diff --git a/baseapp/abci.go b/baseapp/abci.go
index 273a35deb58..d29c7902263 100644
--- a/baseapp/abci.go
+++ b/baseapp/abci.go
@@ -44,7 +44,7 @@ func (app *BaseApp) InitChain(req abci.RequestInitChain) (res abci.ResponseInitC
 	if req.InitialHeight > 1 {
 		app.initialHeight = req.InitialHeight
 		initHeader = tmproto.Header{ChainID: req.ChainId, Height: req.InitialHeight, Time: req.Time}
-		err := app.store.SetInitialVersion(uint64(req.InitialHeight))
+		err := app.cms.SetInitialVersion(uint64(req.InitialHeight))
 		if err != nil {
 			panic(err)
 		}
@@ -114,7 +114,7 @@ func (app *BaseApp) InitChain(req abci.RequestInitChain) (res abci.ResponseInitC
 
 // Info implements the ABCI interface.
 func (app *BaseApp) Info(req abci.RequestInfo) abci.ResponseInfo {
-	lastCommitID := app.store.LastCommitID()
+	lastCommitID := app.cms.LastCommitID()
 
 	return abci.ResponseInfo{
 		Data:             app.name,
@@ -146,8 +146,8 @@ func (app *BaseApp) FilterPeerByID(info string) abci.ResponseQuery {
 // BeginBlock implements the ABCI application interface.
 func (app *BaseApp) BeginBlock(req abci.RequestBeginBlock) (res abci.ResponseBeginBlock) {
 
-	if app.store.TracingEnabled() {
-		app.store.SetTracingContext(sdk.TraceContext(
+	if app.cms.TracingEnabled() {
+		app.cms.SetTracingContext(sdk.TraceContext(
 			map[string]interface{}{"blockHeight": req.Header.Height},
 		))
 	}
@@ -313,9 +313,9 @@ func (app *BaseApp) Commit() (res abci.ResponseCommit) {
 
 	// Write the DeliverTx state into branched storage and commit the MultiStore.
 	// The write to the DeliverTx state writes all state transitions to the root
-	// MultiStore (app.store) so when Commit() is called it persists those values.
+	// MultiStore (app.cms) so when Commit() is called it persists those values.
 	app.deliverState.ms.Write()
-	commitID := app.store.Commit()
+	commitID := app.cms.Commit()
 	app.logger.Info("commit synced", "commit", fmt.Sprintf("%X", commitID))
 
 	// Reset the Check state to the latest committed.
@@ -624,7 +624,7 @@ func (app *BaseApp) createQueryContext(height int64, prove bool) (sdk.Context, e
 			)
 	}
 
-	version, err := app.store.GetVersion(height)
+	version, err := app.cms.GetVersion(height)
 	if err != nil {
 		return sdk.Context{},
 			sdkerrors.Wrapf(
@@ -778,12 +778,12 @@ func handleQueryApp(app *BaseApp, path []string, req abci.RequestQuery) abci.Res
 
 func handleQueryStore(app *BaseApp, path []string, req abci.RequestQuery) abci.ResponseQuery {
 	// "/store" prefix for store queries
-	queryable, ok := app.store.(sdk.Queryable)
+	queryable, ok := app.cms.(sdk.Queryable)
 	if !ok {
 		return sdkerrors.QueryResult(sdkerrors.Wrap(sdkerrors.ErrUnknownRequest, "multistore doesn't support queries"), app.trace)
 	}
 
-	req.Path = "/" + strings.Join(path[1:], "/") // = /store/main/key -> /main/key
+	req.Path = "/" + strings.Join(path[1:], "/")
 
 	if req.Height <= 1 && req.Prove {
 		return sdkerrors.QueryResult(
diff --git a/baseapp/baseapp.go b/baseapp/baseapp.go
index eef3eb6a530..d1077fe2ca7 100644
--- a/baseapp/baseapp.go
+++ b/baseapp/baseapp.go
@@ -67,7 +67,7 @@ type BaseApp struct { // nolint: maligned
 	name              string // application name from abci.Info
 	db                dbm.Connection
 	storeOpts         []StoreOption        // options to configure root store
-	store             sdk.CommitMultiStore // Main (uncached) state
+	cms               sdk.CommitMultiStore // Main (uncached) state
 	router            sdk.Router           // handle any kind of legacy message
 	queryRouter       sdk.QueryRouter      // router for redirecting query calls
 	grpcQueryRouter   *GRPCQueryRouter     // router for redirecting gRPC query calls
@@ -241,7 +241,7 @@ func (app *BaseApp) loadStore() error {
 			return err
 		}
 	}
-	app.store, err = multi.NewV1MultiStoreAsV2(app.db, config)
+	app.cms, err = multi.NewV1MultiStoreAsV2(app.db, config)
 	if err != nil {
 		return fmt.Errorf("failed to load store: %w", err)
 	}
@@ -257,17 +257,17 @@ func (app *BaseApp) SetMsgServiceRouter(msgServiceRouter *MsgServiceRouter) {
 }
 
 func (app *BaseApp) CloseStore() error {
-	return app.store.Close()
+	return app.cms.Close()
 }
 
 // LastCommitID returns the last CommitID of the multistore.
 func (app *BaseApp) LastCommitID() stypes.CommitID {
-	return app.store.LastCommitID()
+	return app.cms.LastCommitID()
 }
 
 // LastBlockHeight returns the last committed block height.
 func (app *BaseApp) LastBlockHeight() int64 {
-	return app.store.LastCommitID().Version
+	return app.cms.LastCommitID().Version
 }
 
 // Init initializes the app. It seals the app, preventing any
@@ -282,7 +282,7 @@ func (app *BaseApp) Init() error {
 	// needed for the export command which inits from store but never calls initchain
 	app.setCheckState(tmproto.Header{})
 	app.Seal()
-	return app.store.GetPruning().Validate()
+	return app.cms.GetPruning().Validate()
 }
 
 func (app *BaseApp) setMinGasPrices(gasPrices sdk.DecCoins) {
@@ -338,7 +338,7 @@ func (app *BaseApp) IsSealed() bool { return app.sealed }
 // provided header, and minimum gas prices set. It is set on InitChain and reset
 // on Commit.
 func (app *BaseApp) setCheckState(header tmproto.Header) {
-	ms := app.store.CacheWrap()
+	ms := app.cms.CacheWrap()
 	app.checkState = &state{
 		ms:  ms,
 		ctx: sdk.NewContext(ms, header, true, app.logger).WithMinGasPrices(app.minGasPrices),
@@ -350,7 +350,7 @@ func (app *BaseApp) setCheckState(header tmproto.Header) {
 // and provided header. It is set on InitChain and BeginBlock and set to nil on
 // Commit.
 func (app *BaseApp) setDeliverState(header tmproto.Header) {
-	ms := app.store.CacheWrap()
+	ms := app.cms.CacheWrap()
 	app.deliverState = &state{
 		ms:  ms,
 		ctx: sdk.NewContext(ms, header, false, app.logger),
diff --git a/baseapp/baseapp_test.go b/baseapp/baseapp_test.go
index c830ef3ac04..474e84e5046 100644
--- a/baseapp/baseapp_test.go
+++ b/baseapp/baseapp_test.go
@@ -21,7 +21,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	codectypes "github.com/cosmos/cosmos-sdk/codec/types"
 	dbm "github.com/cosmos/cosmos-sdk/db"
-	"github.com/cosmos/cosmos-sdk/db/memdb"
 	pruningtypes "github.com/cosmos/cosmos-sdk/pruning/types"
 	"github.com/cosmos/cosmos-sdk/snapshots"
 	snapshottypes "github.com/cosmos/cosmos-sdk/snapshots/types"
@@ -59,7 +58,7 @@ func defaultLogger() log.Logger {
 
 func newBaseApp(name string, options ...AppOption) *BaseApp {
 	logger := defaultLogger()
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	codec := codec.NewLegacyAmino()
 	registerTestCodec(codec)
 	return NewBaseApp(name, logger, db, testTxDecoder(codec), options...)
@@ -91,7 +90,7 @@ func setupBaseApp(t *testing.T, options ...AppOption) *BaseApp {
 	app := newBaseApp(t.Name(), options...)
 	require.Equal(t, t.Name(), app.Name())
 
-	app.SetParamStore(mock.NewParamStore(memdb.NewDB()))
+	app.SetParamStore(mock.NewParamStore(dbm.NewMemDB()))
 
 	// stores are mounted
 	err := app.Init()
@@ -106,13 +105,13 @@ func setupBaseAppWithSnapshots(t *testing.T, config *setupConfig) (*BaseApp, err
 	routerOpt := func(bapp *BaseApp) {
 		bapp.Router().AddRoute(sdk.NewRoute(routeMsgKeyValue, func(ctx sdk.Context, msg sdk.Msg) (*sdk.Result, error) {
 			kv := msg.(*msgKeyValue)
-			bapp.store.GetKVStore(capKey2).Set(kv.Key, kv.Value)
+			bapp.cms.GetKVStore(capKey2).Set(kv.Key, kv.Value)
 			return &sdk.Result{}, nil
 		}))
 	}
 
 	snapshotTimeout := 1 * time.Minute
-	snapshotStore, err := snapshots.NewStore(memdb.NewDB(), testutil.GetTempDir(t))
+	snapshotStore, err := snapshots.NewStore(dbm.NewMemDB(), testutil.GetTempDir(t))
 	require.NoError(t, err)
 
 	app := setupBaseApp(t,
@@ -168,9 +167,9 @@ func TestMountStores(t *testing.T) {
 	app := setupBaseApp(t)
 
 	// check both stores
-	store1 := app.store.GetKVStore(capKey1)
+	store1 := app.cms.GetKVStore(capKey1)
 	require.NotNil(t, store1)
-	store2 := app.store.GetKVStore(capKey2)
+	store2 := app.cms.GetKVStore(capKey2)
 	require.NotNil(t, store2)
 }
 
@@ -178,7 +177,7 @@ func TestMountStores(t *testing.T) {
 func TestLoadVersion(t *testing.T) {
 	logger := defaultLogger()
 	pruningOpt := SetPruning(pruningtypes.NewPruningOptions(pruningtypes.PruningNothing))
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	name := t.Name()
 	app := NewBaseApp(name, logger, db, nil, pruningOpt)
 
@@ -250,7 +249,7 @@ func checkStore(t *testing.T, db dbm.Connection, ver int64, storeKey string, k,
 func TestVersionSetterGetter(t *testing.T) {
 	logger := defaultLogger()
 	pruningOpt := SetPruning(pruningtypes.NewPruningOptions(pruningtypes.PruningDefault))
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	name := t.Name()
 	app := NewBaseApp(name, logger, db, nil, pruningOpt)
 	require.Equal(t, "", app.Version())
@@ -272,7 +271,7 @@ func TestLoadVersionPruning(t *testing.T) {
 	pruningOpt := SetPruning(pruningOptions)
 	capKey := sdk.NewKVStoreKey("key1")
 	schemaOpt := SetSubstores(capKey)
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	name := t.Name()
 	app := NewBaseApp(name, logger, db, nil, pruningOpt)
 
@@ -300,12 +299,14 @@ func TestLoadVersionPruning(t *testing.T) {
 	// TODO: behavior change -
 	// CacheMultiStoreWithVersion returned no error on missing version (?)
 	for _, v := range []int64{1, 2, 4} {
-		_, err = app.store.GetVersion(v)
+		s, err := app.cms.GetVersion(v)
+		require.NotNil(t, s)
 		require.NoError(t, err, "version=%v", v)
 	}
 
 	for _, v := range []int64{3, 5, 6, 7} {
-		_, err = app.store.GetVersion(v)
+		s, err := app.cms.GetVersion(v)
+		require.NotNil(t, s)
 		require.NoError(t, err, "version=%v", v)
 	}
 	require.NoError(t, app.CloseStore())
@@ -327,7 +328,7 @@ func testLoadVersionHelper(t *testing.T, app *BaseApp, expectedHeight int64, exp
 
 func TestOptionFunction(t *testing.T) {
 	logger := defaultLogger()
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	bap := NewBaseApp("starting name", logger, db, nil, testChangeNameHelper("new name"))
 	require.Equal(t, "new name", bap.Name(), "BaseApp should have had name changed via option function")
 }
@@ -416,7 +417,7 @@ func TestInitChainer(t *testing.T) {
 	name := t.Name()
 	// keep the db and logger ourselves so
 	// we can reload the same  app later
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	logger := defaultLogger()
 	capKey := sdk.NewKVStoreKey("main")
 	capKey2 := sdk.NewKVStoreKey("key2")
@@ -497,7 +498,7 @@ func TestInitChainer(t *testing.T) {
 
 func TestInitChain_WithInitialHeight(t *testing.T) {
 	name := t.Name()
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	logger := defaultLogger()
 	app := NewBaseApp(name, logger, db, nil)
 
@@ -513,7 +514,7 @@ func TestInitChain_WithInitialHeight(t *testing.T) {
 
 func TestBeginBlock_WithInitialHeight(t *testing.T) {
 	name := t.Name()
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	logger := defaultLogger()
 	app := NewBaseApp(name, logger, db, nil)
 
@@ -1963,7 +1964,7 @@ func TestWithRouter(t *testing.T) {
 }
 
 func TestBaseApp_EndBlock(t *testing.T) {
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	name := t.Name()
 	logger := defaultLogger()
 
@@ -1974,7 +1975,7 @@ func TestBaseApp_EndBlock(t *testing.T) {
 	}
 
 	app := NewBaseApp(name, logger, db, nil)
-	app.SetParamStore(mock.NewParamStore(memdb.NewDB()))
+	app.SetParamStore(mock.NewParamStore(dbm.NewMemDB()))
 	app.InitChain(abci.RequestInitChain{
 		ConsensusParams: cp,
 	})
@@ -1995,11 +1996,11 @@ func TestBaseApp_EndBlock(t *testing.T) {
 }
 
 func TestBaseApp_Init(t *testing.T) {
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	name := t.Name()
 	logger := defaultLogger()
 
-	snapshotStore, err := snapshots.NewStore(memdb.NewDB(), testutil.GetTempDir(t))
+	snapshotStore, err := snapshots.NewStore(dbm.NewMemDB(), testutil.GetTempDir(t))
 	require.NoError(t, err)
 
 	testCases := map[string]struct {
@@ -2140,7 +2141,7 @@ func TestBaseApp_Init(t *testing.T) {
 		}
 
 		// Check that settings were set correctly
-		actualPruning := tc.bapp.store.GetPruning()
+		actualPruning := tc.bapp.cms.GetPruning()
 		require.Equal(t, tc.expectedPruning, actualPruning)
 
 		if tc.expectedSnapshot.Interval == snapshottypes.SnapshotIntervalOff {
diff --git a/baseapp/options.go b/baseapp/options.go
index f6c3498fd97..bbbaf16ea5e 100644
--- a/baseapp/options.go
+++ b/baseapp/options.go
@@ -232,8 +232,8 @@ func (app *BaseApp) SetSnapshot(snapshotStore *snapshots.Store, opts snapshottyp
 		app.snapshotManager = nil
 		return
 	}
-	app.store.SetSnapshotInterval(opts.Interval)
-	app.snapshotManager = snapshots.NewManager(snapshotStore, opts, app.store, nil, app.logger)
+	app.cms.SetSnapshotInterval(opts.Interval)
+	app.snapshotManager = snapshots.NewManager(snapshotStore, opts, app.cms, nil, app.logger)
 }
 
 // SetInterfaceRegistry sets the InterfaceRegistry.
@@ -247,7 +247,7 @@ func (app *BaseApp) SetInterfaceRegistry(registry types.InterfaceRegistry) {
 func (app *BaseApp) SetStreamingService(s StreamingService) {
 	// add the listeners for each StoreKey
 	for key, lis := range s.Listeners() {
-		app.store.AddListeners(key, lis)
+		app.cms.AddListeners(key, lis)
 	}
 	// register the StreamingService within the BaseApp
 	// BaseApp will pass BeginBlock, DeliverTx, and EndBlock requests and responses to the streaming services to update their ABCI context
diff --git a/baseapp/test_helpers.go b/baseapp/test_helpers.go
index 08180075ce6..49081943a2b 100644
--- a/baseapp/test_helpers.go
+++ b/baseapp/test_helpers.go
@@ -47,12 +47,12 @@ func (app *BaseApp) NewContext(isCheckTx bool, header tmproto.Header) sdk.Contex
 }
 
 func (app *BaseApp) NewUncachedContext(isCheckTx bool, header tmproto.Header) sdk.Context {
-	return sdk.NewContext(app.store, header, isCheckTx, app.logger)
+	return sdk.NewContext(app.cms, header, isCheckTx, app.logger)
 }
 
 // NewContextAt creates a context using a (read-only) store at a given block height.
 func (app *BaseApp) NewContextAt(isCheckTx bool, header tmproto.Header, height int64) (sdk.Context, error) {
-	view, err := app.store.GetVersion(height)
+	view, err := app.cms.GetVersion(height)
 	if err != nil {
 		return sdk.Context{}, err
 	}
diff --git a/db/types/types.go b/db/types/types.go
index 8d024c175ea..39e48eab0ed 100644
--- a/db/types/types.go
+++ b/db/types/types.go
@@ -50,7 +50,6 @@ type Connection interface {
 	// SaveNextVersion saves the current contents of the database and returns the next version ID,
 	// which will be `Versions().Last()+1`.
 	// Returns an error if any open Writer transactions exist.
-	// TODO: rename to something more descriptive?
 	SaveNextVersion() (uint64, error)
 
 	// SaveVersion attempts to save database at a specific version ID, which must be greater than or
diff --git a/internal/db/tmdb_adapter.go b/internal/db/tmdb_adapter.go
index f5e1805f968..0bece64cf67 100644
--- a/internal/db/tmdb_adapter.go
+++ b/internal/db/tmdb_adapter.go
@@ -8,7 +8,7 @@ package db
 import (
 	"errors"
 
-	dbm "github.com/cosmos/cosmos-sdk/db"
+	dbm "github.com/cosmos/cosmos-sdk/db/types"
 
 	tmdb "github.com/tendermint/tm-db"
 )
diff --git a/server/export_test.go b/server/export_test.go
index 21c800de63c..133a1b16718 100644
--- a/server/export_test.go
+++ b/server/export_test.go
@@ -21,7 +21,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/client"
 	"github.com/cosmos/cosmos-sdk/client/flags"
 	dbm "github.com/cosmos/cosmos-sdk/db"
-	"github.com/cosmos/cosmos-sdk/db/memdb"
 	"github.com/cosmos/cosmos-sdk/server"
 	"github.com/cosmos/cosmos-sdk/server/types"
 	"github.com/cosmos/cosmos-sdk/simapp"
@@ -128,7 +127,7 @@ func setupApp(t *testing.T, tempDir string) (*simapp.SimApp, context.Context, *t
 	}
 
 	logger, _ := log.NewDefaultLogger("plain", "info", false)
-	db := memdb.NewDB()
+	db := dbm.NewMemDB()
 	encCfg := simapp.MakeTestEncodingConfig()
 	app := simapp.NewSimApp(logger, db, nil, encCfg, simtestutil.NewAppOptionsWithFlagHome(tempDir))
 
diff --git a/simapp/sim_test.go b/simapp/sim_test.go
index 879f65b3f7a..1d02fd7c109 100644
--- a/simapp/sim_test.go
+++ b/simapp/sim_test.go
@@ -353,7 +353,7 @@ func TestAppStateDeterminism(t *testing.T) {
 			require.NoError(t, err)
 
 			if config.Commit {
-				PrintStats(db) //TODO
+				PrintStats(db)
 			}
 
 			appHash := app.LastCommitID().Hash
diff --git a/simapp/simd/cmd/root.go b/simapp/simd/cmd/root.go
index aa1ed0624cd..a316f2b1a17 100644
--- a/simapp/simd/cmd/root.go
+++ b/simapp/simd/cmd/root.go
@@ -21,7 +21,6 @@ import (
 	"github.com/cosmos/cosmos-sdk/client/keys"
 	"github.com/cosmos/cosmos-sdk/client/rpc"
 	dbm "github.com/cosmos/cosmos-sdk/db"
-	"github.com/cosmos/cosmos-sdk/db/badgerdb"
 	"github.com/cosmos/cosmos-sdk/server"
 	serverconfig "github.com/cosmos/cosmos-sdk/server/config"
 	servertypes "github.com/cosmos/cosmos-sdk/server/types"
@@ -269,7 +268,7 @@ func (a appCreator) newApp(
 	}
 
 	snapshotDir := filepath.Join(cast.ToString(appOpts.Get(flags.FlagHome)), "data", "snapshots")
-	snapshotDB, err := badgerdb.NewDB(filepath.Join(snapshotDir, "metadata"))
+	snapshotDB, err := dbm.NewDB("metadata", dbm.BadgerDBBackend, snapshotDir)
 	if err != nil {
 		panic(err)
 	}
diff --git a/store/v2alpha1/multi/compat.go b/store/v2alpha1/multi/compat.go
index 7047e69b7c4..07f0088a7d5 100644
--- a/store/v2alpha1/multi/compat.go
+++ b/store/v2alpha1/multi/compat.go
@@ -104,8 +104,7 @@ func (st *compatStore) LoadVersionAndUpgrade(ver int64, upgrades *v1.StoreUpgrad
 }
 
 func (st *compatStore) LoadVersion(ver int64) error {
-	// TODO
-	// cache a viewStore representing "current" version?
+	// TODO: could cache a viewStore representing "current" version
 	panic("unsupported: LoadVersion")
 }
 
diff --git a/store/v2alpha1/multi/store.go b/store/v2alpha1/multi/store.go
index f14cfb29dd9..d69c5d2e46c 100644
--- a/store/v2alpha1/multi/store.go
+++ b/store/v2alpha1/multi/store.go
@@ -68,7 +68,7 @@ type StoreParams struct {
 	// Contains the store schema and methods to modify it
 	SchemaBuilder
 	storeKeys
-	// Inter-block persistent cache to use. TODO: not implemented
+	// Inter-block persistent cache to use. TODO: not used/impl'd
 	PersistentCache types.MultiStorePersistentCache
 	// Any pending upgrades to apply on loading.
 	Upgrades *types.StoreUpgrades
@@ -940,7 +940,7 @@ func (reg *SchemaBuilder) registerName(key string, typ types.StoreType) error {
 	if has {
 		return fmt.Errorf("name already exists: %v", key)
 	}
-	// TODO auth vs authz ?
+	// // Prefix conflict check: disabled; obviated by varint encoding
 	// if i > 0 && strings.HasPrefix(key, reg.reserved[i-1]) {
 	// 	return fmt.Errorf("name conflict: '%v' exists, cannot add '%v'", reg.reserved[i-1], key)
 	// }
diff --git a/store/v2alpha1/multi/store_test.go b/store/v2alpha1/multi/store_test.go
index 662d5872cac..51b2570a088 100644
--- a/store/v2alpha1/multi/store_test.go
+++ b/store/v2alpha1/multi/store_test.go
@@ -79,13 +79,14 @@ func TestStoreParams(t *testing.T) {
 	require.Error(t, opts.RegisterSubstore(skey_1, types.StoreTypeTransient))
 	require.NoError(t, opts.RegisterSubstore(skey_mem1, types.StoreTypeMemory))
 	require.NoError(t, opts.RegisterSubstore(skey_tran1, types.StoreTypeTransient))
-	// Ensure that no prefix conflicts are allowed
+	// Unambiguous prefixes are valid
 	require.NoError(t, opts.RegisterSubstore(skey_1, types.StoreTypePersistent))
 	require.NoError(t, opts.RegisterSubstore(skey_2, types.StoreTypePersistent))
 	require.NoError(t, opts.RegisterSubstore(skey_3b, types.StoreTypePersistent))
-	require.Error(t, opts.RegisterSubstore(skey_1b, types.StoreTypePersistent))
-	require.Error(t, opts.RegisterSubstore(skey_2b, types.StoreTypePersistent))
-	require.Error(t, opts.RegisterSubstore(skey_3, types.StoreTypePersistent))
+	// Prefix conflicts are allowed
+	// require.Error(t, opts.RegisterSubstore(skey_1b, types.StoreTypePersistent))
+	// require.Error(t, opts.RegisterSubstore(skey_2b, types.StoreTypePersistent))
+	// require.Error(t, opts.RegisterSubstore(skey_3, types.StoreTypePersistent))
 }
 
 func TestMultiStoreBasic(t *testing.T) {
diff --git a/store/v2alpha1/types.go b/store/v2alpha1/types.go
index c0a67bb762e..fed95acb088 100644
--- a/store/v2alpha1/types.go
+++ b/store/v2alpha1/types.go
@@ -104,5 +104,5 @@ type CacheMultiStore interface {
 }
 
 // MultiStorePersistentCache provides inter-block (persistent) caching capabilities for a CommitMultiStore.
-// TODO: placeholder. Implement and redefine this
+// TODO: placeholder, not implemented yet, nor used in store
 type MultiStorePersistentCache = v1.MultiStorePersistentCache
diff --git a/x/upgrade/types/storeloader_test.go b/x/upgrade/types/storeloader_test.go
index a54d20b5f58..2b6d7d6b923 100644
--- a/x/upgrade/types/storeloader_test.go
+++ b/x/upgrade/types/storeloader_test.go
@@ -14,7 +14,6 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/baseapp"
 	dbm "github.com/cosmos/cosmos-sdk/db"
-	"github.com/cosmos/cosmos-sdk/db/memdb"
 	pruningtypes "github.com/cosmos/cosmos-sdk/pruning/types"
 	"github.com/cosmos/cosmos-sdk/server"
 	storetypes "github.com/cosmos/cosmos-sdk/store/types"
@@ -119,7 +118,7 @@ func TestSetLoader(t *testing.T) {
 			require.NoError(t, loadConfig.RegisterSubstore(tc.loadStoreKey, storetypes.StoreTypePersistent))
 
 			// prepare a db with some data
-			db := memdb.NewDB()
+			db := dbm.NewMemDB()
 			initStore(t, db, origConfig, tc.origStoreKey, k, v)
 
 			// load the app with the existing db