restoreccl: allow restoring system users without user ids

Release note: None

pkg/ccl/backupccl/backup_test.go

@@ -9395,7 +9395,6 @@ func TestExcludeDataFromBackupDoesNotHoldupGC(t *testing.T) {
 func TestBackupRestoreSystemUsers(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
-	skip.WithIssue(t, 78963)
 
 	sqlDB, tempDir, cleanupFn := createEmptyCluster(t, singleNode)
 	_, sqlDBRestore, cleanupEmptyCluster := backupRestoreTestSetupEmpty(t, singleNode, tempDir, InitManualReplication, base.TestClusterArgs{})
@@ -9454,16 +9453,20 @@ func TestBackupRestoreSystemUsers(t *testing.T) {
 
 	_, sqlDBRestore1, cleanupEmptyCluster1 := backupRestoreTestSetupEmpty(t, singleNode, tempDir, InitManualReplication, base.TestClusterArgs{})
 	defer cleanupEmptyCluster1()
-	t.Run("restore-from-backup-with-no-system-role-members", func(t *testing.T) {
+	t.Run("restore-from-backup-with-system-role-members", func(t *testing.T) {
+		// testuser should take ID 101. The restored users originally have no ID
+		// but should be updated to have IDs 102 and so on.
+		sqlDBRestore1.Exec(t, `CREATE USER testuser`)
 		sqlDBRestore1.Exec(t, "RESTORE SYSTEM USERS FROM $1", localFoo+"/3")
 
-		sqlDBRestore1.CheckQueryResults(t, "SELECT username, \"hashedPassword\", \"isRole\" FROM system.users", [][]string{
-			{"admin", "", "true"},
-			{"app", "NULL", "false"},
-			{"app_role", "NULL", "true"},
-			{"root", "", "false"},
-			{"test", "NULL", "false"},
-			{"test_role", "NULL", "true"},
+		sqlDBRestore1.CheckQueryResults(t, "SELECT username, \"hashedPassword\", \"isRole\", \"user_id\" FROM system.users", [][]string{
+			{"admin", "", "true", "2"},
+			{"app", "NULL", "false", "102"},
+			{"app_role", "NULL", "true", "103"},
+			{"root", "", "false", "1"},
+			{"test", "NULL", "false", "104"},
+			{"test_role", "NULL", "true", "105"},
+			{"testuser", "NULL", "false", "101"},
 		})
 		sqlDBRestore1.CheckQueryResults(t, "SELECT \"role\", \"member\", \"isAdmin\" FROM system.role_members", [][]string{
 			{"admin", "root", "true"},
@@ -9475,6 +9478,7 @@ func TestBackupRestoreSystemUsers(t *testing.T) {
 			{"root", "", "{admin}"},
 			{"test", "", "{}"},
 			{"test_role", "", "{}"},
+			{"testuser", "", "{}"},
 		})
 	})
 }

pkg/ccl/backupccl/restore_planning.go

@@ -226,6 +226,11 @@ func allocateDescriptorRewrites(
 			}
 			for _, seqID := range col.UsesSequenceIds {
 				if _, ok := tablesByID[seqID]; !ok {
+					if seqID == keys.RoleIDSequenceID {
+						// We don't have to restore the RoleIDSequence, the sequence should
+						// already exist in the system database.
+						continue
+					}
 					if !opts.SkipMissingSequences {
 						return nil, errors.Errorf(
 							"cannot restore table %q without referenced sequence %d (or %q option)",