feat: implement object stores

CHANGELOG.md

@@ -44,6 +44,7 @@ Every module contains its own CHANGELOG.md. Please refer to the module you are i
 
 * (baseapp) [#20291](https://github.com/cosmos/cosmos-sdk/pull/20291) Simulate nested messages.
 * (client/keys) [#21829](https://github.com/cosmos/cosmos-sdk/pull/21829) Add support for importing hex key using standard input.
+* (baseapp) [#22893](https://github.com/cosmos/cosmos-sdk/pull/22893) Support mount object store in baseapp, add `ObjectStore` api in context.
 * (x/auth/ante) [#23128](https://github.com/cosmos/cosmos-sdk/pull/23128) Allow custom verifyIsOnCurve when validate tx for public key like ethsecp256k1.
 
 ### Improvements

baseapp/baseapp.go

@@ -302,6 +302,9 @@ func (app *BaseApp) MountStores(keys ...storetypes.StoreKey) {
 		case *storetypes.MemoryStoreKey:
 			app.MountStore(key, storetypes.StoreTypeMemory)
 
+		case *storetypes.ObjectStoreKey:
+			app.MountStore(key, storetypes.StoreTypeObject)
+
 		default:
 			panic(fmt.Sprintf("Unrecognized store key type :%T", key))
 		}
@@ -340,6 +343,16 @@ func (app *BaseApp) MountMemoryStores(keys map[string]*storetypes.MemoryStoreKey
 	}
 }
 
+// MountObjectStores mounts all transient object stores with the BaseApp's internal
+// commit multi-store.
+func (app *BaseApp) MountObjectStores(keys map[string]*storetypes.ObjectStoreKey) {
+	skeys := slices.Sorted(maps.Keys(keys))
+	for _, key := range skeys {
+		memKey := keys[key]
+		app.MountStore(memKey, storetypes.StoreTypeObject)
+	}
+}
+
 // MountStore mounts a store to the provided key in the BaseApp multistore,
 // using the default DB.
 func (app *BaseApp) MountStore(key storetypes.StoreKey, typ storetypes.StoreType) {

client/v2/go.mod

@@ -1,6 +1,6 @@
 module cosmossdk.io/client/v2
 
-go 1.23.3
+go 1.23.4
 
 require (
 	cosmossdk.io/api v0.8.0
@@ -65,7 +65,7 @@ require (
 	github.com/cosmos/cosmos-db v1.1.1 // indirect
 	github.com/cosmos/go-bip39 v1.0.0
 	github.com/cosmos/gogoproto v1.7.0
-	github.com/cosmos/iavl v1.3.4 // indirect
+	github.com/cosmos/iavl v1.3.5 // indirect
 	github.com/cosmos/ics23/go v0.11.0 // indirect
 	github.com/cosmos/ledger-cosmos-go v0.14.0 // indirect
 	github.com/danieljoos/wincred v1.2.1 // indirect
@@ -169,6 +169,7 @@ replace github.com/cosmos/cosmos-sdk => ./../../
 
 // TODO remove post spinning out all modules
 replace (
+	cosmossdk.io/store => ../../store
 	cosmossdk.io/x/bank => ./../../x/bank
 	cosmossdk.io/x/staking => ./../../x/staking
 )

client/v2/go.sum

@@ -22,8 +22,6 @@ cosmossdk.io/math v1.5.0 h1:sbOASxee9Zxdjd6OkzogvBZ25/hP929vdcYcBJQbkLc=
 cosmossdk.io/math v1.5.0/go.mod h1:AAwwBmUhqtk2nlku174JwSll+/DepUXW3rWIXN5q+Nw=
 cosmossdk.io/schema v1.0.0 h1:/diH4XJjpV1JQwuIozwr+A4uFuuwanFdnw2kKeiXwwQ=
 cosmossdk.io/schema v1.0.0/go.mod h1:RDAhxIeNB4bYqAlF4NBJwRrgtnciMcyyg0DOKnhNZQQ=
-cosmossdk.io/store v1.10.0-rc.1 h1:/YVPJLre7lt/QDbl90k95TLt+IvafF1sHaU6WHd/rpc=
-cosmossdk.io/store v1.10.0-rc.1/go.mod h1:eZNgZKvZRlDUk8CE3LTDVMAcSM7zLOet2S8fByQkF3s=
 cosmossdk.io/x/tx v1.0.0 h1:pUUKRvHiMUZC/MnO8v747k1lUEA1DfAq0j0y0Mqrz/o=
 cosmossdk.io/x/tx v1.0.0/go.mod h1:AXYJ47btzkcWuT1OtA3M44dv1iiYbKomtopHEbQGgH4=
 filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
@@ -117,8 +115,8 @@ github.com/cosmos/go-bip39 v1.0.0 h1:pcomnQdrdH22njcAatO0yWojsUnCO3y2tNoV1cb6hHY
 github.com/cosmos/go-bip39 v1.0.0/go.mod h1:RNJv0H/pOIVgxw6KS7QeX2a0Uo0aKUlfhZ4xuwvCdJw=
 github.com/cosmos/gogoproto v1.7.0 h1:79USr0oyXAbxg3rspGh/m4SWNyoz/GLaAh0QlCe2fro=
 github.com/cosmos/gogoproto v1.7.0/go.mod h1:yWChEv5IUEYURQasfyBW5ffkMHR/90hiHgbNgrtp4j0=
-github.com/cosmos/iavl v1.3.4 h1:A0RUAms7TZ0L6EFrrBIPg4Dy7qD9vvD5lJKUxEXURLM=
-github.com/cosmos/iavl v1.3.4/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
+github.com/cosmos/iavl v1.3.5 h1:wTDFbaa/L0FVUrwTlzMnjN3fphtKgWxgcZmTc45MZuA=
+github.com/cosmos/iavl v1.3.5/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
 github.com/cosmos/ics23/go v0.11.0 h1:jk5skjT0TqX5e5QJbEnwXIS2yI2vnmLOgpQPeM5RtnU=
 github.com/cosmos/ics23/go v0.11.0/go.mod h1:A8OjxPE67hHST4Icw94hOxxFEJMBG031xIGF/JHNIY0=
 github.com/cosmos/ledger-cosmos-go v0.14.0 h1:WfCHricT3rPbkPSVKRH+L4fQGKYHuGOK9Edpel8TYpE=

go.mod

@@ -1,4 +1,4 @@
-go 1.23.2
+go 1.23.4
 
 module github.com/cosmos/cosmos-sdk
 
@@ -81,7 +81,7 @@ require (
 	github.com/cockroachdb/redact v1.1.5 // indirect
 	github.com/cockroachdb/tokenbucket v0.0.0-20230807174530-cc333fc44b06 // indirect
 	github.com/cometbft/cometbft-db v1.0.1 // indirect
-	github.com/cosmos/iavl v1.3.4 // indirect
+	github.com/cosmos/iavl v1.3.5 // indirect
 	github.com/cosmos/ics23/go v0.11.0 // indirect
 	github.com/danieljoos/wincred v1.2.1 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
@@ -176,6 +176,7 @@ require (
 
 // TODO remove after all modules have their own go.mods
 replace (
+	cosmossdk.io/store => ./store
 	cosmossdk.io/x/bank => ./x/bank
 	cosmossdk.io/x/staking => ./x/staking
 )

go.sum

@@ -22,8 +22,6 @@ cosmossdk.io/math v1.5.0 h1:sbOASxee9Zxdjd6OkzogvBZ25/hP929vdcYcBJQbkLc=
 cosmossdk.io/math v1.5.0/go.mod h1:AAwwBmUhqtk2nlku174JwSll+/DepUXW3rWIXN5q+Nw=
 cosmossdk.io/schema v1.0.0 h1:/diH4XJjpV1JQwuIozwr+A4uFuuwanFdnw2kKeiXwwQ=
 cosmossdk.io/schema v1.0.0/go.mod h1:RDAhxIeNB4bYqAlF4NBJwRrgtnciMcyyg0DOKnhNZQQ=
-cosmossdk.io/store v1.10.0-rc.1 h1:/YVPJLre7lt/QDbl90k95TLt+IvafF1sHaU6WHd/rpc=
-cosmossdk.io/store v1.10.0-rc.1/go.mod h1:eZNgZKvZRlDUk8CE3LTDVMAcSM7zLOet2S8fByQkF3s=
 cosmossdk.io/x/tx v1.0.0 h1:pUUKRvHiMUZC/MnO8v747k1lUEA1DfAq0j0y0Mqrz/o=
 cosmossdk.io/x/tx v1.0.0/go.mod h1:AXYJ47btzkcWuT1OtA3M44dv1iiYbKomtopHEbQGgH4=
 filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
@@ -108,8 +106,8 @@ github.com/cosmos/go-bip39 v1.0.0 h1:pcomnQdrdH22njcAatO0yWojsUnCO3y2tNoV1cb6hHY
 github.com/cosmos/go-bip39 v1.0.0/go.mod h1:RNJv0H/pOIVgxw6KS7QeX2a0Uo0aKUlfhZ4xuwvCdJw=
 github.com/cosmos/gogoproto v1.7.0 h1:79USr0oyXAbxg3rspGh/m4SWNyoz/GLaAh0QlCe2fro=
 github.com/cosmos/gogoproto v1.7.0/go.mod h1:yWChEv5IUEYURQasfyBW5ffkMHR/90hiHgbNgrtp4j0=
-github.com/cosmos/iavl v1.3.4 h1:A0RUAms7TZ0L6EFrrBIPg4Dy7qD9vvD5lJKUxEXURLM=
-github.com/cosmos/iavl v1.3.4/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
+github.com/cosmos/iavl v1.3.5 h1:wTDFbaa/L0FVUrwTlzMnjN3fphtKgWxgcZmTc45MZuA=
+github.com/cosmos/iavl v1.3.5/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
 github.com/cosmos/ics23/go v0.11.0 h1:jk5skjT0TqX5e5QJbEnwXIS2yI2vnmLOgpQPeM5RtnU=
 github.com/cosmos/ics23/go v0.11.0/go.mod h1:A8OjxPE67hHST4Icw94hOxxFEJMBG031xIGF/JHNIY0=
 github.com/cosmos/keyring v1.2.0 h1:8C1lBP9xhImmIabyXW4c3vFjjLiBdGCmfLUfeZlV1Yo=

runtime/module.go

@@ -99,6 +99,7 @@ func init() {
 			ProvideKVStoreFactory,
 			ProvideTransientStoreKey,
 			ProvideMemoryStoreKey,
+			ProvideObjectStoreKey,
 			ProvideGenesisTxHandler,
 			ProvideEnvironment,
 			ProvideTransientStoreService,
@@ -242,6 +243,12 @@ func ProvideMemoryStoreKey(
 	return storeKey
 }
 
+func ProvideObjectStoreKey(key depinject.ModuleKey, app *AppBuilder) *storetypes.ObjectStoreKey {
+	storeKey := storetypes.NewObjectStoreKey(fmt.Sprintf("object:%s", key.Name()))
+	registerStoreKey(app, storeKey)
+	return storeKey
+}
+
 func ProvideModuleManager(modules map[string]appmodule.AppModule) *module.Manager {
 	return module.NewManagerFromMap(modules)
 }

runtime/store.go

@@ -163,15 +163,15 @@ func (s kvStoreAdapter) Set(key, value []byte) {
 	}
 }
 
-func (s kvStoreAdapter) Iterator(start, end []byte) store.Iterator {
+func (s kvStoreAdapter) Iterator(start, end []byte) storetypes.Iterator {
 	it, err := s.store.Iterator(start, end)
 	if err != nil {
 		panic(err)
 	}
 	return it
 }
 
-func (s kvStoreAdapter) ReverseIterator(start, end []byte) store.Iterator {
+func (s kvStoreAdapter) ReverseIterator(start, end []byte) storetypes.Iterator {
 	it, err := s.store.ReverseIterator(start, end)
 	if err != nil {
 		panic(err)

server/v2/cometbft/go.mod

@@ -1,6 +1,6 @@
 module cosmossdk.io/server/v2/cometbft
 
-go 1.23.2
+go 1.23.4
 
 replace (
 	cosmossdk.io/server/v2 => ../
@@ -74,7 +74,7 @@ require (
 	github.com/cosmos/btcutil v1.0.5 // indirect
 	github.com/cosmos/cosmos-proto v1.0.0-beta.5 // indirect
 	github.com/cosmos/go-bip39 v1.0.0 // indirect
-	github.com/cosmos/iavl v1.3.4 // indirect
+	github.com/cosmos/iavl v1.3.5 // indirect
 	github.com/cosmos/iavl/v2 v2.0.0-alpha.4 // indirect
 	github.com/cosmos/ics23/go v0.11.0 // indirect
 	github.com/cosmos/ledger-cosmos-go v0.14.0 // indirect
@@ -184,3 +184,6 @@ require (
 	gotest.tools/v3 v3.5.1 // indirect
 	pgregory.net/rapid v1.1.0 // indirect
 )
+
+// TODO remove post spinning out all modules
+replace cosmossdk.io/store => ../../../store

server/v2/cometbft/go.sum

@@ -24,8 +24,6 @@ cosmossdk.io/math v1.5.0 h1:sbOASxee9Zxdjd6OkzogvBZ25/hP929vdcYcBJQbkLc=
 cosmossdk.io/math v1.5.0/go.mod h1:AAwwBmUhqtk2nlku174JwSll+/DepUXW3rWIXN5q+Nw=
 cosmossdk.io/schema v1.0.0 h1:/diH4XJjpV1JQwuIozwr+A4uFuuwanFdnw2kKeiXwwQ=
 cosmossdk.io/schema v1.0.0/go.mod h1:RDAhxIeNB4bYqAlF4NBJwRrgtnciMcyyg0DOKnhNZQQ=
-cosmossdk.io/store v1.10.0-rc.1 h1:/YVPJLre7lt/QDbl90k95TLt+IvafF1sHaU6WHd/rpc=
-cosmossdk.io/store v1.10.0-rc.1/go.mod h1:eZNgZKvZRlDUk8CE3LTDVMAcSM7zLOet2S8fByQkF3s=
 cosmossdk.io/x/tx v1.0.0 h1:pUUKRvHiMUZC/MnO8v747k1lUEA1DfAq0j0y0Mqrz/o=
 cosmossdk.io/x/tx v1.0.0/go.mod h1:AXYJ47btzkcWuT1OtA3M44dv1iiYbKomtopHEbQGgH4=
 filippo.io/edwards25519 v1.1.0 h1:FNf4tywRC1HmFuKW5xopWpigGjJKiJSV0Cqo0cJWDaA=
@@ -127,8 +125,8 @@ github.com/cosmos/go-bip39 v1.0.0 h1:pcomnQdrdH22njcAatO0yWojsUnCO3y2tNoV1cb6hHY
 github.com/cosmos/go-bip39 v1.0.0/go.mod h1:RNJv0H/pOIVgxw6KS7QeX2a0Uo0aKUlfhZ4xuwvCdJw=
 github.com/cosmos/gogoproto v1.7.0 h1:79USr0oyXAbxg3rspGh/m4SWNyoz/GLaAh0QlCe2fro=
 github.com/cosmos/gogoproto v1.7.0/go.mod h1:yWChEv5IUEYURQasfyBW5ffkMHR/90hiHgbNgrtp4j0=
-github.com/cosmos/iavl v1.3.4 h1:A0RUAms7TZ0L6EFrrBIPg4Dy7qD9vvD5lJKUxEXURLM=
-github.com/cosmos/iavl v1.3.4/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
+github.com/cosmos/iavl v1.3.5 h1:wTDFbaa/L0FVUrwTlzMnjN3fphtKgWxgcZmTc45MZuA=
+github.com/cosmos/iavl v1.3.5/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
 github.com/cosmos/iavl-bench/bench v0.0.4 h1:J6zQPiBqF4CXMM3QBsLqZgQEBGY0taX85vLIZMhmAfQ=
 github.com/cosmos/iavl-bench/bench v0.0.4/go.mod h1:j2rLae77EffacWcp7mmj3Uaa4AOAmZA7ymvhsuBQKKI=
 github.com/cosmos/iavl/v2 v2.0.0-alpha.4 h1:PfpQt7xl4hojw2UFS2JdJppJnx8sjlmcxRQ7Hxk7Cl0=

simapp/v2/go.mod

@@ -103,7 +103,7 @@ require (
 	github.com/cosmos/go-bip39 v1.0.0 // indirect
 	github.com/cosmos/gogogateway v1.2.0 // indirect
 	github.com/cosmos/gogoproto v1.7.0 // indirect
-	github.com/cosmos/iavl v1.3.4 // indirect
+	github.com/cosmos/iavl v1.3.5 // indirect
 	github.com/cosmos/ics23/go v0.11.0 // indirect
 	github.com/cosmos/ledger-cosmos-go v0.14.0 // indirect
 	github.com/creachadair/atomicfile v0.3.7 // indirect
@@ -303,5 +303,6 @@ replace (
 	cosmossdk.io/server/v2/appmanager => ../../server/v2/appmanager
 	cosmossdk.io/server/v2/cometbft => ../../server/v2/cometbft
 	cosmossdk.io/server/v2/stf => ../../server/v2/stf
+	cosmossdk.io/store => ../../store
 	cosmossdk.io/store/v2 => ../../store/v2
 )

simapp/v2/go.sum

@@ -212,8 +212,6 @@ cosmossdk.io/math v1.5.0 h1:sbOASxee9Zxdjd6OkzogvBZ25/hP929vdcYcBJQbkLc=
 cosmossdk.io/math v1.5.0/go.mod h1:AAwwBmUhqtk2nlku174JwSll+/DepUXW3rWIXN5q+Nw=
 cosmossdk.io/schema v1.0.0 h1:/diH4XJjpV1JQwuIozwr+A4uFuuwanFdnw2kKeiXwwQ=
 cosmossdk.io/schema v1.0.0/go.mod h1:RDAhxIeNB4bYqAlF4NBJwRrgtnciMcyyg0DOKnhNZQQ=
-cosmossdk.io/store v1.10.0-rc.1.0.20241218084712-ca559989da43 h1:glZ6MpmD+5AhwJYV4jzx+rn7cgUB2owHgk9o+93luz0=
-cosmossdk.io/store v1.10.0-rc.1.0.20241218084712-ca559989da43/go.mod h1:XCWpgfueHSBY+B7Cf2Aq/CcsU+6XoFH+EmseCKglFrU=
 cosmossdk.io/x/tx v1.0.0 h1:pUUKRvHiMUZC/MnO8v747k1lUEA1DfAq0j0y0Mqrz/o=
 cosmossdk.io/x/tx v1.0.0/go.mod h1:AXYJ47btzkcWuT1OtA3M44dv1iiYbKomtopHEbQGgH4=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
@@ -344,8 +342,8 @@ github.com/cosmos/gogogateway v1.2.0/go.mod h1:iQpLkGWxYcnCdz5iAdLcRBSw3h7NXeOkZ
 github.com/cosmos/gogoproto v1.4.2/go.mod h1:cLxOsn1ljAHSV527CHOtaIP91kK6cCrZETRBrkzItWU=
 github.com/cosmos/gogoproto v1.7.0 h1:79USr0oyXAbxg3rspGh/m4SWNyoz/GLaAh0QlCe2fro=
 github.com/cosmos/gogoproto v1.7.0/go.mod h1:yWChEv5IUEYURQasfyBW5ffkMHR/90hiHgbNgrtp4j0=
-github.com/cosmos/iavl v1.3.4 h1:A0RUAms7TZ0L6EFrrBIPg4Dy7qD9vvD5lJKUxEXURLM=
-github.com/cosmos/iavl v1.3.4/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
+github.com/cosmos/iavl v1.3.5 h1:wTDFbaa/L0FVUrwTlzMnjN3fphtKgWxgcZmTc45MZuA=
+github.com/cosmos/iavl v1.3.5/go.mod h1:T6SfBcyhulVIY2G/ZtAtQm/QiJvsuhIos52V4dWYk88=
 github.com/cosmos/iavl-bench/bench v0.0.4 h1:J6zQPiBqF4CXMM3QBsLqZgQEBGY0taX85vLIZMhmAfQ=
 github.com/cosmos/iavl-bench/bench v0.0.4/go.mod h1:j2rLae77EffacWcp7mmj3Uaa4AOAmZA7ymvhsuBQKKI=
 github.com/cosmos/iavl/v2 v2.0.0-alpha.4 h1:PfpQt7xl4hojw2UFS2JdJppJnx8sjlmcxRQ7Hxk7Cl0=

store/CHANGELOG.md

@@ -33,6 +33,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## v1.10.0 (December 13, 2024)
 
+### Features
+
+* [#22893](https://github.com/cosmos/cosmos-sdk/pull/22893) Support mount object store in baseapp, add `ObjectStore` api in context.
+
 ### Improvements
 
 * [#22305](https://github.com/cosmos/cosmos-sdk/pull/22305) Add `LatestVersion` to the `Committer` interface to get the latest version of the store.

store/cachekv/internal/mergeiterator.go

@@ -14,21 +14,24 @@ import (
 // cache shadows (overrides) the parent.
 //
 // TODO: Optimize by memoizing.
-type cacheMergeIterator struct {
-	parent    types.Iterator
-	cache     types.Iterator
+type cacheMergeIterator[V any] struct {
+	parent    types.GIterator[V]
+	cache     types.GIterator[V]
 	ascending bool
 
 	valid bool
+
+	isZero func(V) bool
 }
 
-var _ types.Iterator = (*cacheMergeIterator)(nil)
+var _ types.Iterator = (*cacheMergeIterator[[]byte])(nil)
 
-func NewCacheMergeIterator(parent, cache types.Iterator, ascending bool) types.Iterator {
-	iter := &cacheMergeIterator{
+func NewCacheMergeIterator[V any](parent, cache types.GIterator[V], ascending bool, isZero func(V) bool) types.GIterator[V] {
+	iter := &cacheMergeIterator[V]{
 		parent:    parent,
 		cache:     cache,
 		ascending: ascending,
+		isZero:    isZero,
 	}
 
 	iter.valid = iter.skipUntilExistsOrInvalid()
@@ -37,17 +40,17 @@ func NewCacheMergeIterator(parent, cache types.Iterator, ascending bool) types.I
 
 // Domain implements Iterator.
 // Returns parent domain because cache and parent domains are the same.
-func (iter *cacheMergeIterator) Domain() (start, end []byte) {
+func (iter *cacheMergeIterator[V]) Domain() (start, end []byte) {
 	return iter.parent.Domain()
 }
 
 // Valid implements Iterator.
-func (iter *cacheMergeIterator) Valid() bool {
+func (iter *cacheMergeIterator[V]) Valid() bool {
 	return iter.valid
 }
 
 // Next implements Iterator
-func (iter *cacheMergeIterator) Next() {
+func (iter *cacheMergeIterator[V]) Next() {
 	iter.assertValid()
 
 	switch {
@@ -74,7 +77,7 @@ func (iter *cacheMergeIterator) Next() {
 }
 
 // Key implements Iterator
-func (iter *cacheMergeIterator) Key() []byte {
+func (iter *cacheMergeIterator[V]) Key() []byte {
 	iter.assertValid()
 
 	// If parent is invalid, get the cache key.
@@ -104,7 +107,7 @@ func (iter *cacheMergeIterator) Key() []byte {
 }
 
 // Value implements Iterator
-func (iter *cacheMergeIterator) Value() []byte {
+func (iter *cacheMergeIterator[V]) Value() V {
 	iter.assertValid()
 
 	// If parent is invalid, get the cache value.
@@ -134,7 +137,7 @@ func (iter *cacheMergeIterator) Value() []byte {
 }
 
 // Close implements Iterator
-func (iter *cacheMergeIterator) Close() error {
+func (iter *cacheMergeIterator[V]) Close() error {
 	err1 := iter.cache.Close()
 	if err := iter.parent.Close(); err != nil {
 		return err
@@ -145,7 +148,7 @@ func (iter *cacheMergeIterator) Close() error {
 
 // Error returns an error if the cacheMergeIterator is invalid defined by the
 // Valid method.
-func (iter *cacheMergeIterator) Error() error {
+func (iter *cacheMergeIterator[V]) Error() error {
 	if !iter.Valid() {
 		return errors.New("invalid cacheMergeIterator")
 	}
@@ -155,14 +158,14 @@ func (iter *cacheMergeIterator) Error() error {
 
 // If not valid, panics.
 // NOTE: May have side-effect of iterating over cache.
-func (iter *cacheMergeIterator) assertValid() {
+func (iter *cacheMergeIterator[V]) assertValid() {
 	if err := iter.Error(); err != nil {
 		panic(err)
 	}
 }
 
 // Like bytes.Compare but opposite if not ascending.
-func (iter *cacheMergeIterator) compare(a, b []byte) int {
+func (iter *cacheMergeIterator[V]) compare(a, b []byte) int {
 	if iter.ascending {
 		return bytes.Compare(a, b)
 	}
@@ -175,9 +178,9 @@ func (iter *cacheMergeIterator) compare(a, b []byte) int {
 // If the current cache item is not a delete item, does nothing.
 // If `until` is nil, there is no limit, and cache may end up invalid.
 // CONTRACT: cache is valid.
-func (iter *cacheMergeIterator) skipCacheDeletes(until []byte) {
+func (iter *cacheMergeIterator[V]) skipCacheDeletes(until []byte) {
 	for iter.cache.Valid() &&
-		iter.cache.Value() == nil &&
+		iter.isZero(iter.cache.Value()) &&
 		(until == nil || iter.compare(iter.cache.Key(), until) < 0) {
 		iter.cache.Next()
 	}
@@ -186,7 +189,7 @@ func (iter *cacheMergeIterator) skipCacheDeletes(until []byte) {
 // Fast forwards cache (or parent+cache in case of deleted items) until current
 // item exists, or until iterator becomes invalid.
 // Returns whether the iterator is valid.
-func (iter *cacheMergeIterator) skipUntilExistsOrInvalid() bool {
+func (iter *cacheMergeIterator[V]) skipUntilExistsOrInvalid() bool {
 	for {
 		// If parent is invalid, fast-forward cache.
 		if !iter.parent.Valid() {
@@ -211,7 +214,7 @@ func (iter *cacheMergeIterator) skipUntilExistsOrInvalid() bool {
 		case 0: // parent == cache.
 			// Skip over if cache item is a delete.
 			valueC := iter.cache.Value()
-			if valueC == nil {
+			if iter.isZero(valueC) {
 				iter.parent.Next()
 				iter.cache.Next()
 
@@ -223,7 +226,7 @@ func (iter *cacheMergeIterator) skipUntilExistsOrInvalid() bool {
 		case 1: // cache < parent
 			// Skip over if cache item is a delete.
 			valueC := iter.cache.Value()
-			if valueC == nil {
+			if iter.isZero(valueC) {
 				iter.skipCacheDeletes(keyP)
 				continue
 			}