diff --git a/pkg/sql/sqlbase/structured.pb.go b/pkg/sql/sqlbase/structured.pb.go
index b2de58d3460d..d2ae66d7d785 100644
--- a/pkg/sql/sqlbase/structured.pb.go
+++ b/pkg/sql/sqlbase/structured.pb.go
@@ -73,7 +73,7 @@ func (x *ConstraintValidity) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (ConstraintValidity) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{0}
 }
 
 type ForeignKeyReference_Action int32
@@ -118,7 +118,7 @@ func (x *ForeignKeyReference_Action) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (ForeignKeyReference_Action) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{0, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{0, 0}
 }
 
 // Match is the algorithm used to compare composite keys.
@@ -158,7 +158,7 @@ func (x *ForeignKeyReference_Match) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (ForeignKeyReference_Match) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{0, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{0, 1}
 }
 
 // The direction of a column in the index.
@@ -195,7 +195,7 @@ func (x *IndexDescriptor_Direction) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (IndexDescriptor_Direction) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{6, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{6, 0}
 }
 
 // The type of the index.
@@ -232,7 +232,7 @@ func (x *IndexDescriptor_Type) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (IndexDescriptor_Type) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{6, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{6, 1}
 }
 
 type ConstraintToUpdate_ConstraintType int32
@@ -275,7 +275,7 @@ func (x *ConstraintToUpdate_ConstraintType) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (ConstraintToUpdate_ConstraintType) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{7, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{7, 0}
 }
 
 // A descriptor within a mutation is unavailable for reads, writes
@@ -340,7 +340,7 @@ func (x *DescriptorMutation_State) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (DescriptorMutation_State) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{8, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{8, 0}
 }
 
 // Direction of mutation.
@@ -383,7 +383,7 @@ func (x *DescriptorMutation_Direction) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (DescriptorMutation_Direction) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{8, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{8, 1}
 }
 
 // State is set if this TableDescriptor is in the process of being added or deleted.
@@ -434,7 +434,7 @@ func (x *TableDescriptor_State) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (TableDescriptor_State) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 0}
 }
 
 // AuditMode indicates which auditing actions to take when this table is used.
@@ -471,7 +471,7 @@ func (x *TableDescriptor_AuditMode) UnmarshalJSON(data []byte) error {
 	return nil
 }
 func (TableDescriptor_AuditMode) EnumDescriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 1}
 }
 
 type ForeignKeyReference struct {
@@ -493,7 +493,7 @@ func (m *ForeignKeyReference) Reset()         { *m = ForeignKeyReference{} }
 func (m *ForeignKeyReference) String() string { return proto.CompactTextString(m) }
 func (*ForeignKeyReference) ProtoMessage()    {}
 func (*ForeignKeyReference) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{0}
 }
 func (m *ForeignKeyReference) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -561,7 +561,7 @@ func (m *ForeignKeyConstraint) Reset()         { *m = ForeignKeyConstraint{} }
 func (m *ForeignKeyConstraint) String() string { return proto.CompactTextString(m) }
 func (*ForeignKeyConstraint) ProtoMessage()    {}
 func (*ForeignKeyConstraint) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{1}
 }
 func (m *ForeignKeyConstraint) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -608,7 +608,7 @@ func (m *ColumnDescriptor) Reset()         { *m = ColumnDescriptor{} }
 func (m *ColumnDescriptor) String() string { return proto.CompactTextString(m) }
 func (*ColumnDescriptor) ProtoMessage()    {}
 func (*ColumnDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{2}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{2}
 }
 func (m *ColumnDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -664,7 +664,7 @@ func (m *ColumnFamilyDescriptor) Reset()         { *m = ColumnFamilyDescriptor{}
 func (m *ColumnFamilyDescriptor) String() string { return proto.CompactTextString(m) }
 func (*ColumnFamilyDescriptor) ProtoMessage()    {}
 func (*ColumnFamilyDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{3}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{3}
 }
 func (m *ColumnFamilyDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -710,7 +710,7 @@ func (m *InterleaveDescriptor) Reset()         { *m = InterleaveDescriptor{} }
 func (m *InterleaveDescriptor) String() string { return proto.CompactTextString(m) }
 func (*InterleaveDescriptor) ProtoMessage()    {}
 func (*InterleaveDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{4}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{4}
 }
 func (m *InterleaveDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -754,7 +754,7 @@ func (m *InterleaveDescriptor_Ancestor) Reset()         { *m = InterleaveDescrip
 func (m *InterleaveDescriptor_Ancestor) String() string { return proto.CompactTextString(m) }
 func (*InterleaveDescriptor_Ancestor) ProtoMessage()    {}
 func (*InterleaveDescriptor_Ancestor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{4, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{4, 0}
 }
 func (m *InterleaveDescriptor_Ancestor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -799,7 +799,7 @@ func (m *PartitioningDescriptor) Reset()         { *m = PartitioningDescriptor{}
 func (m *PartitioningDescriptor) String() string { return proto.CompactTextString(m) }
 func (*PartitioningDescriptor) ProtoMessage()    {}
 func (*PartitioningDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{5}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{5}
 }
 func (m *PartitioningDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -842,7 +842,7 @@ func (m *PartitioningDescriptor_List) Reset()         { *m = PartitioningDescrip
 func (m *PartitioningDescriptor_List) String() string { return proto.CompactTextString(m) }
 func (*PartitioningDescriptor_List) ProtoMessage()    {}
 func (*PartitioningDescriptor_List) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{5, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{5, 0}
 }
 func (m *PartitioningDescriptor_List) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -887,7 +887,7 @@ func (m *PartitioningDescriptor_Range) Reset()         { *m = PartitioningDescri
 func (m *PartitioningDescriptor_Range) String() string { return proto.CompactTextString(m) }
 func (*PartitioningDescriptor_Range) ProtoMessage()    {}
 func (*PartitioningDescriptor_Range) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{5, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{5, 1}
 }
 func (m *PartitioningDescriptor_Range) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1023,7 +1023,7 @@ func (m *IndexDescriptor) Reset()         { *m = IndexDescriptor{} }
 func (m *IndexDescriptor) String() string { return proto.CompactTextString(m) }
 func (*IndexDescriptor) ProtoMessage()    {}
 func (*IndexDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{6}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{6}
 }
 func (m *IndexDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1074,7 +1074,7 @@ func (m *ConstraintToUpdate) Reset()         { *m = ConstraintToUpdate{} }
 func (m *ConstraintToUpdate) String() string { return proto.CompactTextString(m) }
 func (*ConstraintToUpdate) ProtoMessage()    {}
 func (*ConstraintToUpdate) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{7}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{7}
 }
 func (m *ConstraintToUpdate) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1128,7 +1128,7 @@ func (m *DescriptorMutation) Reset()         { *m = DescriptorMutation{} }
 func (m *DescriptorMutation) String() string { return proto.CompactTextString(m) }
 func (*DescriptorMutation) ProtoMessage()    {}
 func (*DescriptorMutation) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{8}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{8}
 }
 func (m *DescriptorMutation) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1440,7 +1440,7 @@ func (m *TableDescriptor) Reset()         { *m = TableDescriptor{} }
 func (m *TableDescriptor) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor) ProtoMessage()    {}
 func (*TableDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9}
 }
 func (m *TableDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1732,7 +1732,7 @@ func (m *TableDescriptor_SchemaChangeLease) Reset()         { *m = TableDescript
 func (m *TableDescriptor_SchemaChangeLease) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_SchemaChangeLease) ProtoMessage()    {}
 func (*TableDescriptor_SchemaChangeLease) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 0}
 }
 func (m *TableDescriptor_SchemaChangeLease) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1770,7 +1770,7 @@ func (m *TableDescriptor_CheckConstraint) Reset()         { *m = TableDescriptor
 func (m *TableDescriptor_CheckConstraint) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_CheckConstraint) ProtoMessage()    {}
 func (*TableDescriptor_CheckConstraint) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 1}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 1}
 }
 func (m *TableDescriptor_CheckConstraint) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1873,7 +1873,7 @@ func (m *TableDescriptor_NameInfo) Reset()         { *m = TableDescriptor_NameIn
 func (m *TableDescriptor_NameInfo) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_NameInfo) ProtoMessage()    {}
 func (*TableDescriptor_NameInfo) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 2}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 2}
 }
 func (m *TableDescriptor_NameInfo) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1913,7 +1913,7 @@ func (m *TableDescriptor_Reference) Reset()         { *m = TableDescriptor_Refer
 func (m *TableDescriptor_Reference) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_Reference) ProtoMessage()    {}
 func (*TableDescriptor_Reference) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 3}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 3}
 }
 func (m *TableDescriptor_Reference) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1950,7 +1950,7 @@ func (m *TableDescriptor_MutationJob) Reset()         { *m = TableDescriptor_Mut
 func (m *TableDescriptor_MutationJob) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_MutationJob) ProtoMessage()    {}
 func (*TableDescriptor_MutationJob) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 4}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 4}
 }
 func (m *TableDescriptor_MutationJob) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -1993,7 +1993,7 @@ func (m *TableDescriptor_SequenceOpts) Reset()         { *m = TableDescriptor_Se
 func (m *TableDescriptor_SequenceOpts) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_SequenceOpts) ProtoMessage()    {}
 func (*TableDescriptor_SequenceOpts) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 5}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 5}
 }
 func (m *TableDescriptor_SequenceOpts) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -2033,7 +2033,7 @@ func (m *TableDescriptor_SequenceOpts_SequenceOwner) String() string {
 }
 func (*TableDescriptor_SequenceOpts_SequenceOwner) ProtoMessage() {}
 func (*TableDescriptor_SequenceOpts_SequenceOwner) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 5, 0}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 5, 0}
 }
 func (m *TableDescriptor_SequenceOpts_SequenceOwner) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -2059,7 +2059,13 @@ func (m *TableDescriptor_SequenceOpts_SequenceOwner) XXX_DiscardUnknown() {
 var xxx_messageInfo_TableDescriptor_SequenceOpts_SequenceOwner proto.InternalMessageInfo
 
 type TableDescriptor_Replacement struct {
-	ID   ID            `protobuf:"varint,1,opt,name=id,casttype=ID" json:"id"`
+	ID ID `protobuf:"varint,1,opt,name=id,casttype=ID" json:"id"`
+	// Time is just used for debugging purposes. It is not used in business
+	// logic. It is an HLC rather than just wall time only for historical
+	// reasons. Prior to 20.1 it was populated with the commit timestamp of the
+	// transaction which created this replacement. In 20.1 and after it is
+	// populated with the read timestamp at which the descriptor being
+	// replaced was read.
 	Time hlc.Timestamp `protobuf:"bytes,2,opt,name=time" json:"time"`
 }
 
@@ -2067,7 +2073,7 @@ func (m *TableDescriptor_Replacement) Reset()         { *m = TableDescriptor_Rep
 func (m *TableDescriptor_Replacement) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_Replacement) ProtoMessage()    {}
 func (*TableDescriptor_Replacement) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 6}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 6}
 }
 func (m *TableDescriptor_Replacement) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -2104,7 +2110,7 @@ func (m *TableDescriptor_GCDescriptorMutation) Reset()         { *m = TableDescr
 func (m *TableDescriptor_GCDescriptorMutation) String() string { return proto.CompactTextString(m) }
 func (*TableDescriptor_GCDescriptorMutation) ProtoMessage()    {}
 func (*TableDescriptor_GCDescriptorMutation) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{9, 7}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{9, 7}
 }
 func (m *TableDescriptor_GCDescriptorMutation) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -2143,7 +2149,7 @@ func (m *DatabaseDescriptor) Reset()         { *m = DatabaseDescriptor{} }
 func (m *DatabaseDescriptor) String() string { return proto.CompactTextString(m) }
 func (*DatabaseDescriptor) ProtoMessage()    {}
 func (*DatabaseDescriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{10}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{10}
 }
 func (m *DatabaseDescriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -2201,7 +2207,7 @@ func (m *Descriptor) Reset()         { *m = Descriptor{} }
 func (m *Descriptor) String() string { return proto.CompactTextString(m) }
 func (*Descriptor) ProtoMessage()    {}
 func (*Descriptor) Descriptor() ([]byte, []int) {
-	return fileDescriptor_structured_50daf820b4f615f7, []int{11}
+	return fileDescriptor_structured_d9b38487027f89a8, []int{11}
 }
 func (m *Descriptor) XXX_Unmarshal(b []byte) error {
 	return m.Unmarshal(b)
@@ -11156,10 +11162,10 @@ var (
 )
 
 func init() {
-	proto.RegisterFile("sql/sqlbase/structured.proto", fileDescriptor_structured_50daf820b4f615f7)
+	proto.RegisterFile("sql/sqlbase/structured.proto", fileDescriptor_structured_d9b38487027f89a8)
 }
 
-var fileDescriptor_structured_50daf820b4f615f7 = []byte{
+var fileDescriptor_structured_d9b38487027f89a8 = []byte{
 	// 3473 bytes of a gzipped FileDescriptorProto
 	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xb4, 0x5a, 0xcb, 0x6f, 0x23, 0x47,
 	0x7a, 0x57, 0xf3, 0xcd, 0x8f, 0xaf, 0x66, 0x69, 0x66, 0x4c, 0xcb, 0x5e, 0x91, 0xa2, 0x3d, 0xb6,
diff --git a/pkg/sql/sqlbase/structured.proto b/pkg/sql/sqlbase/structured.proto
index beb3e9a27ed7..3dca04a2b4e0 100644
--- a/pkg/sql/sqlbase/structured.proto
+++ b/pkg/sql/sqlbase/structured.proto
@@ -799,6 +799,12 @@ message TableDescriptor {
   message Replacement {
     option (gogoproto.equal) = true;
     optional uint32 id = 1 [(gogoproto.nullable) = false, (gogoproto.customname) = "ID", (gogoproto.casttype) = "ID"];
+    // Time is just used for debugging purposes. It is not used in business
+    // logic. It is an HLC rather than just wall time only for historical
+    // reasons. Prior to 20.1 it was populated with the commit timestamp of the
+    // transaction which created this replacement. In 20.1 and after it is
+    // populated with the read timestamp at which the descriptor being
+    // replaced was read.
     optional util.hlc.Timestamp time = 2 [(gogoproto.nullable) = false];
   }
 
diff --git a/pkg/sql/truncate.go b/pkg/sql/truncate.go
index 0f8fa49b1488..6f720d02f2c3 100644
--- a/pkg/sql/truncate.go
+++ b/pkg/sql/truncate.go
@@ -190,7 +190,10 @@ func (p *planner) truncateTable(
 	tableDesc.DropJobID = dropJobID
 	newTableDesc := sqlbase.NewMutableCreatedTableDescriptor(tableDesc.TableDescriptor)
 	newTableDesc.ReplacementOf = sqlbase.TableDescriptor_Replacement{
-		ID: id, Time: p.txn.CommitTimestamp(),
+		ID: id,
+		// NB: Time is just used for debugging purposes. See the comment on the
+		// field for more details.
+		Time: p.txn.ReadTimestamp(),
 	}
 	newTableDesc.SetID(0)
 	newTableDesc.Version = 1