kv,migration: rm code handling legacy raft truncated state

Fixes #66544. We fully migrated away from the replicated truncated state
and the old range applied state keys (RaftAppliedIndexLegacyKey,
LeaseAppliedIndexLegacyKey, and RangeStatsLegacyKey) in #58088. We're
now guaranteed to never see the legacy truncated+applied state
representations, making this code (finally) safe to delete.

Release justification: cluster version cleanup
Release note: None

---

This turned out to be pretty hairy and invasive. I'll wait for a few CI
runs and inspect the diffs here a bit more closely. Given the surface
area here, I'm curious if we feel this is worth getting in during
stability. Some questions to consider:

- The various legacy keys that were removed were removed in their
  entirety. Our CLI to scan over store keys will no longer recognize these
  keys. Is that ok?
- I don't think we need any checks to make sure we're not re-using some
  of these keys in the future -- but I'd like other opinions.
- Looks like we re-purposed the LocalRaftTruncatedStateLegacySuffix for
  the unreplicated truncated key as well, so just renamed it more
  appropriately.
- v21.1 nodes have to interop with v20.2 nodes where the legacy
  representation was possible, and it identified such cases through
  booleans in proto messages (SnapshotRequest.Header.UseUnreplicatedTruncatedState
  for example). This means that we still need to explicitly set them in
  v21.2 code. Crucially we'll stop reading these fields in v21.2 code,
  letting us remove these fields entirely in v22.1.
- The treatment above does not extend to ReplicaState.UsingAppliedStateKey;
  that field was only being used to trigger an idempotent migration to
  start using the newer applied state key representation, not as a way
  to express that the replica should expect the legacy representation.
  Since #58088 has already migrated every range in the system, we no
  longer need to trigger anything, and this field can be removed.

pkg/cli/debug_check_store.go

@@ -252,7 +252,7 @@ func checkStoreRaftState(
 					return err
 				}
 				getReplicaInfo(rangeID).committedIndex = hs.Commit
-			case bytes.Equal(suffix, keys.LocalRaftTruncatedStateLegacySuffix):
+			case bytes.Equal(suffix, keys.LocalRaftTruncatedStateSuffix):
 				var trunc roachpb.RaftTruncatedState
 				if err := kv.Value.GetProto(&trunc); err != nil {
 					return err
@@ -264,12 +264,6 @@ func checkStoreRaftState(
 					return err
 				}
 				getReplicaInfo(rangeID).appliedIndex = state.RaftAppliedIndex
-			case bytes.Equal(suffix, keys.LocalRaftAppliedIndexLegacySuffix):
-				idx, err := kv.Value.GetInt()
-				if err != nil {
-					return err
-				}
-				getReplicaInfo(rangeID).appliedIndex = uint64(idx)
 			case bytes.Equal(suffix, keys.LocalRaftLogSuffix):
 				_, index, err := encoding.DecodeUint64Ascending(detail)
 				if err != nil {

pkg/clusterversion/cockroach_versions.go

@@ -180,32 +180,6 @@ const (
 	//
 	// Start21_1 demarcates work towards CockroachDB v21.1.
 	Start21_1
-	// replacedTruncatedAndRangeAppliedStateMigration stands in for
-	// TruncatedAndRangeAppliedStateMigration which was	re-introduced after the
-	// migration job was introduced. This is necessary because the jobs
-	// infrastructure used to run this migration in v21.1 and its later alphas
-	// was introduced after this version was first introduced. Later code in the
-	// release relies on the job to run the migration but the job relies on
-	// its startup migrations having been run. Versions associated with long
-	// running migrations must follow deletedLongRunningMigrations.
-	replacedTruncatedAndRangeAppliedStateMigration
-	// replacedPostTruncatedAndRangeAppliedStateMigration is like the above
-	// version. See its comment.
-	replacedPostTruncatedAndRangeAppliedStateMigration
-	// TruncatedAndRangeAppliedStateMigration is part of the migration to stop
-	// using the legacy truncated state within KV. After the migration, we'll be
-	// using the unreplicated truncated state and the RangeAppliedState on all
-	// ranges. Callers that wish to assert on there no longer being any legacy
-	// will be able to do so after PostTruncatedAndRangeAppliedStateMigration is
-	// active. This lets remove any holdover code handling the possibility of
-	// replicated truncated state in 21.2.
-	//
-	// TODO(irfansharif): Do the above in 21.2.
-	TruncatedAndRangeAppliedStateMigration
-	// PostTruncatedAndRangeAppliedStateMigration is used to purge all replicas
-	// using the replicated legacy TruncatedState. It's also used in asserting
-	// that no replicated truncated state representation is found.
-	PostTruncatedAndRangeAppliedStateMigration
 	// TracingVerbosityIndependentSemantics marks a change in which trace spans
 	// are propagated across RPC boundaries independently of their verbosity setting.
 	// This requires a version gate this violates implicit assumptions in v20.2.
@@ -349,22 +323,6 @@ var versionsSingleton = keyedVersions{
 		Key:     Start21_1,
 		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 2},
 	},
-	{
-		Key:     replacedTruncatedAndRangeAppliedStateMigration,
-		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 14},
-	},
-	{
-		Key:     replacedPostTruncatedAndRangeAppliedStateMigration,
-		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 16},
-	},
-	{
-		Key:     TruncatedAndRangeAppliedStateMigration,
-		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 22},
-	},
-	{
-		Key:     PostTruncatedAndRangeAppliedStateMigration,
-		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 24},
-	},
 	{
 		Key:     TracingVerbosityIndependentSemantics,
 		Version: roachpb.Version{Major: 20, Minor: 2, Internal: 28},

pkg/keys/constants.go

@@ -80,17 +80,12 @@ var (
 	// LocalRangeAppliedStateSuffix is the suffix for the range applied state
 	// key.
 	LocalRangeAppliedStateSuffix = []byte("rask")
-	// LocalRaftAppliedIndexLegacySuffix is the suffix for the raft applied index.
-	LocalRaftAppliedIndexLegacySuffix = []byte("rfta")
-	// LocalRaftTruncatedStateLegacySuffix is the suffix for the legacy
-	// RaftTruncatedState. See VersionUnreplicatedRaftTruncatedState.
+	// LocalRaftTruncatedStateSuffix is the suffix for the
+	// RaftTruncatedState.
 	// Note: This suffix is also used for unreplicated Range-ID keys.
-	LocalRaftTruncatedStateLegacySuffix = []byte("rftt")
+	LocalRaftTruncatedStateSuffix = []byte("rftt")
 	// LocalRangeLeaseSuffix is the suffix for a range lease.
 	LocalRangeLeaseSuffix = []byte("rll-")
-	// LocalLeaseAppliedIndexLegacySuffix is the suffix for the applied lease
-	// index.
-	LocalLeaseAppliedIndexLegacySuffix = []byte("rlla")
 	// LocalRangePriorReadSummarySuffix is the suffix for a range's prior read
 	// summary.
 	LocalRangePriorReadSummarySuffix = []byte("rprs")

pkg/keys/doc.go

@@ -185,16 +185,12 @@ var _ = [...]interface{}{
 	//   range as a whole. Though they are replicated, they are unaddressable.
 	//   Typical examples are MVCC stats and the abort span. They all share
 	//   `LocalRangeIDPrefix` and `LocalRangeIDReplicatedInfix`.
-	AbortSpanKey,                // "abc-"
-	RangeGCThresholdKey,         // "lgc-"
-	RangeAppliedStateKey,        // "rask"
-	RaftAppliedIndexLegacyKey,   // "rfta"
-	RaftTruncatedStateLegacyKey, // "rftt"
-	RangeLeaseKey,               // "rll-"
-	LeaseAppliedIndexLegacyKey,  // "rlla"
-	RangePriorReadSummaryKey,    // "rprs"
-	RangeVersionKey,             // "rver"
-	RangeStatsLegacyKey,         // "stat"
+	AbortSpanKey,             // "abc-"
+	RangeGCThresholdKey,      // "lgc-"
+	RangeAppliedStateKey,     // "rask"
+	RangeLeaseKey,            // "rll-"
+	RangePriorReadSummaryKey, // "rprs"
+	RangeVersionKey,          // "rver"
 
 	//   2. Unreplicated range-ID local keys: These contain metadata that
 	//   pertain to just one replica of a range. They are unreplicated and

pkg/keys/keys.go

@@ -239,33 +239,11 @@ func DecodeAbortSpanKey(key roachpb.Key, dest []byte) (uuid.UUID, error) {
 
 // RangeAppliedStateKey returns a system-local key for the range applied state key.
 // This key has subsumed the responsibility of the following three keys:
-// - RaftAppliedIndexLegacyKey
-// - LeaseAppliedIndexLegacyKey
 // - RangeStatsLegacyKey
 func RangeAppliedStateKey(rangeID roachpb.RangeID) roachpb.Key {
 	return MakeRangeIDPrefixBuf(rangeID).RangeAppliedStateKey()
 }
 
-// RaftAppliedIndexLegacyKey returns a system-local key for a raft applied index.
-// The key is no longer written to. Its responsibility has been subsumed by the
-// RangeAppliedStateKey.
-func RaftAppliedIndexLegacyKey(rangeID roachpb.RangeID) roachpb.Key {
-	return MakeRangeIDPrefixBuf(rangeID).RaftAppliedIndexLegacyKey()
-}
-
-// LeaseAppliedIndexLegacyKey returns a system-local key for a lease applied index.
-// The key is no longer written to. Its responsibility has been subsumed by the
-// RangeAppliedStateKey.
-func LeaseAppliedIndexLegacyKey(rangeID roachpb.RangeID) roachpb.Key {
-	return MakeRangeIDPrefixBuf(rangeID).LeaseAppliedIndexLegacyKey()
-}
-
-// RaftTruncatedStateLegacyKey returns a system-local key for a RaftTruncatedState.
-// See VersionUnreplicatedRaftTruncatedState.
-func RaftTruncatedStateLegacyKey(rangeID roachpb.RangeID) roachpb.Key {
-	return MakeRangeIDPrefixBuf(rangeID).RaftTruncatedStateLegacyKey()
-}
-
 // RangeLeaseKey returns a system-local key for a range lease.
 func RangeLeaseKey(rangeID roachpb.RangeID) roachpb.Key {
 	return MakeRangeIDPrefixBuf(rangeID).RangeLeaseKey()
@@ -277,13 +255,6 @@ func RangePriorReadSummaryKey(rangeID roachpb.RangeID) roachpb.Key {
 	return MakeRangeIDPrefixBuf(rangeID).RangePriorReadSummaryKey()
 }
 
-// RangeStatsLegacyKey returns the key for accessing the MVCCStats struct for
-// the specified Range ID. The key is no longer written to. Its responsibility
-// has been subsumed by the RangeAppliedStateKey.
-func RangeStatsLegacyKey(rangeID roachpb.RangeID) roachpb.Key {
-	return MakeRangeIDPrefixBuf(rangeID).RangeStatsLegacyKey()
-}
-
 // RangeGCThresholdKey returns a system-local key for last used GC threshold on the
 // user keyspace. Reads and writes <= this timestamp will not be served.
 func RangeGCThresholdKey(rangeID roachpb.RangeID) roachpb.Key {
@@ -951,23 +922,6 @@ func (b RangeIDPrefixBuf) RangeAppliedStateKey() roachpb.Key {
 	return append(b.replicatedPrefix(), LocalRangeAppliedStateSuffix...)
 }
 
-// RaftAppliedIndexLegacyKey returns a system-local key for a raft applied index.
-// See comment on RaftAppliedIndexLegacyKey function.
-func (b RangeIDPrefixBuf) RaftAppliedIndexLegacyKey() roachpb.Key {
-	return append(b.replicatedPrefix(), LocalRaftAppliedIndexLegacySuffix...)
-}
-
-// LeaseAppliedIndexLegacyKey returns a system-local key for a lease applied index.
-// See comment on LeaseAppliedIndexLegacyKey function.
-func (b RangeIDPrefixBuf) LeaseAppliedIndexLegacyKey() roachpb.Key {
-	return append(b.replicatedPrefix(), LocalLeaseAppliedIndexLegacySuffix...)
-}
-
-// RaftTruncatedStateLegacyKey returns a system-local key for a RaftTruncatedState.
-func (b RangeIDPrefixBuf) RaftTruncatedStateLegacyKey() roachpb.Key {
-	return append(b.replicatedPrefix(), LocalRaftTruncatedStateLegacySuffix...)
-}
-
 // RangeLeaseKey returns a system-local key for a range lease.
 func (b RangeIDPrefixBuf) RangeLeaseKey() roachpb.Key {
 	return append(b.replicatedPrefix(), LocalRangeLeaseSuffix...)
@@ -979,13 +933,6 @@ func (b RangeIDPrefixBuf) RangePriorReadSummaryKey() roachpb.Key {
 	return append(b.replicatedPrefix(), LocalRangePriorReadSummarySuffix...)
 }
 
-// RangeStatsLegacyKey returns the key for accessing the MVCCStats struct
-// for the specified Range ID.
-// See comment on RangeStatsLegacyKey function.
-func (b RangeIDPrefixBuf) RangeStatsLegacyKey() roachpb.Key {
-	return append(b.replicatedPrefix(), LocalRangeStatsLegacySuffix...)
-}
-
 // RangeGCThresholdKey returns a system-local key for the GC threshold.
 func (b RangeIDPrefixBuf) RangeGCThresholdKey() roachpb.Key {
 	return append(b.replicatedPrefix(), LocalRangeGCThresholdSuffix...)
@@ -1003,7 +950,7 @@ func (b RangeIDPrefixBuf) RangeTombstoneKey() roachpb.Key {
 
 // RaftTruncatedStateKey returns a system-local key for a RaftTruncatedState.
 func (b RangeIDPrefixBuf) RaftTruncatedStateKey() roachpb.Key {
-	return append(b.unreplicatedPrefix(), LocalRaftTruncatedStateLegacySuffix...)
+	return append(b.unreplicatedPrefix(), LocalRaftTruncatedStateSuffix...)
 }
 
 // RaftHardStateKey returns a system-local key for a Raft HardState.

pkg/keys/keys_test.go

@@ -156,10 +156,7 @@ func TestKeyAddressError(t *testing.T) {
 		"local range ID key .* is not addressable": {
 			AbortSpanKey(0, uuid.MakeV4()),
 			RangeTombstoneKey(0),
-			RaftAppliedIndexLegacyKey(0),
-			RaftTruncatedStateLegacyKey(0),
 			RangeLeaseKey(0),
-			RangeStatsLegacyKey(0),
 			RaftHardStateKey(0),
 			RaftLogPrefix(0),
 			RaftLogKey(0, 0),

pkg/keys/printer.go

@@ -160,13 +160,11 @@ var (
 		{name: "RangeTombstone", suffix: LocalRangeTombstoneSuffix},
 		{name: "RaftHardState", suffix: LocalRaftHardStateSuffix},
 		{name: "RangeAppliedState", suffix: LocalRangeAppliedStateSuffix},
-		{name: "RaftAppliedIndex", suffix: LocalRaftAppliedIndexLegacySuffix},
-		{name: "LeaseAppliedIndex", suffix: LocalLeaseAppliedIndexLegacySuffix},
 		{name: "RaftLog", suffix: LocalRaftLogSuffix,
 			ppFunc: raftLogKeyPrint,
 			psFunc: raftLogKeyParse,
 		},
-		{name: "RaftTruncatedState", suffix: LocalRaftTruncatedStateLegacySuffix},
+		{name: "RaftTruncatedState", suffix: LocalRaftTruncatedStateSuffix},
 		{name: "RangeLastReplicaGCTimestamp", suffix: LocalRangeLastReplicaGCTimestampSuffix},
 		{name: "RangeLease", suffix: LocalRangeLeaseSuffix},
 		{name: "RangePriorReadSummary", suffix: LocalRangePriorReadSummarySuffix},

pkg/keys/printer_test.go

@@ -69,13 +69,9 @@ func TestPrettyPrint(t *testing.T) {
 
 		{keys.AbortSpanKey(roachpb.RangeID(1000001), txnID), fmt.Sprintf(`/Local/RangeID/1000001/r/AbortSpan/%q`, txnID), revertSupportUnknown},
 		{keys.RangeAppliedStateKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangeAppliedState", revertSupportUnknown},
-		{keys.RaftAppliedIndexLegacyKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RaftAppliedIndex", revertSupportUnknown},
-		{keys.LeaseAppliedIndexLegacyKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/LeaseAppliedIndex", revertSupportUnknown},
-		{keys.RaftTruncatedStateLegacyKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RaftTruncatedState", revertSupportUnknown},
 		{keys.RaftTruncatedStateKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/u/RaftTruncatedState", revertSupportUnknown},
 		{keys.RangeLeaseKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangeLease", revertSupportUnknown},
 		{keys.RangePriorReadSummaryKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangePriorReadSummary", revertSupportUnknown},
-		{keys.RangeStatsLegacyKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangeStats", revertSupportUnknown},
 		{keys.RangeGCThresholdKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangeGCThreshold", revertSupportUnknown},
 		{keys.RangeVersionKey(roachpb.RangeID(1000001)), "/Local/RangeID/1000001/r/RangeVersion", revertSupportUnknown},
 

pkg/kv/kvserver/batcheval/cmd_end_transaction.go

@@ -983,34 +983,6 @@ func splitTriggerHelper(
 			log.VEventf(ctx, 1, "LHS's GCThreshold of split is not set")
 		}
 
-		// We're about to write the initial state for the replica. We migrated
-		// the formerly replicated truncated state into unreplicated keyspace
-		// in 19.1, but this range may still be using the replicated version
-		// and we need to make a decision about what to use for the RHS that
-		// is consistent across the followers: do for the RHS what the LHS
-		// does: if the LHS has the legacy key, initialize the RHS with a
-		// legacy key as well.
-		//
-		// See VersionUnreplicatedRaftTruncatedState.
-		truncStateType := stateloader.TruncatedStateUnreplicated
-		if found, err := storage.MVCCGetProto(
-			ctx,
-			batch,
-			keys.RaftTruncatedStateLegacyKey(rec.GetRangeID()),
-			hlc.Timestamp{},
-			nil,
-			storage.MVCCGetOptions{},
-		); err != nil {
-			return enginepb.MVCCStats{}, result.Result{}, errors.Wrap(err, "unable to load legacy truncated state")
-		} else if found {
-			truncStateType = stateloader.TruncatedStateLegacyReplicated
-		}
-
-		replicaVersion, err := sl.LoadVersion(ctx, batch)
-		if err != nil {
-			return enginepb.MVCCStats{}, result.Result{}, errors.Wrap(err, "unable to load GCThreshold")
-		}
-
 		// Writing the initial state is subtle since this also seeds the Raft
 		// group. It becomes more subtle due to proposer-evaluated Raft.
 		//
@@ -1040,10 +1012,13 @@ func splitTriggerHelper(
 		// HardState via a call to synthesizeRaftState. Here, we only call
 		// writeInitialReplicaState which essentially writes a ReplicaState
 		// only.
-
+		replicaVersion, err := sl.LoadVersion(ctx, batch)
+		if err != nil {
+			return enginepb.MVCCStats{}, result.Result{}, errors.Wrap(err, "unable to load replica version")
+		}
 		*h.AbsPostSplitRight(), err = stateloader.WriteInitialReplicaState(
 			ctx, batch, *h.AbsPostSplitRight(), split.RightDesc, rightLease,
-			*gcThreshold, truncStateType, replicaVersion,
+			*gcThreshold, replicaVersion,
 		)
 		if err != nil {
 			return enginepb.MVCCStats{}, result.Result{}, errors.Wrap(err, "unable to write initial Replica state")