diff --git a/tsdb/tsm1/engine_measurement_schema.go b/tsdb/tsm1/engine_measurement_schema.go
index 55724278ab..103adb08b9 100644
--- a/tsdb/tsm1/engine_measurement_schema.go
+++ b/tsdb/tsm1/engine_measurement_schema.go
@@ -348,6 +348,7 @@ func (e *Engine) fieldsPredicate(ctx context.Context, orgID influxdb.ID, bucketI
 
 	mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 	tsmKeyPrefix := mt.AppendHashKey(orgBucketEsc)
+	tsmKeyPrefix = append(tsmKeyPrefix, ',')
 
 	var canceled bool
 
@@ -453,6 +454,7 @@ func (e *Engine) fieldsNoPredicate(ctx context.Context, orgID influxdb.ID, bucke
 
 	mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 	tsmKeyPrefix := mt.AppendHashKey(orgBucketEsc)
+	tsmKeyPrefix = append(tsmKeyPrefix, ',')
 
 	var stats cursors.CursorStats
 	var canceled bool
diff --git a/tsdb/tsm1/engine_measurement_schema_test.go b/tsdb/tsm1/engine_measurement_schema_test.go
index c46e4ea2dc..adbcd27275 100644
--- a/tsdb/tsm1/engine_measurement_schema_test.go
+++ b/tsdb/tsm1/engine_measurement_schema_test.go
@@ -532,6 +532,29 @@ memB,host=EB,os=macOS value=1.3 201`)
 			exp:      nil,
 			expStats: cursors.CursorStats{ScannedValues: 0, ScannedBytes: 0},
 		},
+		{
+			name: "prefix substring without predicate",
+			args: args{
+				org: 1,
+				m:   "cpu",
+				key: "host",
+				min: 0,
+				max: 1000,
+			},
+			expStats: cursors.CursorStats{},
+		},
+		{
+			name: "prefix substring with predicate",
+			args: args{
+				org:  1,
+				m:    "cpu",
+				key:  "host",
+				min:  0,
+				max:  1000,
+				expr: `os = 'linux'`,
+			},
+			expStats: cursors.CursorStats{},
+		},
 	}
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
@@ -793,6 +816,27 @@ mem,mem1=v,mem2=v        f=1 201`)
 			exp:      nil,
 			expStats: cursors.CursorStats{ScannedValues: 0, ScannedBytes: 0},
 		},
+		{
+			name: "prefix substring without predicate",
+			args: args{
+				org: 0,
+				m:   "cp",
+				min: 0,
+				max: 1000,
+			},
+			expStats: cursors.CursorStats{},
+		},
+		{
+			name: "prefix substring with predicate",
+			args: args{
+				org:  0,
+				m:    "cp",
+				min:  0,
+				max:  1000,
+				expr: `cpu = 'v'`,
+			},
+			expStats: cursors.CursorStats{},
+		},
 	}
 	for _, tc := range tests {
 		t.Run(fmt.Sprintf("org%d/%s", tc.args.org, tc.name), func(t *testing.T) {
@@ -1066,6 +1110,29 @@ m10,foo=v barS="60" 501
 			exp:      nil,
 			expStats: makeStats(0),
 		},
+		{
+			name: "prefix substring without predicate",
+			args: args{
+				org: 0,
+				m:   "m0",
+				min: 0,
+				max: 1000,
+			},
+			exp:      nil,
+			expStats: makeStats(0),
+		},
+		{
+			name: "prefix substring with predicate",
+			args: args{
+				org:  0,
+				m:    "m0",
+				min:  0,
+				max:  1000,
+				expr: `tag10 = 'v10'`,
+			},
+			exp:      nil,
+			expStats: makeStats(0),
+		},
 	}
 	for _, tc := range tests {
 		t.Run(fmt.Sprintf("org%d/%s", tc.args.org, tc.name), func(t *testing.T) {
diff --git a/tsdb/tsm1/engine_schema.go b/tsdb/tsm1/engine_schema.go
index 803af35c3b..4d70442cd9 100644
--- a/tsdb/tsm1/engine_schema.go
+++ b/tsdb/tsm1/engine_schema.go
@@ -53,6 +53,7 @@ func (e *Engine) tagValuesNoPredicate(ctx context.Context, orgID, bucketID influ
 		// append the measurement tag key to the prefix
 		mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 		tsmKeyPrefix = mt.AppendHashKey(tsmKeyPrefix)
+		tsmKeyPrefix = append(tsmKeyPrefix, ',')
 	}
 
 	// TODO(sgc): extend prefix when filtering by \x00 == <measurement>
@@ -181,6 +182,7 @@ func (e *Engine) tagValuesPredicate(ctx context.Context, orgID, bucketID influxd
 		// append the measurement tag key to the prefix
 		mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 		tsmKeyPrefix = mt.AppendHashKey(tsmKeyPrefix)
+		tsmKeyPrefix = append(tsmKeyPrefix, ',')
 	}
 
 	var canceled bool
@@ -349,6 +351,7 @@ func (e *Engine) tagKeysNoPredicate(ctx context.Context, orgID, bucketID influxd
 		// append the measurement tag key to the prefix
 		mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 		tsmKeyPrefix = mt.AppendHashKey(tsmKeyPrefix)
+		tsmKeyPrefix = append(tsmKeyPrefix, ',')
 	}
 
 	var keyset models.TagKeysSet
@@ -474,6 +477,7 @@ func (e *Engine) tagKeysPredicate(ctx context.Context, orgID, bucketID influxdb.
 		// append the measurement tag key to the prefix
 		mt := models.Tags{models.NewTag(models.MeasurementTagKeyBytes, measurement)}
 		tsmKeyPrefix = mt.AppendHashKey(tsmKeyPrefix)
+		tsmKeyPrefix = append(tsmKeyPrefix, ',')
 	}
 
 	var canceled bool