*: add a memdb memory tracker

DEPS.bzl

@@ -2915,8 +2915,8 @@ def go_deps():
         name = "com_github_pingcap_kvproto",
         build_file_proto_mode = "disable_global",
         importpath = "github.com/pingcap/kvproto",
-        sum = "h1:HyWSOT/drBEtfXK2HLkWWR8dCO+rcf7OiRDRhBxAfU4=",
-        version = "v0.0.0-20221114102356-3debb6820e46",
+        sum = "h1:Ywk7n+4zm6W6T9XSyAwihBWdxXR2ALQzswQMEOglHkM=",
+        version = "v0.0.0-20221117075110-51120697d051",
     )
     go_repository(
         name = "com_github_pingcap_log",
@@ -3519,8 +3519,8 @@ def go_deps():
         name = "com_github_tikv_client_go_v2",
         build_file_proto_mode = "disable_global",
         importpath = "github.com/tikv/client-go/v2",
-        sum = "h1:nFVdyTXcQYZwQQCdSJcFI1vBFyzG1hVuZ39MAK6wqK4=",
-        version = "v2.0.3-0.20221108030801-9c0835c80eba",
+        sum = "h1:G44ccTqXvE3uZgA+8Y71RQmw/1gsst+wXtn2+qw5ykI=",
+        version = "v2.0.3-0.20221124031013-92f0a82e1a9f",
     )
     go_repository(
         name = "com_github_tikv_pd_client",

br/pkg/streamhelper/basic_lib_for_test.go

@@ -163,6 +163,10 @@ func (f *fakeStore) GetLastFlushTSOfRegion(ctx context.Context, in *logbackup.Ge
 	return resp, nil
 }
 
+func (f *fakeStore) SubscribeFlushEvent(ctx context.Context, in *logbackup.SubscribeFlushEventRequest, opts ...grpc.CallOption) (logbackup.LogBackup_SubscribeFlushEventClient, error) {
+	panic("unimplemented")
+}
+
 // RegionScan gets a list of regions, starts from the region that contains key.
 // Limit limits the maximum number of regions returned.
 func (f *fakeCluster) RegionScan(ctx context.Context, key []byte, endKey []byte, limit int) ([]streamhelper.RegionWithLeader, error) {

executor/delete.go

@@ -234,20 +234,14 @@ func (e *DeleteExec) removeRowsInTblRowMap(tblRowMap tableRowMapType) error {
 }
 
 func (e *DeleteExec) removeRow(ctx sessionctx.Context, t table.Table, h kv.Handle, data []types.Datum) error {
-	txnState, err := e.ctx.Txn(false)
-	if err != nil {
-		return err
-	}
-	memUsageOfTxnState := txnState.Size()
-	err = t.RemoveRecord(ctx, h, data)
+	err := t.RemoveRecord(ctx, h, data)
 	if err != nil {
 		return err
 	}
 	err = e.onRemoveRowForFK(ctx, t, data)
 	if err != nil {
 		return err
 	}
-	e.memTracker.Consume(int64(txnState.Size() - memUsageOfTxnState))
 	ctx.GetSessionVars().StmtCtx.AddAffectedRows(1)
 	return nil
 }

executor/executor_test.go

@@ -6237,8 +6237,7 @@ func TestSessionRootTrackerDetach(t *testing.T) {
 	tk.MustExec("create table t(a int, b int, index idx(a))")
 	tk.MustExec("create table t1(a int, c int, index idx(a))")
 	tk.MustExec("set tidb_mem_quota_query=10")
-	err := tk.ExecToErr("select /*+hash_join(t1)*/ t.a, t1.a from t use index(idx), t1 use index(idx) where t.a = t1.a")
-	require.Contains(t, err.Error(), "Out Of Memory Quota!")
+	tk.MustContainErrMsg("select /*+hash_join(t1)*/ t.a, t1.a from t use index(idx), t1 use index(idx) where t.a = t1.a", "Out Of Memory Quota!")
 	tk.MustExec("set tidb_mem_quota_query=1000")
 	rs, err := tk.Exec("select /*+hash_join(t1)*/ t.a, t1.a from t use index(idx), t1 use index(idx) where t.a = t1.a")
 	require.NoError(t, err)

executor/infoschema_reader.go

@@ -2607,7 +2607,17 @@ func (e *tidbTrxTableRetriever) retrieve(ctx context.Context, sctx sessionctx.Co
 						row = append(row, types.NewDatum(nil))
 					}
 				} else {
-					row = append(row, e.txnInfo[i].ToDatum(c.Name.O))
+					switch c.Name.O {
+					case txninfo.MemBufferBytesStr:
+						memDBFootprint := sctx.GetSessionVars().MemDBFootprint
+						var bytesConsumed int64
+						if memDBFootprint != nil {
+							bytesConsumed = memDBFootprint.BytesConsumed()
+						}
+						row = append(row, types.NewDatum(bytesConsumed))
+					default:
+						row = append(row, e.txnInfo[i].ToDatum(c.Name.O))
+					}
 				}
 			}
 			res = append(res, row)

executor/insert.go

@@ -70,7 +70,6 @@ func (e *InsertExec) exec(ctx context.Context, rows [][]types.Datum) error {
 		return err
 	}
 	setOptionForTopSQL(sessVars.StmtCtx, txn)
-	txnSize := txn.Size()
 	sessVars.StmtCtx.AddRecordRows(uint64(len(rows)))
 	// If you use the IGNORE keyword, duplicate-key error that occurs while executing the INSERT statement are ignored.
 	// For example, without IGNORE, a row that duplicates an existing UNIQUE index or PRIMARY KEY value in
@@ -113,7 +112,6 @@ func (e *InsertExec) exec(ctx context.Context, rows [][]types.Datum) error {
 			e.stats.CheckInsertTime += time.Since(start)
 		}
 	}
-	e.memTracker.Consume(int64(txn.Size() - txnSize))
 	return nil
 }
 

executor/join_test.go

@@ -2307,16 +2307,14 @@ func TestIssue18070(t *testing.T) {
 	tk.MustExec("insert into t1 values(1),(2)")
 	tk.MustExec("insert into t2 values(1),(1),(2),(2)")
 	tk.MustExec("set @@tidb_mem_quota_query=1000")
-	err := tk.QueryToErr("select /*+ inl_hash_join(t1)*/ * from t1 join t2 on t1.a = t2.a;")
-	require.True(t, strings.Contains(err.Error(), "Out Of Memory Quota!"))
+	tk.MustContainErrMsg("select /*+ inl_hash_join(t1)*/ * from t1 join t2 on t1.a = t2.a;", "Out Of Memory Quota!")
 
 	fpName := "github.com/pingcap/tidb/executor/mockIndexMergeJoinOOMPanic"
 	require.NoError(t, failpoint.Enable(fpName, `panic("ERROR 1105 (HY000): Out Of Memory Quota![conn_id=1]")`))
 	defer func() {
 		require.NoError(t, failpoint.Disable(fpName))
 	}()
-	err = tk.QueryToErr("select /*+ inl_merge_join(t1)*/ * from t1 join t2 on t1.a = t2.a;")
-	require.True(t, strings.Contains(err.Error(), "Out Of Memory Quota!"))
+	tk.MustContainErrMsg("select /*+ inl_merge_join(t1)*/ * from t1 join t2 on t1.a = t2.a;", "Out Of Memory Quota!")
 }
 
 func TestIssue18564(t *testing.T) {

executor/write.go

@@ -57,12 +57,6 @@ func updateRecord(ctx context.Context, sctx sessionctx.Context, h kv.Handle, old
 		defer span1.Finish()
 		ctx = opentracing.ContextWithSpan(ctx, span1)
 	}
-	txn, err := sctx.Txn(false)
-	if err != nil {
-		return false, err
-	}
-	memUsageOfTxnState := txn.Size()
-	defer memTracker.Consume(int64(txn.Size() - memUsageOfTxnState))
 	sc := sctx.GetSessionVars().StmtCtx
 	changed, handleChanged := false, false
 	// onUpdateSpecified is for "UPDATE SET ts_field = old_value", the
@@ -207,7 +201,7 @@ func updateRecord(ctx context.Context, sctx sessionctx.Context, h kv.Handle, old
 		}
 	} else {
 		// Update record to new value and update index.
-		if err = t.UpdateRecord(ctx, sctx, h, oldData, newData, modified); err != nil {
+		if err := t.UpdateRecord(ctx, sctx, h, oldData, newData, modified); err != nil {
 			if terr, ok := errors.Cause(err).(*terror.Error); sctx.GetSessionVars().StmtCtx.IgnoreNoPartition && ok && terr.Code() == errno.ErrNoPartitionForGivenValue {
 				return false, nil
 			}

go.mod

@@ -68,7 +68,7 @@ require (
 	github.com/pingcap/errors v0.11.5-0.20220729040631-518f63d66278
 	github.com/pingcap/failpoint v0.0.0-20220423142525-ae43b7f4e5c3
 	github.com/pingcap/fn v0.0.0-20200306044125-d5540d389059
-	github.com/pingcap/kvproto v0.0.0-20221114102356-3debb6820e46
+	github.com/pingcap/kvproto v0.0.0-20221117075110-51120697d051
 	github.com/pingcap/log v1.1.1-0.20221116035753-734d527bc87c
 	github.com/pingcap/sysutil v0.0.0-20220114020952-ea68d2dbf5b4
 	github.com/pingcap/tidb/parser v0.0.0-20211011031125-9b13dc409c5e
@@ -86,7 +86,7 @@ require (
 	github.com/stretchr/testify v1.8.0
 	github.com/tdakkota/asciicheck v0.1.1
 	github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2
-	github.com/tikv/client-go/v2 v2.0.3-0.20221108030801-9c0835c80eba
+	github.com/tikv/client-go/v2 v2.0.3-0.20221124031013-92f0a82e1a9f
 	github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07
 	github.com/timakin/bodyclose v0.0.0-20210704033933-f49887972144
 	github.com/twmb/murmur3 v1.1.3

go.sum

@@ -778,8 +778,8 @@ github.com/pingcap/goleveldb v0.0.0-20191226122134-f82aafb29989 h1:surzm05a8C9dN
 github.com/pingcap/goleveldb v0.0.0-20191226122134-f82aafb29989/go.mod h1:O17XtbryoCJhkKGbT62+L2OlrniwqiGLSqrmdHCMzZw=
 github.com/pingcap/kvproto v0.0.0-20191211054548-3c6b38ea5107/go.mod h1:WWLmULLO7l8IOcQG+t+ItJ3fEcrL5FxF0Wu+HrMy26w=
 github.com/pingcap/kvproto v0.0.0-20221026112947-f8d61344b172/go.mod h1:OYtxs0786qojVTmkVeufx93xe+jUgm56GUYRIKnmaGI=
-github.com/pingcap/kvproto v0.0.0-20221114102356-3debb6820e46 h1:HyWSOT/drBEtfXK2HLkWWR8dCO+rcf7OiRDRhBxAfU4=
-github.com/pingcap/kvproto v0.0.0-20221114102356-3debb6820e46/go.mod h1:OYtxs0786qojVTmkVeufx93xe+jUgm56GUYRIKnmaGI=
+github.com/pingcap/kvproto v0.0.0-20221117075110-51120697d051 h1:Ywk7n+4zm6W6T9XSyAwihBWdxXR2ALQzswQMEOglHkM=
+github.com/pingcap/kvproto v0.0.0-20221117075110-51120697d051/go.mod h1:OYtxs0786qojVTmkVeufx93xe+jUgm56GUYRIKnmaGI=
 github.com/pingcap/log v0.0.0-20191012051959-b742a5d432e9/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
 github.com/pingcap/log v0.0.0-20200511115504-543df19646ad/go.mod h1:4rbK1p9ILyIfb6hU7OG2CiWSqMXnp3JMbiaVJ6mvoY8=
 github.com/pingcap/log v0.0.0-20210625125904-98ed8e2eb1c7/go.mod h1:8AanEdAHATuRurdGxZXBz0At+9avep+ub7U1AGYLIMM=
@@ -928,8 +928,8 @@ github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3 h1:f+jULpR
 github.com/tenntenn/text/transform v0.0.0-20200319021203-7eef512accb3/go.mod h1:ON8b8w4BN/kE1EOhwT0o+d62W65a6aPw1nouo9LMgyY=
 github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2 h1:mbAskLJ0oJfDRtkanvQPiooDH8HvJ2FBh+iKT/OmiQQ=
 github.com/tiancaiamao/appdash v0.0.0-20181126055449-889f96f722a2/go.mod h1:2PfKggNGDuadAa0LElHrByyrz4JPZ9fFx6Gs7nx7ZZU=
-github.com/tikv/client-go/v2 v2.0.3-0.20221108030801-9c0835c80eba h1:nFVdyTXcQYZwQQCdSJcFI1vBFyzG1hVuZ39MAK6wqK4=
-github.com/tikv/client-go/v2 v2.0.3-0.20221108030801-9c0835c80eba/go.mod h1:X9s4ct/MLk1sFqe5mU79KClKegLFDTa/FCx3hzexGtk=
+github.com/tikv/client-go/v2 v2.0.3-0.20221124031013-92f0a82e1a9f h1:G44ccTqXvE3uZgA+8Y71RQmw/1gsst+wXtn2+qw5ykI=
+github.com/tikv/client-go/v2 v2.0.3-0.20221124031013-92f0a82e1a9f/go.mod h1:mQQhAIZ2uJwWXOG2UEz9s9oLGRcNKGGGtDOk4b13Bos=
 github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07 h1:ckPpxKcl75mO2N6a4cJXiZH43hvcHPpqc9dh1TmH1nc=
 github.com/tikv/pd/client v0.0.0-20221031025758-80f0d8ca4d07/go.mod h1:CipBxPfxPUME+BImx9MUYXCnAVLS3VJUr3mnSJwh40A=
 github.com/timakin/bodyclose v0.0.0-20210704033933-f49887972144 h1:kl4KhGNsJIbDHS9/4U9yQo1UcPQM0kOMJHn29EoH/Ro=

infoschema/tables_test.go

@@ -588,12 +588,12 @@ INSERT INTO ...;
 	defer func() { require.NoError(t, os.Remove(slowLogFileName)) }()
 	tk := testkit.NewTestKit(t, store)
 
-	//check schema
+	// check schema
 	tk.MustQuery(`select COUNT(*) from information_schema.columns
 WHERE table_name = 'slow_query' and column_name = '` + columnName + `'`).
 		Check(testkit.Rows("1"))
 
-	//check select
+	// check select
 	tk.MustQuery(`select ` + columnName +
 		` from information_schema.slow_query`).Check(testkit.Rows("1"))
 }
@@ -1393,16 +1393,19 @@ func TestTiDBTrx(t *testing.T) {
 	tk.MustExec("update test_tidb_trx set i = i + 1")
 	_, digest := parser.NormalizeDigest("update test_tidb_trx set i = i + 1")
 	sm := &testkit.MockSessionManager{TxnInfo: make([]*txninfo.TxnInfo, 2)}
+	memDBTracker := memory.NewTracker(memory.LabelForMemDB, -1)
+	memDBTracker.Consume(19)
+	tk.Session().GetSessionVars().MemDBFootprint = memDBTracker
 	sm.TxnInfo[0] = &txninfo.TxnInfo{
 		StartTS:          424768545227014155,
 		CurrentSQLDigest: digest.String(),
 		State:            txninfo.TxnIdle,
 		EntriesCount:     1,
-		EntriesSize:      19,
 		ConnectionID:     2,
 		Username:         "root",
 		CurrentDB:        "test",
 	}
+
 	blockTime2 := time.Date(2021, 05, 20, 13, 18, 30, 123456000, time.Local)
 	sm.TxnInfo[1] = &txninfo.TxnInfo{
 		StartTS:          425070846483628033,
@@ -1419,7 +1422,7 @@ func TestTiDBTrx(t *testing.T) {
 
 	tk.MustQuery("select * from information_schema.TIDB_TRX;").Check(testkit.Rows(
 		"424768545227014155 2021-05-07 12:56:48.001000 "+digest.String()+" update `test_tidb_trx` set `i` = `i` + ? Idle <nil> 1 19 2 root test [] ",
-		"425070846483628033 2021-05-20 21:16:35.778000 <nil> <nil> LockWaiting 2021-05-20 13:18:30.123456 0 0 10 user1 db1 [\"sql1\",\"sql2\",\""+digest.String()+"\"] "))
+		"425070846483628033 2021-05-20 21:16:35.778000 <nil> <nil> LockWaiting 2021-05-20 13:18:30.123456 0 19 10 user1 db1 [\"sql1\",\"sql2\",\""+digest.String()+"\"] "))
 
 	// Test the all_sql_digests column can be directly passed to the tidb_decode_sql_digests function.
 	require.NoError(t, failpoint.Enable("github.com/pingcap/tidb/expression/sqlDigestRetrieverSkipRetrieveGlobal", "return"))

kv/interface_mock_test.go

@@ -161,6 +161,14 @@ func (t *mockTxn) UpdateMemBufferFlags(_ []byte, _ ...FlagsOp) {
 
 }
 
+func (t *mockTxn) SetMemoryFootprintChangeHook(func(uint64)) {
+
+}
+
+func (t *mockTxn) Mem() uint64 {
+	return 0
+}
+
 // newMockTxn new a mockTxn.
 func newMockTxn() Transaction {
 	return &mockTxn{

kv/kv.go

@@ -203,6 +203,10 @@ type Transaction interface {
 	AssertionProto
 	// Size returns sum of keys and values length.
 	Size() int
+	// Mem returns the memory consumption of the transaction.
+	Mem() uint64
+	// SetMemoryFootprintChangeHook sets the hook that will be called when the memory footprint changes.
+	SetMemoryFootprintChangeHook(func(uint64))
 	// Len returns the number of entries in the DB.
 	Len() int
 	// Reset reset the Transaction to initial states.

session/session.go

@@ -93,6 +93,7 @@ import (
 	"github.com/pingcap/tidb/util/kvcache"
 	"github.com/pingcap/tidb/util/logutil"
 	"github.com/pingcap/tidb/util/logutil/consistency"
+	"github.com/pingcap/tidb/util/memory"
 	"github.com/pingcap/tidb/util/sem"
 	"github.com/pingcap/tidb/util/sli"
 	"github.com/pingcap/tidb/util/sqlexec"
@@ -569,6 +570,7 @@ func (s *session) FieldList(tableName string) ([]*ast.ResultField, error) {
 	return fields, nil
 }
 
+// TxnInfo returns a pointer to a *copy* of the internal TxnInfo, thus is *read only*
 func (s *session) TxnInfo() *txninfo.TxnInfo {
 	s.txn.mu.RLock()
 	// Copy on read to get a snapshot, this API shouldn't be frequently called.
@@ -2506,6 +2508,7 @@ func (s *session) Txn(active bool) (kv.Transaction, error) {
 		return &s.txn, nil
 	}
 	_, err := sessiontxn.GetTxnManager(s).ActivateTxn()
+	s.SetMemoryFootprintChangeHook()
 	return &s.txn, err
 }
 
@@ -3659,6 +3662,20 @@ func (s *session) GetStmtStats() *stmtstats.StatementStats {
 	return s.stmtStats
 }
 
+// SetMemoryFootprintChangeHook sets the hook that is called when the memdb changes its size.
+// Call this after s.txn becomes valid, since TxnInfo is initialized when the txn becomes valid.
+func (s *session) SetMemoryFootprintChangeHook() {
+	hook := func(mem uint64) {
+		if s.sessionVars.MemDBFootprint == nil {
+			tracker := memory.NewTracker(memory.LabelForMemDB, -1)
+			tracker.AttachTo(s.sessionVars.MemTracker)
+			s.sessionVars.MemDBFootprint = tracker
+		}
+		s.sessionVars.MemDBFootprint.ReplaceBytesUsed(int64(mem))
+	}
+	s.txn.SetMemoryFootprintChangeHook(hook)
+}
+
 // EncodeSessionStates implements SessionStatesHandler.EncodeSessionStates interface.
 func (s *session) EncodeSessionStates(ctx context.Context, sctx sessionctx.Context, sessionStates *sessionstates.SessionStates) error {
 	// Transaction status is hard to encode, so we do not support it.

session/txn.go

@@ -151,16 +151,14 @@ func (txn *LazyTxn) cleanupStmtBuf() {
 	txn.mu.Lock()
 	defer txn.mu.Unlock()
 	txn.mu.TxnInfo.EntriesCount = uint64(txn.Transaction.Len())
-	txn.mu.TxnInfo.EntriesSize = uint64(txn.Transaction.Size())
 }
 
 // resetTxnInfo resets the transaction info.
 // Note: call it under lock!
 func (txn *LazyTxn) resetTxnInfo(
 	startTS uint64,
 	state txninfo.TxnRunningState,
-	entriesCount,
-	entriesSize uint64,
+	entriesCount uint64,
 	currentSQLDigest string,
 	allSQLDigests []string,
 ) {
@@ -178,7 +176,7 @@ func (txn *LazyTxn) resetTxnInfo(
 	txninfo.TxnStatusEnteringCounter(state).Inc()
 	txn.mu.TxnInfo.LastStateChangeTime = time.Now()
 	txn.mu.TxnInfo.EntriesCount = entriesCount
-	txn.mu.TxnInfo.EntriesSize = entriesSize
+
 	txn.mu.TxnInfo.CurrentSQLDigest = currentSQLDigest
 	txn.mu.TxnInfo.AllSQLDigests = allSQLDigests
 }
@@ -191,6 +189,22 @@ func (txn *LazyTxn) Size() int {
 	return txn.Transaction.Size()
 }
 
+// Mem implements the MemBuffer interface.
+func (txn *LazyTxn) Mem() uint64 {
+	if txn.Transaction == nil {
+		return 0
+	}
+	return txn.Transaction.Mem()
+}
+
+// SetMemoryFootprintChangeHook sets the hook to be called when the memory footprint of this transaction changes.
+func (txn *LazyTxn) SetMemoryFootprintChangeHook(hook func(uint64)) {
+	if txn.Transaction == nil {
+		return
+	}
+	txn.Transaction.SetMemoryFootprintChangeHook(hook)
+}
+
 // Valid implements the kv.Transaction interface.
 func (txn *LazyTxn) Valid() bool {
 	return txn.Transaction != nil && txn.Transaction.Valid()
@@ -275,7 +289,6 @@ func (txn *LazyTxn) changePendingToValid(ctx context.Context) error {
 		t.StartTS(),
 		txninfo.TxnIdle,
 		uint64(txn.Transaction.Len()),
-		uint64(txn.Transaction.Size()),
 		txn.mu.TxnInfo.CurrentSQLDigest,
 		txn.mu.TxnInfo.AllSQLDigests)
 
@@ -433,7 +446,6 @@ func (txn *LazyTxn) LockKeys(ctx context.Context, lockCtx *kv.LockCtx, keys ...k
 	txn.updateState(originState)
 	txn.mu.TxnInfo.BlockStartTime.Valid = false
 	txn.mu.TxnInfo.EntriesCount = uint64(txn.Transaction.Len())
-	txn.mu.TxnInfo.EntriesSize = uint64(txn.Transaction.Size())
 	return err
 }
 

session/txninfo/txn_info.go

@@ -161,8 +161,6 @@ type TxnInfo struct {
 	}
 	// How many entries are in MemDB
 	EntriesCount uint64
-	// MemDB used memory
-	EntriesSize uint64
 
 	// The following fields will be filled in `session` instead of `LazyTxn`
 
@@ -208,9 +206,6 @@ var columnValueGetterMap = map[string]func(*TxnInfo) types.Datum{
 	MemBufferKeysStr: func(info *TxnInfo) types.Datum {
 		return types.NewDatum(info.EntriesCount)
 	},
-	MemBufferBytesStr: func(info *TxnInfo) types.Datum {
-		return types.NewDatum(info.EntriesSize)
-	},
 	SessionIDStr: func(info *TxnInfo) types.Datum {
 		return types.NewDatum(info.ConnectionID)
 	},

sessionctx/variable/session.go

@@ -1290,8 +1290,10 @@ type SessionVars struct {
 	HookContext
 
 	// MemTracker indicates the memory tracker of current session.
-	MemTracker  *memory.Tracker
-	DiskTracker *memory.Tracker
+	MemTracker *memory.Tracker
+	// MemDBDBFootprint tracks the memory footprint of memdb, and is attached to `MemTracker`
+	MemDBFootprint *memory.Tracker
+	DiskTracker    *memory.Tracker
 
 	// OptPrefixIndexSingleScan indicates whether to do some optimizations to avoid double scan for prefix index.
 	// When set to true, `col is (not) null`(`col` is index prefix column) is regarded as index filter rather than table filter.