diff --git a/frame.go b/frame.go
index d52cb8fe1..1d6867746 100644
--- a/frame.go
+++ b/frame.go
@@ -113,8 +113,8 @@ func (f *Frame) RowAttrStore() *AttrStore { return f.rowAttrStore }
 
 // MaxSlice returns the max slice in the frame.
 func (f *Frame) MaxSlice() uint64 {
-	f.mu.Lock()
-	defer f.mu.Unlock()
+	f.mu.RLock()
+	defer f.mu.RUnlock()
 
 	var max uint64
 	for _, view := range f.views {
@@ -129,8 +129,8 @@ func (f *Frame) MaxSlice() uint64 {
 
 // MaxInverseSlice returns the max inverse slice in the frame.
 func (f *Frame) MaxInverseSlice() uint64 {
-	f.mu.Lock()
-	defer f.mu.Unlock()
+	f.mu.RLock()
+	defer f.mu.RUnlock()
 
 	view := f.views[ViewInverse]
 	if view == nil {
diff --git a/index.go b/index.go
index 93100e1da..256c44184 100644
--- a/index.go
+++ b/index.go
@@ -276,8 +276,8 @@ func (i *Index) MaxSlice() uint64 {
 	if i == nil {
 		return 0
 	}
-	i.mu.Lock()
-	defer i.mu.Unlock()
+	i.mu.RLock()
+	defer i.mu.RUnlock()
 
 	max := i.remoteMaxSlice
 	for _, f := range i.frames {
@@ -302,8 +302,8 @@ func (i *Index) MaxInverseSlice() uint64 {
 	if i == nil {
 		return 0
 	}
-	i.mu.Lock()
-	defer i.mu.Unlock()
+	i.mu.RLock()
+	defer i.mu.RUnlock()
 
 	max := i.remoteMaxInverseSlice
 	for _, f := range i.frames {
@@ -323,8 +323,8 @@ func (i *Index) SetRemoteMaxInverseSlice(v uint64) {
 
 // TimeQuantum returns the default time quantum for the index.
 func (i *Index) TimeQuantum() TimeQuantum {
-	i.mu.Lock()
-	defer i.mu.Unlock()
+	i.mu.RLock()
+	defer i.mu.RUnlock()
 	return i.timeQuantum
 }
 
@@ -380,8 +380,8 @@ func (i *Index) inputDefinition(name string) *InputDefinition { return i.inputDe
 
 // Frames returns a list of all frames in the index.
 func (i *Index) Frames() []*Frame {
-	i.mu.Lock()
-	defer i.mu.Unlock()
+	i.mu.RLock()
+	defer i.mu.RUnlock()
 
 	a := make([]*Frame, 0, len(i.frames))
 	for _, f := range i.frames {
diff --git a/view.go b/view.go
index 3f5a61437..e9bbb9c5f 100644
--- a/view.go
+++ b/view.go
@@ -174,8 +174,8 @@ func (v *View) Close() error {
 
 // MaxSlice returns the max slice in the view.
 func (v *View) MaxSlice() uint64 {
-	v.mu.Lock()
-	defer v.mu.Unlock()
+	v.mu.RLock()
+	defer v.mu.RUnlock()
 
 	var max uint64
 	for slice := range v.fragments {