diff --git a/pkg/ddl/ddl_worker.go b/pkg/ddl/ddl_worker.go
index a98513c85d626..3b59093359124 100644
--- a/pkg/ddl/ddl_worker.go
+++ b/pkg/ddl/ddl_worker.go
@@ -926,23 +926,6 @@ func writeBinlog(binlogCli *pumpcli.PumpsClient, txn kv.Transaction, job *model.
 	}
 }
 
-// waitDependencyJobFinished waits for the dependency-job to be finished.
-// If the dependency job isn't finished yet, we'd better wait a moment.
-func (w *worker) waitDependencyJobFinished(job *model.Job, cnt *int) {
-	if job.DependencyID != noneDependencyJob {
-		intervalCnt := int(3 * time.Second / waitDependencyJobInterval)
-		if *cnt%intervalCnt == 0 {
-			w.jobLogger(job).Info("DDL job need to wait dependent job, sleeps a while, then retries it.",
-				zap.Int64("dependentJobID", job.DependencyID),
-				zap.Duration("waitTime", waitDependencyJobInterval))
-		}
-		time.Sleep(waitDependencyJobInterval)
-		*cnt++
-	} else {
-		*cnt = 0
-	}
-}
-
 func chooseLeaseTime(t, max time.Duration) time.Duration {
 	if t == 0 || t > max {
 		return max
diff --git a/pkg/domain/plan_replayer.go b/pkg/domain/plan_replayer.go
index fddee4868ae30..4980395a80126 100644
--- a/pkg/domain/plan_replayer.go
+++ b/pkg/domain/plan_replayer.go
@@ -52,10 +52,6 @@ type dumpFileGcChecker struct {
 	planReplayerTaskStatus *planReplayerDumpTaskStatus
 }
 
-func parseType(s string) string {
-	return strings.Split(s, "_")[0]
-}
-
 func parseTime(s string) (time.Time, error) {
 	startIdx := strings.LastIndex(s, "_")
 	if startIdx == -1 {
diff --git a/pkg/executor/internal/calibrateresource/calibrate_resource.go b/pkg/executor/internal/calibrateresource/calibrate_resource.go
index 0d3a34c60f0ee..a4dedeba6f44b 100644
--- a/pkg/executor/internal/calibrateresource/calibrate_resource.go
+++ b/pkg/executor/internal/calibrateresource/calibrate_resource.go
@@ -595,18 +595,6 @@ func getComponentCPUUsagePerSec(ctx context.Context, sctx sessionctx.Context, ex
 	return getValuesFromMetrics(ctx, sctx, exec, query)
 }
 
-func getNumberFromMetrics(ctx context.Context, exec sqlexec.RestrictedSQLExecutor, query, metrics string) (float64, error) {
-	rows, _, err := exec.ExecRestrictedSQL(ctx, []sqlexec.OptionFuncAlias{sqlexec.ExecOptionUseCurSession}, query)
-	if err != nil {
-		return 0.0, errors.Trace(err)
-	}
-	if len(rows) == 0 {
-		return 0.0, errors.Errorf("metrics '%s' is empty", metrics)
-	}
-
-	return rows[0].GetFloat64(0), nil
-}
-
 func getValuesFromMetrics(ctx context.Context, sctx sessionctx.Context, exec sqlexec.RestrictedSQLExecutor, query string) (*timeSeriesValues, error) {
 	rows, _, err := exec.ExecRestrictedSQL(ctx, []sqlexec.OptionFuncAlias{sqlexec.ExecOptionUseCurSession}, query)
 	if err != nil {
diff --git a/pkg/planner/core/planbuilder.go b/pkg/planner/core/planbuilder.go
index ee2f416adc92e..dd819dc204238 100644
--- a/pkg/planner/core/planbuilder.go
+++ b/pkg/planner/core/planbuilder.go
@@ -1300,17 +1300,6 @@ func removeGlobalIndexPaths(paths []*util.AccessPath) []*util.AccessPath {
 	return paths[:i]
 }
 
-func removeTiflashDuringStaleRead(paths []*util.AccessPath) []*util.AccessPath {
-	n := 0
-	for _, path := range paths {
-		if path.StoreType != kv.TiFlash {
-			paths[n] = path
-			n++
-		}
-	}
-	return paths[:n]
-}
-
 func (b *PlanBuilder) buildSelectLock(src LogicalPlan, lock *ast.SelectLockInfo) (*LogicalLock, error) {
 	var tblID2PhysTblIDCol map[int64]*expression.Column
 	if len(b.partitionedTable) > 0 {
diff --git a/pkg/planner/core/scalar_subq_expression.go b/pkg/planner/core/scalar_subq_expression.go
index e677d7e260066..d51617aa6669b 100644
--- a/pkg/planner/core/scalar_subq_expression.go
+++ b/pkg/planner/core/scalar_subq_expression.go
@@ -184,12 +184,12 @@ func (*ScalarSubQueryExpr) ConstLevel() expression.ConstLevel {
 }
 
 // Decorrelate implements the Expression interface.
-func (s *ScalarSubQueryExpr) Decorrelate(_ *expression.Schema) expression.Expression {
+func (s *ScalarSubQueryExpr) Decorrelate(*expression.Schema) expression.Expression {
 	return s
 }
 
 // resolveIndices implements the Expression interface.
-func (*ScalarSubQueryExpr) resolveIndices(_ *expression.Schema) error {
+func (*ScalarSubQueryExpr) resolveIndices(*expression.Schema) error {
 	return nil
 }