_Text,
+		Nullable: true,
 	}))
 }