Merge PR #7415: Return empty store tree on non-existing version

CHANGELOG.md

@@ -217,6 +217,7 @@ invalid or incomplete requests.
 * (x/genutil) [\#5938](https://github.com/cosmos/cosmos-sdk/pull/5938) Fix `InitializeNodeValidatorFiles` error handling.
 * (x/staking) [\#5949](https://github.com/cosmos/cosmos-sdk/pull/5949) Skip staking `HistoricalInfoKey` in simulations as headers are not exported.
 * (client) [\#5964](https://github.com/cosmos/cosmos-sdk/issues/5964) `--trust-node` is now false by default - for real. Users must ensure it is set to true if they don't want to enable the verifier.
+* (kvstore) [\#7415](https://github.com/cosmos/cosmos-sdk/pull/7415) Allow new stores to be registered during on-chain upgrades.
 
 ### State Machine Breaking
 

baseapp/baseapp_test.go

@@ -422,7 +422,7 @@ func TestLoadVersionPruning(t *testing.T) {
 
 	for _, v := range []int64{1, 2, 4} {
 		_, err = app.cms.CacheMultiStoreWithVersion(v)
-		require.Error(t, err)
+		require.NoError(t, err)
 	}
 
 	for _, v := range []int64{3, 5, 6, 7} {

go.mod

@@ -4,6 +4,7 @@ module github.com/cosmos/cosmos-sdk
 
 require (
 	github.com/99designs/keyring v1.1.6
+	github.com/DataDog/zstd v1.4.5 // indirect
 	github.com/armon/go-metrics v0.3.4
 	github.com/bgentry/speakeasy v0.1.0
 	github.com/btcsuite/btcd v0.21.0-beta
@@ -12,11 +13,15 @@ require (
 	github.com/cosmos/go-bip39 v0.0.0-20180819234021-555e2067c45d
 	github.com/cosmos/iavl v0.15.0-rc3
 	github.com/cosmos/ledger-cosmos-go v0.11.1
+	github.com/dgraph-io/badger/v2 v2.2007.2 // indirect
+	github.com/dgraph-io/ristretto v0.0.3 // indirect
+	github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 // indirect
 	github.com/enigmampc/btcutil v1.0.3-0.20200723161021-e2fb6adb2a25
 	github.com/gogo/gateway v1.1.0
 	github.com/gogo/protobuf v1.3.1
 	github.com/golang/mock v1.4.4
 	github.com/golang/protobuf v1.4.2
+	github.com/golang/snappy v0.0.2 // indirect
 	github.com/gorilla/handlers v1.5.1
 	github.com/gorilla/mux v1.8.0
 	github.com/grpc-ecosystem/grpc-gateway v1.15.2
@@ -43,6 +48,8 @@ require (
 	github.com/tendermint/tendermint v0.34.0-rc4.0.20201005135527-d7d0ffea13c6
 	github.com/tendermint/tm-db v0.6.2
 	golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a
+	golang.org/x/net v0.0.0-20200930145003-4acb6c075d10 // indirect
+	golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f // indirect
 	google.golang.org/genproto v0.0.0-20200825200019-8632dd797987
 	google.golang.org/grpc v1.32.0
 	google.golang.org/protobuf v1.25.0

go.sum

@@ -26,6 +26,8 @@ github.com/ChainSafe/go-schnorrkel v0.0.0-20200405005733-88cbf1b4c40d/go.mod h1:
 github.com/DataDog/datadog-go v3.2.0+incompatible/go.mod h1:LButxg5PwREeZtORoXG3tL4fMGNddJ+vMq1mwgfaqoQ=
 github.com/DataDog/zstd v1.4.1 h1:3oxKN3wbHibqx897utPC2LTQU4J+IHWWJO+glkAkpFM=
 github.com/DataDog/zstd v1.4.1/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
+github.com/DataDog/zstd v1.4.5 h1:EndNeuB0l9syBZhut0wns3gV1hL8zX8LIu6ZiVHWLIQ=
+github.com/DataDog/zstd v1.4.5/go.mod h1:1jcaCB/ufaK+sKp1NBhlGmpz41jOoPQ35bpF36t7BBo=
 github.com/Knetic/govaluate v3.0.1-0.20171022003610-9aa49832a739+incompatible/go.mod h1:r7JcOSlj0wfOMncg0iLm8Leh48TZaKVeNIfJntJ2wa0=
 github.com/OneOfOne/xxhash v1.2.2 h1:KMrpdQIwFcEqXDklaen+P1axHaj9BSKzvpUUfnHldSE=
 github.com/OneOfOne/xxhash v1.2.2/go.mod h1:HSdplMjZKSmBqAxg5vPj2TmRDmfkzw+cTzAElWljhcU=
@@ -139,13 +141,19 @@ github.com/dgraph-io/badger/v2 v2.0.3 h1:inzdf6VF/NZ+tJ8RwwYMjJMvsOALTHYdozn0qSl
 github.com/dgraph-io/badger/v2 v2.0.3/go.mod h1:3KY8+bsP8wI0OEnQJAKpd4wIJW/Mm32yw2j/9FUVnIM=
 github.com/dgraph-io/badger/v2 v2.2007.1 h1:t36VcBCpo4SsmAD5M8wVv1ieVzcALyGfaJ92z4ccULM=
 github.com/dgraph-io/badger/v2 v2.2007.1/go.mod h1:26P/7fbL4kUZVEVKLAKXkBXKOydDmM2p1e+NhhnBCAE=
+github.com/dgraph-io/badger/v2 v2.2007.2 h1:EjjK0KqwaFMlPin1ajhP943VPENHJdEz1KLIegjaI3k=
+github.com/dgraph-io/badger/v2 v2.2007.2/go.mod h1:26P/7fbL4kUZVEVKLAKXkBXKOydDmM2p1e+NhhnBCAE=
 github.com/dgraph-io/ristretto v0.0.2-0.20200115201040-8f368f2f2ab3 h1:MQLRM35Pp0yAyBYksjbj1nZI/w6eyRY/mWoM1sFf4kU=
 github.com/dgraph-io/ristretto v0.0.2-0.20200115201040-8f368f2f2ab3/go.mod h1:KPxhHT9ZxKefz+PCeOGsrHpl1qZ7i70dGTu2u+Ahh6E=
 github.com/dgraph-io/ristretto v0.0.3-0.20200630154024-f66de99634de h1:t0UHb5vdojIDUqktM6+xJAfScFBsVpXZmqC9dsgJmeA=
 github.com/dgraph-io/ristretto v0.0.3-0.20200630154024-f66de99634de/go.mod h1:KPxhHT9ZxKefz+PCeOGsrHpl1qZ7i70dGTu2u+Ahh6E=
+github.com/dgraph-io/ristretto v0.0.3 h1:jh22xisGBjrEVnRZ1DVTpBVQm0Xndu8sMl0CWDzSIBI=
+github.com/dgraph-io/ristretto v0.0.3/go.mod h1:KPxhHT9ZxKefz+PCeOGsrHpl1qZ7i70dGTu2u+Ahh6E=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2 h1:tdlZCpZ/P9DhczCTSixgIKmwPv6+wP5DGjqLYw5SUiA=
 github.com/dgryski/go-farm v0.0.0-20190423205320-6a90982ecee2/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
+github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13 h1:fAjc9m62+UWV/WAFKLNi6ZS0675eEUC9y3AlwSbQu1Y=
+github.com/dgryski/go-farm v0.0.0-20200201041132-a6ae2369ad13/go.mod h1:SqUrOPUnsFjfmXRMNPybcSiG0BgUW2AuFH8PAnS2iTw=
 github.com/dgryski/go-sip13 v0.0.0-20181026042036-e10d5fee7954/go.mod h1:vAd38F8PWV+bWy6jNmig1y/TA+kYO4g3RSRF0IAv0no=
 github.com/dustin/go-humanize v0.0.0-20171111073723-bb3d318650d4/go.mod h1:HtrtbFcZ19U5GC7JDqmcUSB87Iq5E25KnS6fMYU6eOk=
 github.com/dustin/go-humanize v1.0.0 h1:VSnTsYCnlFHaM2/igO1h6X3HA71jcobQuxemgkq4zYo=
@@ -228,6 +236,8 @@ github.com/golang/protobuf v1.4.2/go.mod h1:oDoupMAO8OvCJWAcko0GGGIgR6R6ocIYbsSw
 github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
 github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
+github.com/golang/snappy v0.0.2 h1:aeE13tS0IiQgFjYdoL8qN3K1N2bXXtI6Vi51/y7BpMw=
+github.com/golang/snappy v0.0.2/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.0 h1:0udJVsspx3VBr5FwtLhQQtuAsVc79tTq0ocGIPAU6qo=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
@@ -681,6 +691,8 @@ golang.org/x/net v0.0.0-20200520004742-59133d7f0dd7/go.mod h1:qpuaurCH72eLCgpAm/
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc h1:zK/HqS5bZxDptfPJNq8v7vJfXtkU7r9TLIoSr1bXaP4=
 golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
+golang.org/x/net v0.0.0-20200930145003-4acb6c075d10 h1:YfxMZzv3PjGonQYNUaeU2+DhAdqOxerQ30JFB6WgAXo=
+golang.org/x/net v0.0.0-20200930145003-4acb6c075d10/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
@@ -729,6 +741,8 @@ golang.org/x/sys v0.0.0-20200615200032-f1bc736245b1/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20200625212154-ddb9806d33ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200814200057-3d37ad5750ed h1:J22ig1FUekjjkmZUM7pTKixYm8DvrYsvrBZdunYeIuQ=
 golang.org/x/sys v0.0.0-20200814200057-3d37ad5750ed/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f h1:+Nyd8tzPX9R7BWHguqsrbFdRx3WQ/1ib8I44HXV5yTA=
+golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=

store/iavl/store.go

@@ -43,7 +43,14 @@ type Store struct {
 // store's version (id) from the provided DB. An error is returned if the version
 // fails to load.
 func LoadStore(db dbm.DB, id types.CommitID, lazyLoading bool) (types.CommitKVStore, error) {
-	tree, err := iavl.NewMutableTree(db, defaultIAVLCacheSize)
+	return LoadStoreWithInitialVersion(db, id, lazyLoading, 0)
+}
+
+// LoadStore returns an IAVL Store as a CommitKVStore setting its initialVersion
+// to the one given. Internally, it will load the store's version (id) from the
+// provided DB. An error is returned if the version fails to load.
+func LoadStoreWithInitialVersion(db dbm.DB, id types.CommitID, lazyLoading bool, initialVersion uint64) (types.CommitKVStore, error) {
+	tree, err := iavl.NewMutableTreeWithOpts(db, defaultIAVLCacheSize, &iavl.Options{InitialVersion: initialVersion})
 	if err != nil {
 		return nil, err
 	}
@@ -78,11 +85,11 @@ func UnsafeNewStore(tree *iavl.MutableTree) *Store {
 // GetImmutable returns a reference to a new store backed by an immutable IAVL
 // tree at a specific version (height) without any pruning options. This should
 // be used for querying and iteration only. If the version does not exist or has
-// been pruned, an error will be returned. Any mutable operations executed will
-// result in a panic.
+// been pruned, an empty immutable IAVL tree will be used.
+// Any mutable operations executed will result in a panic.
 func (st *Store) GetImmutable(version int64) (*Store, error) {
 	if !st.VersionExists(version) {
-		return nil, iavl.ErrVersionDoesNotExist
+		return &Store{tree: &immutableTree{&iavl.ImmutableTree{}}}, nil
 	}
 
 	iTree, err := st.tree.GetImmutable(version)
@@ -153,7 +160,6 @@ func (st *Store) CacheWrapWithTrace(w io.Writer, tc types.TraceContext) types.Ca
 
 // Implements types.KVStore.
 func (st *Store) Set(key, value []byte) {
-	defer telemetry.MeasureSince(time.Now(), "store", "iavl", "set")
 	types.AssertValidKey(key)
 	types.AssertValidValue(value)
 	st.tree.Set(key, value)

store/iavl/store_test.go

@@ -50,6 +50,62 @@ func newAlohaTree(t *testing.T, db dbm.DB) (*iavl.MutableTree, types.CommitID) {
 	return tree, types.CommitID{Version: ver, Hash: hash}
 }
 
+func TestLoadStore(t *testing.T) {
+	db := dbm.NewMemDB()
+	tree, _ := newAlohaTree(t, db)
+	store := UnsafeNewStore(tree)
+
+	// Create non-pruned height H
+	require.True(t, tree.Set([]byte("hello"), []byte("hallo")))
+	hash, verH, err := tree.SaveVersion()
+	cIDH := types.CommitID{Version: verH, Hash: hash}
+	require.Nil(t, err)
+
+	// Create pruned height Hp
+	require.True(t, tree.Set([]byte("hello"), []byte("hola")))
+	hash, verHp, err := tree.SaveVersion()
+	cIDHp := types.CommitID{Version: verHp, Hash: hash}
+	require.Nil(t, err)
+
+	// TODO: Prune this height
+
+	// Create current height Hc
+	require.True(t, tree.Set([]byte("hello"), []byte("ciao")))
+	hash, verHc, err := tree.SaveVersion()
+	cIDHc := types.CommitID{Version: verHc, Hash: hash}
+	require.Nil(t, err)
+
+	// Querying an existing store at some previous non-pruned height H
+	hStore, err := store.GetImmutable(verH)
+	require.NoError(t, err)
+	require.Equal(t, string(hStore.Get([]byte("hello"))), "hallo")
+
+	// Querying an existing store at some previous pruned height Hp
+	hpStore, err := store.GetImmutable(verHp)
+	require.NoError(t, err)
+	require.Equal(t, string(hpStore.Get([]byte("hello"))), "hola")
+
+	// Querying an existing store at current height Hc
+	hcStore, err := store.GetImmutable(verHc)
+	require.NoError(t, err)
+	require.Equal(t, string(hcStore.Get([]byte("hello"))), "ciao")
+
+	// Querying a new store at some previous non-pruned height H
+	newHStore, err := LoadStore(db, cIDH, false)
+	require.NoError(t, err)
+	require.Equal(t, string(newHStore.Get([]byte("hello"))), "hallo")
+
+	// Querying a new store at some previous pruned height Hp
+	newHpStore, err := LoadStore(db, cIDHp, false)
+	require.NoError(t, err)
+	require.Equal(t, string(newHpStore.Get([]byte("hello"))), "hola")
+
+	// Querying a new store at current height H
+	newHcStore, err := LoadStore(db, cIDHc, false)
+	require.NoError(t, err)
+	require.Equal(t, string(newHcStore.Get([]byte("hello"))), "ciao")
+}
+
 func TestGetImmutable(t *testing.T) {
 	db := dbm.NewMemDB()
 	tree, cID := newAlohaTree(t, db)
@@ -61,7 +117,7 @@ func TestGetImmutable(t *testing.T) {
 	require.Nil(t, err)
 
 	_, err = store.GetImmutable(cID.Version + 1)
-	require.Error(t, err)
+	require.NoError(t, err)
 
 	newStore, err := store.GetImmutable(cID.Version - 1)
 	require.NoError(t, err)

store/rootmulti/store.go

@@ -187,7 +187,14 @@ func (rs *Store) loadVersion(ver int64, upgrades *types.StoreUpgrades) error {
 	var newStores = make(map[types.StoreKey]types.CommitKVStore)
 
 	for key, storeParams := range rs.storesParams {
-		store, err := rs.loadCommitStoreFromParams(key, rs.getCommitID(infos, key.Name()), storeParams)
+		commitID := rs.getCommitID(infos, key.Name())
+
+		// If it has been added, set the initial version
+		if upgrades.IsAdded(key.Name()) {
+			storeParams.initialVersion = uint64(ver) + 1
+		}
+
+		store, err := rs.loadCommitStoreFromParams(key, commitID, storeParams)
 		if err != nil {
 			return errors.Wrap(err, "failed to load store")
 		}
@@ -813,7 +820,15 @@ func (rs *Store) loadCommitStoreFromParams(key types.StoreKey, id types.CommitID
 		panic("recursive MultiStores not yet supported")
 
 	case types.StoreTypeIAVL:
-		store, err := iavl.LoadStore(db, id, rs.lazyLoading)
+		var store types.CommitKVStore
+		var err error
+
+		if params.initialVersion == 0 {
+			store, err = iavl.LoadStore(db, id, rs.lazyLoading)
+		} else {
+			store, err = iavl.LoadStoreWithInitialVersion(db, id, rs.lazyLoading, params.initialVersion)
+		}
+
 		if err != nil {
 			return nil, err
 		}
@@ -868,9 +883,10 @@ func (rs *Store) buildCommitInfo(version int64) *types.CommitInfo {
 }
 
 type storeParams struct {
-	key types.StoreKey
-	db  dbm.DB
-	typ types.StoreType
+	key            types.StoreKey
+	db             dbm.DB
+	typ            types.StoreType
+	initialVersion uint64
 }
 
 func getLatestVersion(db dbm.DB) int64 {

store/rootmulti/store_test.go

@@ -79,9 +79,9 @@ func TestCacheMultiStoreWithVersion(t *testing.T) {
 	cID := ms.Commit()
 	require.Equal(t, int64(1), cID.Version)
 
-	// require failure when given an invalid or pruned version
+	// require no failure when given an invalid or pruned version
 	_, err = ms.CacheMultiStoreWithVersion(cID.Version + 1)
-	require.Error(t, err)
+	require.NoError(t, err)
 
 	// require a valid version can be cache-loaded
 	cms, err := ms.CacheMultiStoreWithVersion(cID.Version)
@@ -192,6 +192,9 @@ func TestMultistoreLoadWithUpgrade(t *testing.T) {
 	require.NotNil(t, s3)
 	s3.Set(k3, v3)
 
+	s4, _ := store.getStoreByName("store4").(types.KVStore)
+	require.Nil(t, s4)
+
 	// do one commit
 	commitID := store.Commit()
 	expectedCommitID := getExpectedCommitID(store, 1)
@@ -231,6 +234,24 @@ func TestMultistoreLoadWithUpgrade(t *testing.T) {
 	require.NotNil(t, s3)
 	require.Nil(t, s3.Get(k3)) // data was deleted
 
+	// store4 is mounted, with empty data
+	s4, _ = restore.getStoreByName("store4").(types.KVStore)
+	require.NotNil(t, s4)
+
+	iterator := s4.Iterator(nil, nil)
+
+	values := 0
+	for ; iterator.Valid(); iterator.Next() {
+		values += 1
+	}
+	require.Zero(t, values)
+
+	require.NoError(t, iterator.Close())
+
+	// write something inside store4
+	k4, v4 := []byte("fourth"), []byte("created")
+	s4.Set(k4, v4)
+
 	// store2 is no longer mounted
 	st2 := restore.getStoreByName("store2")
 	require.Nil(t, st2)
@@ -258,12 +279,16 @@ func TestMultistoreLoadWithUpgrade(t *testing.T) {
 	require.NotNil(t, rl2)
 	require.Equal(t, v2, rl2.Get(k2))
 
+	rl4, _ := reload.getStoreByName("store4").(types.KVStore)
+	require.NotNil(t, rl4)
+	require.Equal(t, v4, rl4.Get(k4))
+
 	// check commitInfo in storage
 	ci, err = getCommitInfo(db, 2)
 	require.NoError(t, err)
 	require.Equal(t, int64(2), ci.Version)
-	require.Equal(t, 3, len(ci.StoreInfos), ci.StoreInfos)
-	checkContains(t, ci.StoreInfos, []string{"store1", "restore2", "store3"})
+	require.Equal(t, 4, len(ci.StoreInfos), ci.StoreInfos)
+	checkContains(t, ci.StoreInfos, []string{"store1", "restore2", "store3", "store4"})
 }
 
 func TestParsePath(t *testing.T) {
@@ -474,7 +499,7 @@ func TestMultiStore_Pruning(t *testing.T) {
 
 			for _, v := range tc.deleted {
 				_, err := ms.CacheMultiStoreWithVersion(v)
-				require.Error(t, err, "expected error when loading height: %d", v)
+				require.NoError(t, err, "expected error when loading height: %d", v)
 			}
 		})
 	}
@@ -510,7 +535,7 @@ func TestMultiStore_PruningRestart(t *testing.T) {
 
 	for _, v := range pruneHeights {
 		_, err := ms.CacheMultiStoreWithVersion(v)
-		require.Error(t, err, "expected error when loading height: %d", v)
+		require.NoError(t, err, "expected error when loading height: %d", v)
 	}
 }
 
@@ -796,8 +821,10 @@ func newMultiStoreWithModifiedMounts(db dbm.DB, pruningOpts types.PruningOptions
 	store.MountStoreWithDB(types.NewKVStoreKey("store1"), types.StoreTypeIAVL, nil)
 	store.MountStoreWithDB(types.NewKVStoreKey("restore2"), types.StoreTypeIAVL, nil)
 	store.MountStoreWithDB(types.NewKVStoreKey("store3"), types.StoreTypeIAVL, nil)
+	store.MountStoreWithDB(types.NewKVStoreKey("store4"), types.StoreTypeIAVL, nil)
 
 	upgrades := &types.StoreUpgrades{
+		Added: []string{"store4"},
 		Renamed: []types.StoreRename{{
 			OldKey: "store2",
 			NewKey: "restore2",

store/types/store.go

@@ -9,6 +9,7 @@ import (
 
 	snapshottypes "github.com/cosmos/cosmos-sdk/snapshots/types"
 	"github.com/cosmos/cosmos-sdk/types/kv"
+	tmstrings "github.com/tendermint/tendermint/libs/strings"
 )
 
 type Store interface {
@@ -44,6 +45,7 @@ type Queryable interface {
 
 // StoreUpgrades defines a series of transformations to apply the multistore db upon load
 type StoreUpgrades struct {
+	Added   []string      `json:"added"`
 	Renamed []StoreRename `json:"renamed"`
 	Deleted []string      `json:"deleted"`
 }
@@ -63,6 +65,14 @@ type StoreRename struct {
 	NewKey string `json:"new_key"`
 }
 
+// IsDeleted returns true if the given key should be added
+func (s *StoreUpgrades) IsAdded(key string) bool {
+	if s == nil {
+		return false
+	}
+	return tmstrings.StringInSlice(key, s.Added)
+}
+
 // IsDeleted returns true if the given key should be deleted
 func (s *StoreUpgrades) IsDeleted(key string) bool {
 	if s == nil {