diff --git a/internal/unionstore/arena/arena.go b/internal/unionstore/arena/arena.go
index 3e3cec489..84075020e 100644
--- a/internal/unionstore/arena/arena.go
+++ b/internal/unionstore/arena/arena.go
@@ -259,7 +259,7 @@ type KeyFlagsGetter interface {
 
 // VlogMemDB is the interface of the memory buffer which supports vlog to revert node and inspect node.
 type VlogMemDB[G KeyFlagsGetter] interface {
-	RevertNode(hdr *MemdbVlogHdr)
+	RevertVAddr(hdr *MemdbVlogHdr)
 	InspectNode(addr MemdbArenaAddr) (G, MemdbArenaAddr)
 }
 
@@ -351,7 +351,7 @@ func (l *MemdbVlog[G, M]) RevertToCheckpoint(m M, cp *MemDBCheckpoint) {
 		block := l.blocks[cursor.blocks-1].buf
 		var hdr MemdbVlogHdr
 		hdr.load(block[hdrOff:])
-		m.RevertNode(&hdr)
+		m.RevertVAddr(&hdr)
 		l.moveBackCursor(&cursor, &hdr)
 	}
 }
diff --git a/internal/unionstore/arena/arena_test.go b/internal/unionstore/arena/arena_test.go
index 5816481bf..3c67054bf 100644
--- a/internal/unionstore/arena/arena_test.go
+++ b/internal/unionstore/arena/arena_test.go
@@ -42,7 +42,7 @@ import (
 
 type dummyMemDB struct{}
 
-func (m *dummyMemDB) RevertNode(hdr *MemdbVlogHdr) {}
+func (m *dummyMemDB) RevertVAddr(hdr *MemdbVlogHdr) {}
 func (m *dummyMemDB) InspectNode(addr MemdbArenaAddr) (KeyFlagsGetter, MemdbArenaAddr) {
 	return nil, NullAddr
 }
diff --git a/internal/unionstore/art/art.go b/internal/unionstore/art/art.go
index 17e826327..29f0ea53e 100644
--- a/internal/unionstore/art/art.go
+++ b/internal/unionstore/art/art.go
@@ -16,6 +16,7 @@
 package art
 
 import (
+	"fmt"
 	"math"
 
 	tikverr "github.com/tikv/client-go/v2/error"
@@ -76,7 +77,7 @@ func (t *ART) GetFlags(key []byte) (kv.KeyFlags, error) {
 	if leaf.vAddr.IsNull() && leaf.isDeleted() {
 		return 0, tikverr.ErrNotExist
 	}
-	return leaf.getKeyFlags(), nil
+	return leaf.GetKeyFlags(), nil
 }
 
 func (t *ART) Set(key artKey, value []byte, ops ...kv.FlagsOp) error {
@@ -324,8 +325,8 @@ func (t *ART) newLeaf(key artKey) (artNode, *artLeaf) {
 }
 
 func (t *ART) setValue(addr arena.MemdbArenaAddr, l *artLeaf, value []byte, ops []kv.FlagsOp) {
-	flags := l.getKeyFlags()
-	if flags == 0 && l.vAddr.IsNull() {
+	flags := l.GetKeyFlags()
+	if flags == 0 && l.vAddr.IsNull() || l.isDeleted() {
 		t.len++
 		t.size += int(l.klen)
 	}
@@ -373,12 +374,12 @@ func (t *ART) trySwapValue(addr arena.MemdbArenaAddr, value []byte) (int, bool)
 }
 
 func (t *ART) Dirty() bool {
-	panic("unimplemented")
+	return t.dirty
 }
 
 // Mem returns the memory usage of MemBuffer.
 func (t *ART) Mem() uint64 {
-	panic("unimplemented")
+	return t.allocator.nodeAllocator.Capacity() + t.allocator.vlogAllocator.Capacity()
 }
 
 // Len returns the count of entries in the MemBuffer.
@@ -392,51 +393,97 @@ func (t *ART) Size() int {
 }
 
 func (t *ART) checkpoint() arena.MemDBCheckpoint {
-	panic("unimplemented")
+	return t.allocator.vlogAllocator.Checkpoint()
 }
 
-func (t *ART) RevertNode(hdr *arena.MemdbVlogHdr) {
-	panic("unimplemented")
+func (t *ART) RevertVAddr(hdr *arena.MemdbVlogHdr) {
+	lf := t.allocator.getLeaf(hdr.NodeAddr)
+	if lf == nil {
+		panic("revert an invalid node")
+	}
+	lf.vAddr = hdr.OldValue
+	t.size -= int(hdr.ValueLen)
+	if hdr.OldValue.IsNull() {
+		keptFlags := lf.GetKeyFlags()
+		keptFlags = keptFlags.AndPersistent()
+		if keptFlags == 0 {
+			lf.markDelete()
+			t.len--
+			t.size -= int(lf.klen)
+		} else {
+			lf.setKeyFlags(keptFlags)
+		}
+	} else {
+		t.size += len(t.allocator.vlogAllocator.GetValue(hdr.OldValue))
+	}
 }
 
 func (t *ART) InspectNode(addr arena.MemdbArenaAddr) (*artLeaf, arena.MemdbArenaAddr) {
-	panic("unimplemented")
+	lf := t.allocator.getLeaf(addr)
+	return lf, lf.vAddr
 }
 
 // Checkpoint returns a checkpoint of ART.
 func (t *ART) Checkpoint() *arena.MemDBCheckpoint {
-	panic("unimplemented")
+	cp := t.allocator.vlogAllocator.Checkpoint()
+	return &cp
 }
 
 // RevertToCheckpoint reverts the ART to the checkpoint.
 func (t *ART) RevertToCheckpoint(cp *arena.MemDBCheckpoint) {
-	panic("unimplemented")
+	t.allocator.vlogAllocator.RevertToCheckpoint(t, cp)
+	t.allocator.vlogAllocator.Truncate(cp)
+	t.allocator.vlogAllocator.OnMemChange()
 }
 
 func (t *ART) Stages() []arena.MemDBCheckpoint {
-	panic("unimplemented")
+	return t.stages
 }
 
 func (t *ART) Staging() int {
-	return 0
+	t.stages = append(t.stages, t.checkpoint())
+	return len(t.stages)
 }
 
 func (t *ART) Release(h int) {
+	if h == 0 {
+		// 0 is the invalid and no-effect handle.
+		return
+	}
+	if h != len(t.stages) {
+		panic("cannot release staging buffer")
+	}
+	if h == 1 {
+		tail := t.checkpoint()
+		if !t.stages[0].IsSamePosition(&tail) {
+			t.dirty = true
+		}
+	}
+	t.stages = t.stages[:h-1]
 }
 
 func (t *ART) Cleanup(h int) {
-}
-
-func (t *ART) revertToCheckpoint(cp *arena.MemDBCheckpoint) {
-	panic("unimplemented")
-}
-
-func (t *ART) moveBackCursor(cursor *arena.MemDBCheckpoint, hdr *arena.MemdbVlogHdr) {
-	panic("unimplemented")
-}
+	if h == 0 {
+		// 0 is the invalid and no-effect handle.
+		return
+	}
+	if h > len(t.stages) {
+		return
+	}
+	if h < len(t.stages) {
+		panic(fmt.Sprintf("cannot cleanup staging buffer, h=%v, len(db.stages)=%v", h, len(t.stages)))
+	}
 
-func (t *ART) truncate(snap *arena.MemDBCheckpoint) {
-	panic("unimplemented")
+	cp := &t.stages[h-1]
+	if !t.vlogInvalid {
+		curr := t.checkpoint()
+		if !curr.IsSamePosition(cp) {
+			t.allocator.vlogAllocator.RevertToCheckpoint(t, cp)
+			t.allocator.vlogAllocator.Truncate(cp)
+		}
+	}
+	t.stages = t.stages[:h-1]
+	t.allocator.vlogAllocator.OnMemChange()
 }
 
 // Reset resets the MemBuffer to initial states.
@@ -459,7 +506,10 @@ func (t *ART) DiscardValues() {
 
 // InspectStage used to inspect the value updates in the given stage.
 func (t *ART) InspectStage(handle int, f func([]byte, kv.KeyFlags, []byte)) {
-	panic("unimplemented")
+	idx := handle - 1
+	tail := t.allocator.vlogAllocator.Checkpoint()
+	head := t.stages[idx]
+	t.allocator.vlogAllocator.InspectKVInLog(t, &head, &tail, f)
 }
 
 // SelectValueHistory select the latest value which makes `predicate` returns true from the modification history.
diff --git a/internal/unionstore/art/art_node.go b/internal/unionstore/art/art_node.go
index 0c4ee9090..f94794ce6 100644
--- a/internal/unionstore/art/art_node.go
+++ b/internal/unionstore/art/art_node.go
@@ -265,11 +265,6 @@ func (l *artLeaf) getKeyDepth(depth uint32) []byte {
 	return unsafe.Slice((*byte)(base), int(l.klen)-int(depth))
 }
 
-// GetKeyFlags gets the flags of the leaf
-func (l *artLeaf) GetKeyFlags() kv.KeyFlags {
-	panic("unimplemented")
-}
-
 func (l *artLeaf) match(depth uint32, key artKey) bool {
 	return bytes.Equal(l.getKeyDepth(depth), key[depth:])
 }
@@ -278,7 +273,8 @@ func (l *artLeaf) setKeyFlags(flags kv.KeyFlags) {
 	l.flags = uint16(flags) & flagMask
 }
 
-func (l *artLeaf) getKeyFlags() kv.KeyFlags {
+// GetKeyFlags gets the flags of the leaf
+func (l *artLeaf) GetKeyFlags() kv.KeyFlags {
 	return kv.KeyFlags(l.flags & flagMask)
 }
 
@@ -288,8 +284,6 @@ const (
 )
 
 // markDelete marks the artLeaf as deleted
-//
-//nolint:unused
 func (l *artLeaf) markDelete() {
 	l.flags = deleteFlag
 }
diff --git a/internal/unionstore/memdb_norace_test.go b/internal/unionstore/memdb_norace_test.go
index f669ef798..ffd4b3d41 100644
--- a/internal/unionstore/memdb_norace_test.go
+++ b/internal/unionstore/memdb_norace_test.go
@@ -38,6 +38,7 @@
 package unionstore
 
 import (
+	"context"
 	rand2 "crypto/rand"
 	"encoding/binary"
 	"math/rand"
@@ -166,3 +167,41 @@ func testRandomDeriveRecur(t *testing.T, db *MemDB, golden *leveldb.DB, depth in
 
 	return opLog
 }
+
+func TestRandomAB(t *testing.T) {
+	testRandomAB(t, newRbtDBWithContext(), newArtDBWithContext())
+}
+
+func testRandomAB(t *testing.T, bufferA, bufferB MemBuffer) {
+	require := require.New(t)
+
+	const cnt = 50000
+	keys := make([][]byte, cnt)
+	for i := 0; i < cnt; i++ {
+		h := bufferA.Staging()
+		require.Equal(h, bufferB.Staging())
+
+		keys[i] = make([]byte, rand.Intn(19)+1)
+		rand2.Read(keys[i])
+
+		bufferA.Set(keys[i], keys[i])
+		bufferB.Set(keys[i], keys[i])
+
+		if i%2 == 0 {
+			bufferA.Cleanup(h)
+			bufferB.Cleanup(h)
+		} else {
+			bufferA.Release(h)
+			bufferB.Release(h)
+		}
+
+		require.Equal(bufferA.Dirty(), bufferB.Dirty())
+		require.Equal(bufferA.Len(), bufferB.Len())
+		require.Equal(bufferA.Size(), bufferB.Size(), i)
+		key := keys[rand.Intn(i+1)]
+		v1, err1 := bufferA.Get(context.Background(), key)
+		v2, err2 := bufferB.Get(context.Background(), key)
+		require.Equal(err1, err2)
+		require.Equal(v1, v2)
+	}
+}
diff --git a/internal/unionstore/memdb_test.go b/internal/unionstore/memdb_test.go
index 62ae308d1..f3996de86 100644
--- a/internal/unionstore/memdb_test.go
+++ b/internal/unionstore/memdb_test.go
@@ -392,6 +392,7 @@ func testReset(t *testing.T, db interface {
 
 func TestInspectStage(t *testing.T) {
 	testInspectStage(t, newRbtDBWithContext())
+	testInspectStage(t, newArtDBWithContext())
 }
 
 func testInspectStage(t *testing.T, db MemBuffer) {
@@ -449,6 +450,7 @@ func testInspectStage(t *testing.T, db MemBuffer) {
 
 func TestDirty(t *testing.T) {
 	testDirty(t, func() MemBuffer { return newRbtDBWithContext() })
+	testDirty(t, func() MemBuffer { return newArtDBWithContext() })
 }
 
 func testDirty(t *testing.T, createDb func() MemBuffer) {
@@ -782,8 +784,12 @@ func TestNewIteratorMin(t *testing.T) {
 }
 
 func TestMemDBStaging(t *testing.T) {
+	testMemDBStaging(t, newRbtDBWithContext())
+	testMemDBStaging(t, newArtDBWithContext())
+}
+
+func testMemDBStaging(t *testing.T, buffer MemBuffer) {
 	assert := assert.New(t)
-	buffer := NewMemDB()
 	err := buffer.Set([]byte("x"), make([]byte, 2))
 	assert.Nil(err)
 
@@ -809,6 +815,117 @@ func TestMemDBStaging(t *testing.T) {
 	assert.Equal(len(v), 2)
 }
 
+func TestMemDBMultiLevelStaging(t *testing.T) {
+	testMemDBMultiLevelStaging(t, newRbtDBWithContext())
+	testMemDBMultiLevelStaging(t, newArtDBWithContext())
+}
+
+func testMemDBMultiLevelStaging(t *testing.T, buffer MemBuffer) {
+	assert := assert.New(t)
+
+	key := []byte{0}
+	for i := 0; i < 100; i++ {
+		assert.Equal(i+1, buffer.Staging())
+		buffer.Set(key, []byte{byte(i)})
+		v, err := buffer.Get(context.Background(), key)
+		assert.Nil(err)
+		assert.Equal(v, []byte{byte(i)})
+	}
+
+	for i := 99; i >= 0; i-- {
+		expect := i
+		if i%2 == 1 {
+			expect = i - 1
+			buffer.Cleanup(i + 1)
+		} else {
+			buffer.Release(i + 1)
+		}
+		v, err := buffer.Get(context.Background(), key)
+		assert.Nil(err)
+		assert.Equal(v, []byte{byte(expect)})
+	}
+}
+
+func TestInvalidStagingHandle(t *testing.T) {
+	testInvalidStagingHandle(t, newRbtDBWithContext())
+	testInvalidStagingHandle(t, newArtDBWithContext())
+}
+
+func testInvalidStagingHandle(t *testing.T, buffer MemBuffer) {
+	// handle == 0 takes no effect
+	// MemBuffer.Release only accept the latest handle
+	// MemBuffer.Cleanup accept handle large or equal than the latest handle, but only takes effect when handle is the latest handle.
+	assert := assert.New(t)
+
+	// test MemBuffer.Release
+	h1 := buffer.Staging()
+	assert.Positive(h1)
+	h2 := buffer.Staging()
+	assert.Positive(h2)
+	assert.Panics(func() {
+		buffer.Release(h2 + 1)
+	})
+	assert.Panics(func() {
+		buffer.Release(h2 - 1)
+	})
+	buffer.Release(0)
+	buffer.Release(h2)
+	buffer.Release(0)
+	buffer.Release(h1)
+	buffer.Release(0)
+
+	// test MemBuffer.Cleanup
+	h1 = buffer.Staging()
+	assert.Positive(h1)
+	h2 = buffer.Staging()
+	assert.Positive(h2)
+	buffer.Cleanup(h2 + 1) // Cleanup is ok even if the handle is greater than the existing handles.
+	assert.Panics(func() {
+		buffer.Cleanup(h2 - 1)
+	})
+	buffer.Cleanup(0)
+	buffer.Cleanup(h2)
+	buffer.Cleanup(0)
+	buffer.Cleanup(h1)
+	buffer.Cleanup(0)
+}
+
+func TestMemDBCheckpoint(t *testing.T) {
+	testMemDBCheckpoint(t, newRbtDBWithContext())
+	testMemDBCheckpoint(t, newArtDBWithContext())
+}
+
+func testMemDBCheckpoint(t *testing.T, buffer MemBuffer) {
+	assert := assert.New(t)
+	cp1 := buffer.Checkpoint()
+
+	buffer.Set([]byte("x"), []byte("x"))
+
+	cp2 := buffer.Checkpoint()
+	buffer.Set([]byte("y"), []byte("y"))
+
+	h := buffer.Staging()
+	buffer.Set([]byte("z"), []byte("z"))
+	buffer.Release(h)
+
+	for _, k := range []string{"x", "y", "z"} {
+		v, _ := buffer.Get(context.Background(), []byte(k))
+		assert.Equal(v, []byte(k))
+	}
+
+	buffer.RevertToCheckpoint(cp2)
+	v, _ := buffer.Get(context.Background(), []byte("x"))
+	assert.Equal(v, []byte("x"))
+	for _, k := range []string{"y", "z"} {
+		_, err := buffer.Get(context.Background(), []byte(k))
+		assert.NotNil(err)
+	}
+
+	buffer.RevertToCheckpoint(cp1)
+	_, err := buffer.Get(context.Background(), []byte("x"))
+	assert.NotNil(err)
+}
+
 func TestBufferLimit(t *testing.T) {
 	testBufferLimit(t, newRbtDBWithContext())
 }
@@ -897,3 +1014,36 @@ func testSnapshotGetIter(t *testing.T, db MemBuffer) {
 		assert.Equal(reverseIter.Value(), []byte{byte(50)})
 	}
 }
+
+func TestCleanupKeepPersistentFlag(t *testing.T) {
+	testCleanupKeepPersistentFlag(t, newRbtDBWithContext())
+	testCleanupKeepPersistentFlag(t, newArtDBWithContext())
+}
+
+func testCleanupKeepPersistentFlag(t *testing.T, db MemBuffer) {
+	assert := assert.New(t)
+	persistentFlag := kv.SetKeyLocked
+	nonPersistentFlag := kv.SetPresumeKeyNotExists
+
+	h := db.Staging()
+	db.SetWithFlags([]byte{1}, []byte{1}, persistentFlag)
+	db.SetWithFlags([]byte{2}, []byte{2}, nonPersistentFlag)
+	db.SetWithFlags([]byte{3}, []byte{3}, persistentFlag, nonPersistentFlag)
+	db.Cleanup(h)
+
+	for _, key := range [][]byte{{1}, {2}, {3}} {
+		// the values are reverted by MemBuffer.Cleanup
+		_, err := db.Get(context.Background(), key)
+		assert.NotNil(err)
+	}
+
+	flag, err := db.GetFlags([]byte{1})
+	assert.Nil(err)
+	assert.True(flag.HasLocked())
+	_, err = db.GetFlags([]byte{2})
+	assert.NotNil(err)
+	flag, err = db.GetFlags([]byte{3})
+	assert.Nil(err)
+	assert.True(flag.HasLocked())
+	assert.False(flag.HasPresumeKeyNotExists())
+}
diff --git a/internal/unionstore/rbt/rbt.go b/internal/unionstore/rbt/rbt.go
index 6dd9cecf9..40b3234c3 100644
--- a/internal/unionstore/rbt/rbt.go
+++ b/internal/unionstore/rbt/rbt.go
@@ -111,7 +111,7 @@ func (db *RBT) checkKeyInCache(key []byte) (MemdbNodeAddr, bool) {
 	return nullNodeAddr, false
 }
 
-func (db *RBT) RevertNode(hdr *arena.MemdbVlogHdr) {
+func (db *RBT) RevertVAddr(hdr *arena.MemdbVlogHdr) {
 	node := db.getNode(hdr.NodeAddr)
 	node.vptr = hdr.OldValue
 	db.size -= int(hdr.ValueLen)
@@ -150,6 +150,10 @@ func (db *RBT) Staging() int {
 
 // Release publish all modifications in the latest staging buffer to upper level.
 func (db *RBT) Release(h int) {
+	if h == 0 {
+		// 0 is the invalid and no-effect handle.
+		return
+	}
 	if h != len(db.stages) {
 		// This should never happens in production environment.
 		// Use panic to make debug easier.
@@ -168,6 +172,10 @@ func (db *RBT) Release(h int) {
 // Cleanup cleanup the resources referenced by the StagingHandle.
 // If the changes are not published by `Release`, they will be discarded.
 func (db *RBT) Cleanup(h int) {
+	if h == 0 {
+		// 0 is the invalid and no-effect handle.
+		return
+	}
 	if h > len(db.stages) {
 		return
 	}