sql: deprecate TableDescriptor.GCMutations

This appears unused. While the schema changer adds entries that the gc
job subsequently removes, the only other code that made use of this
field (outside of tests) was FindIndexByID. FindIndexByID appears to
use it to return a special error that no one looks for.

Release note: None

pkg/jobs/registry_test.go

@@ -93,38 +93,16 @@ func writeMutation(
 	}
 }
 
-func writeGCMutation(
-	t *testing.T,
-	kvDB *kv.DB,
-	tableDesc *tabledesc.Mutable,
-	m descpb.TableDescriptor_GCDescriptorMutation,
-) {
-	tableDesc.GCMutations = append(tableDesc.GCMutations, m)
-	tableDesc.Version++
-	if err := catalog.ValidateSelf(tableDesc); err != nil {
-		t.Fatal(err)
-	}
-	if err := kvDB.Put(
-		context.Background(),
-		catalogkeys.MakeDescMetadataKey(keys.SystemSQLCodec, tableDesc.GetID()),
-		tableDesc.DescriptorProto(),
-	); err != nil {
-		t.Fatal(err)
-	}
-}
-
 type mutationOptions struct {
 	// Set if the desc should have any mutations of any sort.
 	hasMutation bool
-	// Set if the mutation being inserted is a GCMutation.
-	hasGCMutation bool
 	// Set if the desc should have a job that is dropping it.
 	hasDropJob bool
 }
 
 func (m mutationOptions) string() string {
-	return fmt.Sprintf("hasMutation=%s_hasGCMutation=%s_hasDropJob=%s",
-		strconv.FormatBool(m.hasMutation), strconv.FormatBool(m.hasGCMutation),
+	return fmt.Sprintf("hasMutation=%s_hasDropJob=%s",
+		strconv.FormatBool(m.hasMutation),
 		strconv.FormatBool(m.hasDropJob))
 }
 
@@ -172,7 +150,7 @@ func TestRegistryGC(t *testing.T) {
 	writeJob := func(name string, created, finished time.Time, status Status, mutOptions mutationOptions) string {
 		tableName := constructTableName(name, mutOptions)
 		if _, err := sqlDB.Exec(fmt.Sprintf(`
-CREATE DATABASE IF NOT EXISTS t; 
+CREATE DATABASE IF NOT EXISTS t;
 CREATE TABLE t."%s" (k VARCHAR PRIMARY KEY DEFAULT 'default', v VARCHAR,i VARCHAR NOT NULL DEFAULT 'i');
 INSERT INTO t."%s" VALUES('a', 'foo');
 `, tableName, tableName)); err != nil {
@@ -187,10 +165,6 @@ INSERT INTO t."%s" VALUES('a', 'foo');
 			writeColumnMutation(t, kvDB, tableDesc, "i", descpb.DescriptorMutation{State: descpb.
 				DescriptorMutation_DELETE_AND_WRITE_ONLY, Direction: descpb.DescriptorMutation_DROP})
 		}
-		if mutOptions.hasGCMutation {
-			writeGCMutation(t, kvDB, tableDesc, descpb.TableDescriptor_GCDescriptorMutation{})
-		}
-
 		payload, err := protoutil.Marshal(&jobspb.Payload{
 			Description: name,
 			// register a mutation on the table so that jobs that reference
@@ -222,58 +196,54 @@ INSERT INTO t."%s" VALUES('a', 'foo');
 
 	// Test the descriptor when any of the following are set.
 	// 1. Mutations
-	// 2. GC Mutations
-	// 3. A drop job
+	// 2. A drop job
 	for _, hasMutation := range []bool{true, false} {
-		for _, hasGCMutation := range []bool{true, false} {
-			for _, hasDropJob := range []bool{true, false} {
-				if !hasMutation && !hasGCMutation && !hasDropJob {
-					continue
-				}
-				mutOptions := mutationOptions{
-					hasMutation:   hasMutation,
-					hasGCMutation: hasGCMutation,
-					hasDropJob:    hasDropJob,
-				}
-				oldRunningJob := writeJob("old_running", muchEarlier, time.Time{}, StatusRunning, mutOptions)
-				oldSucceededJob := writeJob("old_succeeded", muchEarlier, muchEarlier.Add(time.Minute), StatusSucceeded, mutOptions)
-				oldFailedJob := writeJob("old_failed", muchEarlier, muchEarlier.Add(time.Minute),
-					StatusFailed, mutOptions)
-				oldRevertFailedJob := writeJob("old_revert_failed", muchEarlier, muchEarlier.Add(time.Minute),
-					StatusRevertFailed, mutOptions)
-				oldCanceledJob := writeJob("old_canceled", muchEarlier, muchEarlier.Add(time.Minute),
-					StatusCanceled, mutOptions)
-				newRunningJob := writeJob("new_running", earlier, earlier.Add(time.Minute), StatusRunning,
-					mutOptions)
-				newSucceededJob := writeJob("new_succeeded", earlier, earlier.Add(time.Minute), StatusSucceeded, mutOptions)
-				newFailedJob := writeJob("new_failed", earlier, earlier.Add(time.Minute), StatusFailed, mutOptions)
-				newRevertFailedJob := writeJob("new_revert_failed", earlier, earlier.Add(time.Minute), StatusRevertFailed, mutOptions)
-				newCanceledJob := writeJob("new_canceled", earlier, earlier.Add(time.Minute),
-					StatusCanceled, mutOptions)
-
-				db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
-					{oldRunningJob}, {oldSucceededJob}, {oldFailedJob}, {oldRevertFailedJob}, {oldCanceledJob},
-					{newRunningJob}, {newSucceededJob}, {newFailedJob}, {newRevertFailedJob}, {newCanceledJob}})
-
-				if err := s.JobRegistry().(*Registry).cleanupOldJobs(ctx, earlier); err != nil {
-					t.Fatal(err)
-				}
-				db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
-					{oldRunningJob}, {oldRevertFailedJob}, {newRunningJob}, {newSucceededJob},
-					{newFailedJob}, {newRevertFailedJob}, {newCanceledJob}})
+		for _, hasDropJob := range []bool{true, false} {
+			if !hasMutation && !hasDropJob {
+				continue
+			}
+			mutOptions := mutationOptions{
+				hasMutation: hasMutation,
+				hasDropJob:  hasDropJob,
+			}
+			oldRunningJob := writeJob("old_running", muchEarlier, time.Time{}, StatusRunning, mutOptions)
+			oldSucceededJob := writeJob("old_succeeded", muchEarlier, muchEarlier.Add(time.Minute), StatusSucceeded, mutOptions)
+			oldFailedJob := writeJob("old_failed", muchEarlier, muchEarlier.Add(time.Minute),
+				StatusFailed, mutOptions)
+			oldRevertFailedJob := writeJob("old_revert_failed", muchEarlier, muchEarlier.Add(time.Minute),
+				StatusRevertFailed, mutOptions)
+			oldCanceledJob := writeJob("old_canceled", muchEarlier, muchEarlier.Add(time.Minute),
+				StatusCanceled, mutOptions)
+			newRunningJob := writeJob("new_running", earlier, earlier.Add(time.Minute), StatusRunning,
+				mutOptions)
+			newSucceededJob := writeJob("new_succeeded", earlier, earlier.Add(time.Minute), StatusSucceeded, mutOptions)
+			newFailedJob := writeJob("new_failed", earlier, earlier.Add(time.Minute), StatusFailed, mutOptions)
+			newRevertFailedJob := writeJob("new_revert_failed", earlier, earlier.Add(time.Minute), StatusRevertFailed, mutOptions)
+			newCanceledJob := writeJob("new_canceled", earlier, earlier.Add(time.Minute),
+				StatusCanceled, mutOptions)
+
+			db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
+				{oldRunningJob}, {oldSucceededJob}, {oldFailedJob}, {oldRevertFailedJob}, {oldCanceledJob},
+				{newRunningJob}, {newSucceededJob}, {newFailedJob}, {newRevertFailedJob}, {newCanceledJob}})
+
+			if err := s.JobRegistry().(*Registry).cleanupOldJobs(ctx, earlier); err != nil {
+				t.Fatal(err)
+			}
+			db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
+				{oldRunningJob}, {oldRevertFailedJob}, {newRunningJob}, {newSucceededJob},
+				{newFailedJob}, {newRevertFailedJob}, {newCanceledJob}})
 
-				if err := s.JobRegistry().(*Registry).cleanupOldJobs(ctx, ts.Add(time.Minute*-10)); err != nil {
-					t.Fatal(err)
-				}
-				db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
-					{oldRunningJob}, {oldRevertFailedJob}, {newRunningJob}, {newRevertFailedJob}})
-
-				// Delete the revert failed, and running jobs for the next run of the
-				// test.
-				_, err := sqlDB.Exec(`DELETE FROM system.jobs WHERE id = $1 OR id = $2 OR id = $3 OR id = $4`,
-					oldRevertFailedJob, newRevertFailedJob, oldRunningJob, newRunningJob)
-				require.NoError(t, err)
+			if err := s.JobRegistry().(*Registry).cleanupOldJobs(ctx, ts.Add(time.Minute*-10)); err != nil {
+				t.Fatal(err)
 			}
+			db.CheckQueryResults(t, `SELECT id FROM system.jobs ORDER BY id`, [][]string{
+				{oldRunningJob}, {oldRevertFailedJob}, {newRunningJob}, {newRevertFailedJob}})
+
+			// Delete the revert failed, and running jobs for the next run of the
+			// test.
+			_, err := sqlDB.Exec(`DELETE FROM system.jobs WHERE id = $1 OR id = $2 OR id = $3 OR id = $4`,
+				oldRevertFailedJob, newRevertFailedJob, oldRunningJob, newRunningJob)
+			require.NoError(t, err)
 		}
 	}
 }

pkg/sql/catalog/descpb/structured.proto

@@ -1108,15 +1108,20 @@ message TableDescriptor {
                               (gogoproto.customname) = "JobID", deprecated = true];
   }
 
+  // Before 22.1:
   // The schema elements that have been dropped and whose underlying
   // data needs to be gc-ed. These schema elements have already transitioned
   // through the drop state machine when they were in the above mutations
   // list, and can be safely deleted. The names for these schema elements
   // can be reused. This list is separate because mutations can
   // lie in this list for a long time (gc deadline) and should not block
   // the execution of other schema changes on the table.
+  //
+  // Since 22.1 this is field is deprecated and no longer maintained.
+  // The index GC job still removes mutations it finds in this list.
   repeated GCDescriptorMutation gc_mutations = 33 [(gogoproto.nullable) = false,
-                                                  (gogoproto.customname) = "GCMutations"];
+                                                   (gogoproto.customname) = "GCMutations",
+                                                   deprecated = true];
 
   optional string create_query = 34 [(gogoproto.nullable) = false];
 

pkg/sql/catalog/descriptor.go

@@ -533,8 +533,6 @@ type TableDescriptor interface {
 	MakePublic() TableDescriptor
 	// AllMutations returns all of the table descriptor's mutations.
 	AllMutations() []Mutation
-	// GetGCMutations returns the table descriptor's GC mutations.
-	GetGCMutations() []descpb.TableDescriptor_GCDescriptorMutation
 	// GetMutationJobs returns the table descriptor's mutation jobs.
 	GetMutationJobs() []descpb.TableDescriptor_MutationJob
 

pkg/sql/catalog/lease/lease_test.go

@@ -1118,14 +1118,9 @@ INSERT INTO t.kv VALUES ('a', 'b');
 	}
 
 	testutils.SucceedsSoon(t, func() error {
-		if tableDesc := catalogkv.TestingGetTableDescriptor(kvDB, keys.SystemSQLCodec, "t", "kv"); len(tableDesc.GetGCMutations()) != 0 {
-			return errors.Errorf("%d gc mutations remaining", len(tableDesc.GetGCMutations()))
-		}
-		return nil
+		return tests.CheckKeyCountE(t, kvDB, tableSpan, 2)
 	})
 
-	tests.CheckKeyCount(t, kvDB, tableSpan, 2)
-
 	// TODO(erik, vivek): Transactions using old descriptors should fail and
 	// rollback when the index keys have been removed by ClearRange
 	// and the consistency issue is resolved. See #31563.

pkg/sql/catalog/tabledesc/structured.go

@@ -63,11 +63,6 @@ var ErrMissingColumns = errors.New("table must contain at least 1 column")
 // ErrMissingPrimaryKey indicates a table with no primary key.
 var ErrMissingPrimaryKey = errors.New("table must contain a primary key")
 
-// ErrIndexGCMutationsList is returned by FindIndexWithID to signal that the
-// index with the given ID does not have a descriptor and is in the garbage
-// collected mutations list.
-var ErrIndexGCMutationsList = errors.New("index in GC mutations list")
-
 // PostDeserializationTableDescriptorChanges are a set of booleans to indicate
 // which types of upgrades or fixes occurred when filling in the descriptor
 // after deserialization.

pkg/sql/catalog/tabledesc/table_desc.go

@@ -334,11 +334,6 @@ func (desc *wrapper) FindIndexWithID(id descpb.IndexID) (catalog.Index, error) {
 	}); idx != nil {
 		return idx, nil
 	}
-	for _, m := range desc.GCMutations {
-		if m.IndexID == id {
-			return nil, ErrIndexGCMutationsList
-		}
-	}
 	return nil, errors.Errorf("index-id \"%d\" does not exist", id)
 }
 

pkg/sql/gcjob/descriptor_utils.go

@@ -23,34 +23,42 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 )
 
+// updateDescriptorGCMutations removes the GCMutation for tie given
+// index ID. We no longer populate thif field, but we still search it
+// to remove existing entries.
 func updateDescriptorGCMutations(
 	ctx context.Context,
 	execCfg *sql.ExecutorConfig,
 	tableID descpb.ID,
 	garbageCollectedIndexID descpb.IndexID,
 ) error {
-	log.Infof(ctx, "updating GCMutations for table %d after removing index %d",
-		tableID, garbageCollectedIndexID)
-	// Remove the mutation from the table descriptor.
 	return sql.DescsTxn(ctx, execCfg, func(
 		ctx context.Context, txn *kv.Txn, descsCol *descs.Collection,
 	) error {
 		tbl, err := descsCol.GetMutableTableVersionByID(ctx, tableID, txn)
 		if err != nil {
 			return err
 		}
+		found := false
 		for i := 0; i < len(tbl.GCMutations); i++ {
 			other := tbl.GCMutations[i]
 			if other.IndexID == garbageCollectedIndexID {
 				tbl.GCMutations = append(tbl.GCMutations[:i], tbl.GCMutations[i+1:]...)
+				found = true
 				break
 			}
 		}
-		b := txn.NewBatch()
-		if err := descsCol.WriteDescToBatch(ctx, false /* kvTrace */, tbl, b); err != nil {
-			return err
+		if found {
+			log.Infof(ctx, "updating GCMutations for table %d after removing index %d",
+				tableID, garbageCollectedIndexID)
+			// Remove the mutation from the table descriptor.
+			b := txn.NewBatch()
+			if err := descsCol.WriteDescToBatch(ctx, false /* kvTrace */, tbl, b); err != nil {
+				return err
+			}
+			return txn.Run(ctx, b)
 		}
-		return txn.Run(ctx, b)
+		return nil
 	})
 }
 

pkg/sql/schema_changer.go

@@ -1090,15 +1090,6 @@ func (sc *SchemaChanger) done(ctx context.Context) error {
 			}
 			isRollback = m.IsRollback()
 			if idx := m.AsIndex(); m.Dropped() && idx != nil {
-				// how we keep track of dropped index names (for, e.g., zone config
-				// lookups), even though in the absence of a GC job there's nothing to
-				// clean them up.
-				scTable.GCMutations = append(
-					scTable.GCMutations,
-					descpb.TableDescriptor_GCDescriptorMutation{
-						IndexID: idx.GetID(),
-					})
-
 				description := sc.job.Payload().Description
 				if isRollback {
 					description = "ROLLBACK of " + description
@@ -1107,7 +1098,6 @@ func (sc *SchemaChanger) done(ctx context.Context) error {
 				if err := sc.createIndexGCJob(ctx, idx.GetID(), txn, description); err != nil {
 					return err
 				}
-
 			}
 			if constraint := m.AsConstraint(); constraint != nil && constraint.Adding() {
 				if constraint.IsForeignKey() && constraint.ForeignKey().Validity == descpb.ConstraintValidity_Unvalidated {