diff --git a/executor/stale_txn_test.go b/executor/stale_txn_test.go
index ce5202ae58a75..493bda06c5de2 100644
--- a/executor/stale_txn_test.go
+++ b/executor/stale_txn_test.go
@@ -312,7 +312,7 @@ func (s *testStaleTxnSerialSuite) TestTimeBoundedStalenessTxn(c *C) {
 		if testcase.useSafeTS {
 			c.Assert(tk.Se.GetSessionVars().TxnCtx.StartTS, Equals, testcase.injectSafeTS)
 		} else {
-			c.Assert(oracle.CompareTS(tk.Se.GetSessionVars().TxnCtx.StartTS, testcase.injectSafeTS), Equals, 1)
+			c.Assert(tk.Se.GetSessionVars().TxnCtx.StartTS, Greater, testcase.injectSafeTS)
 		}
 		tk.MustExec("commit")
 		failpoint.Disable("github.com/pingcap/tidb/store/tikv/injectSafeTS")
diff --git a/store/tikv/oracle/oracle.go b/store/tikv/oracle/oracle.go
index 0a6865cf59039..daf00c66814ca 100644
--- a/store/tikv/oracle/oracle.go
+++ b/store/tikv/oracle/oracle.go
@@ -148,25 +148,6 @@ func GoTimeToTS(t time.Time) uint64 {
 	return uint64(ts)
 }
 
-// CompareTS is used to compare two timestamps.
-// If tsoOne > tsoTwo, returns 1.
-// If tsoOne = tsoTwo, returns 0.
-// If tsoOne < tsoTwo, returns -1.
-func CompareTS(tsoOne, tsoTwo uint64) int {
-	tsOnePhy := ExtractPhysical(tsoOne)
-	tsOneLog := ExtractLogical(tsoOne)
-	tsTwoPhy := ExtractPhysical(tsoTwo)
-	tsTwoLog := ExtractLogical(tsoTwo)
-
-	if tsOnePhy > tsTwoPhy || (tsOnePhy == tsTwoPhy && tsOneLog > tsTwoLog) {
-		return 1
-	}
-	if tsOnePhy == tsTwoPhy && tsOneLog == tsTwoLog {
-		return 0
-	}
-	return -1
-}
-
 // GoTimeToLowerLimitStartTS returns the min start_ts of the uncommitted transaction.
 // maxTxnTimeUse means the max time a Txn May use (in ms) from its begin to commit.
 func GoTimeToLowerLimitStartTS(now time.Time, maxTxnTimeUse int64) uint64 {
diff --git a/store/tikv/txn.go b/store/tikv/txn.go
index aafaa2b323d24..beeeafe66a063 100644
--- a/store/tikv/txn.go
+++ b/store/tikv/txn.go
@@ -119,7 +119,7 @@ func extractStartTs(store *KVStore, options kv.TransactionOption) (uint64, error
 		startTs = *options.MinStartTS
 		// If the safeTS is larger than the minStartTS, we will use safeTS as StartTS, otherwise we will use
 		// minStartTS directly.
-		if oracle.CompareTS(startTs, safeTS) < 0 {
+		if startTs < safeTS {
 			startTs = safeTS
 		}
 	} else if options.MaxPrevSec != nil {