*: improve log about stale-read query

pkg/executor/executor.go

@@ -1993,6 +1993,7 @@ func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
 	sc.TaskID = stmtctx.AllocateTaskID()
 	sc.CTEStorageMap = map[int]*CTEStorages{}
 	sc.IsStaleness = false
+	sc.StaleReadTs = 0
 	sc.LockTableIDs = make(map[int64]struct{})
 	sc.EnableOptimizeTrace = false
 	sc.OptimizeTracer = nil

pkg/planner/core/preprocess.go

@@ -1748,6 +1748,7 @@ func (p *preprocessor) updateStateFromStaleReadProcessor() error {
 		if p.flag&initTxnContextProvider != 0 {
 			p.sctx.GetSessionVars().StmtCtx.IsStaleness = true
 			if !p.sctx.GetSessionVars().InTxn() {
+				p.sctx.GetSessionVars().StmtCtx.StaleReadTs = p.LastSnapshotTS
 				txnManager := sessiontxn.GetTxnManager(p.sctx)
 				newTxnRequest := &sessiontxn.EnterNewTxnRequest{
 					Type:     sessiontxn.EnterNewTxnWithReplaceProvider,

pkg/server/conn.go

@@ -1139,17 +1139,23 @@ func (cc *clientConn) Run(ctx context.Context) {
 			if storeerr.ErrLockAcquireFailAndNoWaitSet.Equal(err) {
 				logutil.Logger(ctx).Debug("Expected error for FOR UPDATE NOWAIT", zap.Error(err))
 			} else {
-				var startTS uint64
-				if ctx := cc.getCtx(); ctx != nil && ctx.GetSessionVars() != nil && ctx.GetSessionVars().TxnCtx != nil {
-					startTS = ctx.GetSessionVars().TxnCtx.StartTS
+				var timestamp uint64
+				if ctx := cc.getCtx(); ctx != nil && ctx.GetSessionVars() != nil {
+					if ctx.GetSessionVars().TxnCtx != nil {
+						timestamp = ctx.GetSessionVars().TxnCtx.StartTS
+					}
+					if timestamp == 0 && ctx.GetSessionVars().StmtCtx != nil && ctx.GetSessionVars().StmtCtx.StaleReadTs > 0 {
+						// for state-read query.
+						timestamp = ctx.GetSessionVars().StmtCtx.StaleReadTs
+					}
 				}
 				logutil.Logger(ctx).Info("command dispatched failed",
 					zap.String("connInfo", cc.String()),
 					zap.String("command", mysql.Command2Str[data[0]]),
 					zap.String("status", cc.SessionStatusToString()),
 					zap.Stringer("sql", getLastStmtInConn{cc}),
 					zap.String("txn_mode", txnMode),
-					zap.Uint64("timestamp", startTS),
+					zap.Uint64("timestamp", timestamp),
 					zap.String("err", errStrForLog(err, cc.ctx.GetSessionVars().EnableRedactLog)),
 				)
 			}

pkg/session/txnmanager.go

@@ -333,6 +333,7 @@ func (m *txnManager) newProviderWithRequest(r *sessiontxn.EnterNewTxnRequest) (s
 	}
 
 	if r.StaleReadTS > 0 {
+		m.sctx.GetSessionVars().StmtCtx.StaleReadTs = r.StaleReadTS
 		return staleread.NewStalenessTxnContextProvider(m.sctx, r.StaleReadTS, nil), nil
 	}
 

pkg/sessionctx/stmtctx/stmtctx.go

@@ -219,6 +219,7 @@ type StatementContext struct {
 	// or is affected by the tidb_read_staleness session variable, then the statement will be makred as isStaleness
 	// in stmtCtx
 	IsStaleness     bool
+	StaleReadTs     uint64
 	InRestrictedSQL bool
 	ViewDepth       int32
 	// mu struct holds variables that change during execution.