diff --git a/db.go b/db.go
index 647be40ca..4afa50af0 100644
--- a/db.go
+++ b/db.go
@@ -19,18 +19,16 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"math"
 	"os"
 	"path/filepath"
 	"runtime"
 	"sort"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
-	"golang.org/x/sync/errgroup"
-
-	"strings"
-
 	"github.com/go-kit/kit/log"
 	"github.com/go-kit/kit/log/level"
 	"github.com/nightlyone/lockfile"
@@ -40,6 +38,7 @@ import (
 	"github.com/prometheus/tsdb/chunkenc"
 	"github.com/prometheus/tsdb/fileutil"
 	"github.com/prometheus/tsdb/labels"
+	"golang.org/x/sync/errgroup"
 )
 
 // DefaultOptions used for the DB. They are sane for setups using
@@ -570,21 +569,22 @@ func validateBlockSequence(bs []*Block) error {
 
 	overlaps := OverlappingBlocks(metas)
 	if len(overlaps) > 0 {
-		return errors.Errorf("block time ranges overlap: %s", PrintOverlappedBlocks(overlaps))
+		return errors.Errorf("block time ranges overlap: %s", SprintOverlappedBlocks(overlaps))
 	}
 
 	return nil
 }
 
 type TimeRange struct {
-	MaxTime, MinTime int64
+	Min, Max int64
 }
-// OverlappingBlocks returns all overlapping blocks from given meta files.
+
+// OverlappingBlocks returns all overlapping blocks from given meta files aggregated by overlaping range.
 // We sort blocks by minTime. Then we iterate over each block minTime and treat it as our "current" timestamp.
 // We check all the pending blocks (blocks that we have seen their minTimes, but their maxTime was still ahead current
-// timestamp) if they did not finish. If not, it means they overlap with our current b. In the same time b is assumed as
+// timestamp) if they finish. If not, it means they overlap with our current b. In the same time b is assumed as
 // pending.
-func OverlappingBlocks(bm []BlockMeta) (overlaps [][]BlockMeta) {
+func OverlappingBlocks(bm []BlockMeta) map[TimeRange][]BlockMeta {
 	if len(bm) <= 1 {
 		return nil
 	}
@@ -593,6 +593,8 @@ func OverlappingBlocks(bm []BlockMeta) (overlaps [][]BlockMeta) {
 	})
 
 	var (
+		overlaps [][]BlockMeta
+
 		// pending contains not ended blocks in regards to "current" timestamp.
 		pending = []BlockMeta{bm[0]}
 		// continuousPending helps to aggregate same overlaps to single group.
@@ -627,13 +629,31 @@ func OverlappingBlocks(bm []BlockMeta) (overlaps [][]BlockMeta) {
 		// Start new pendings.
 		continuousPending = true
 	}
-	return overlaps
+
+	// Fetch the critical overlapped time range foreach overlap groups.
+	overlapGroups := map[TimeRange][]BlockMeta{}
+	for _, overlap := range overlaps {
+
+		minRange := TimeRange{Min: 0, Max: math.MaxInt64}
+		for _, b := range overlap {
+			if minRange.Max > b.MaxTime {
+				minRange.Max = b.MaxTime
+			}
+
+			if minRange.Min < b.MinTime {
+				minRange.Min = b.MinTime
+			}
+		}
+		overlapGroups[minRange] = overlap
+	}
+
+	return overlapGroups
 }
 
-// PrintOverlappedBlocks returns human readable string form of overlapped blocks.
-func PrintOverlappedBlocks(overlaps [][]BlockMeta) string {
+// SprintOverlappedBlocks returns human readable string form of overlapped blocks.
+func SprintOverlappedBlocks(overlaps map[TimeRange][]BlockMeta) string {
 	var res []string
-	for _, o := range overlaps {
+	for r, o := range overlaps {
 		var groups []string
 		for _, m := range o {
 			groups = append(groups, fmt.Sprintf(
@@ -644,7 +664,7 @@ func PrintOverlappedBlocks(overlaps [][]BlockMeta) string {
 				(time.Duration((m.MaxTime-m.MinTime)/1000)*time.Second).String(),
 			))
 		}
-		res = append(res, fmt.Sprintf("<%s>", strings.Join(groups, "")))
+		res = append(res, fmt.Sprintf("[%d %d]: <%s> ", r.Min, r.Max, strings.Join(groups, "")))
 	}
 	return strings.Join(res, "")
 }
diff --git a/db_test.go b/db_test.go
index fd45a392f..451ea91e8 100644
--- a/db_test.go
+++ b/db_test.go
@@ -907,47 +907,57 @@ func TestOverlappingBlocksDetectsAllOverlaps(t *testing.T) {
 
 	// o1 overlaps with 10-20.
 	o1 := BlockMeta{MinTime: 15, MaxTime: 17}
-	testutil.Equals(t, [][]BlockMeta{{metas[1], o1}}, OverlappingBlocks(append(metas, o1)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 15, Max: 17}: {metas[1], o1},
+	}, OverlappingBlocks(append(metas, o1)))
 
 	// o2 overlaps with 20-30 and 30-40.
 	o2 := BlockMeta{MinTime: 21, MaxTime: 31}
-	testutil.Equals(t, [][]BlockMeta{{metas[2], o2}, {o2, metas[3]}}, OverlappingBlocks(append(metas, o2)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 21, Max: 30}: {metas[2], o2},
+		{Min: 30, Max: 31}: {o2, metas[3]},
+	}, OverlappingBlocks(append(metas, o2)))
 
 	// o3a and o3b overlaps with 30-40 and each other.
 	o3a := BlockMeta{MinTime: 33, MaxTime: 39}
 	o3b := BlockMeta{MinTime: 34, MaxTime: 36}
-	testutil.Equals(t, [][]BlockMeta{{metas[3], o3a, o3b}}, OverlappingBlocks(append(metas, o3a, o3b)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 34, Max: 36}: {metas[3], o3a, o3b},
+	}, OverlappingBlocks(append(metas, o3a, o3b)))
 
 	// o4 is 1:1 overlap with 50-60.
 	o4 := BlockMeta{MinTime: 50, MaxTime: 60}
-	testutil.Equals(t, [][]BlockMeta{{metas[5], o4}}, OverlappingBlocks(append(metas, o4)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 50, Max: 60}: {metas[5], o4},
+	}, OverlappingBlocks(append(metas, o4)))
 
 	// o5 overlaps with 60-70, 70-80 and 80-90.
 	o5 := BlockMeta{MinTime: 61, MaxTime: 85}
-	testutil.Equals(t, [][]BlockMeta{{metas[6], o5}, {o5, metas[7]}, {o5, metas[8]}}, OverlappingBlocks(append(metas, o5)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 61, Max: 70}: {metas[6], o5},
+		{Min: 70, Max: 80}: {o5, metas[7]},
+		{Min: 80, Max: 85}: {o5, metas[8]},
+	}, OverlappingBlocks(append(metas, o5)))
 
 	// o6a overlaps with 90-100, 100-110 and o6b, o6b overlaps with 90-100 and o6a.
 	o6a := BlockMeta{MinTime: 92, MaxTime: 105}
 	o6b := BlockMeta{MinTime: 94, MaxTime: 99}
-	testutil.Equals(t, [][]BlockMeta{{metas[9], o6a, o6b}, {o6a, metas[10]}}, OverlappingBlocks(append(metas, o6a, o6b)))
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 94, Max: 99}:   {metas[9], o6a, o6b},
+		{Min: 100, Max: 105}: {o6a, metas[10]},
+	}, OverlappingBlocks(append(metas, o6a, o6b)))
 
 	// All together.
-	testutil.Equals(t, [][]BlockMeta{
-		{metas[1], o1},
-		{metas[2], o2}, {o2, metas[3]},
-		{metas[3], o3a, o3b},
-		{metas[5], o4},
-		{metas[6], o5}, {o5, metas[7]}, {o5, metas[8]},
-		{metas[9], o6a, o6b}, {o6a, metas[10]},
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 15, Max: 17}: {metas[1], o1},
+		{Min: 21, Max: 30}: {metas[2], o2}, {Min: 30, Max: 31}: {o2, metas[3]},
+		{Min: 34, Max: 36}: {metas[3], o3a, o3b},
+		{Min: 50, Max: 60}: {metas[5], o4},
+		{Min: 61, Max: 70}: {metas[6], o5}, {Min: 70, Max: 80}: {o5, metas[7]}, {Min: 80, Max: 85}: {o5, metas[8]},
+		{Min: 94, Max: 99}: {metas[9], o6a, o6b}, {Min: 100, Max: 105}: {o6a, metas[10]},
 	}, OverlappingBlocks(append(metas, o1, o2, o3a, o3b, o4, o5, o6a, o6b)))
 
-	// Additional cases.
-	a1 := BlockMeta{MinTime: 1, MaxTime: 5}
-	a2 := BlockMeta{MinTime: 1, MaxTime: 2}
-	a3 := BlockMeta{MinTime: 3, MaxTime: 4}
-	a4 := BlockMeta{MinTime: 3, MaxTime: 4}
-	testutil.Equals(t, [][]BlockMeta{{a1, a2}, {a1, a3, a4}}, OverlappingBlocks(append([]BlockMeta{a1}, a2, a3, a4)))
-
+	// Additional case.
 	var nc1 []BlockMeta
 	nc1 = append(nc1, BlockMeta{MinTime: 1, MaxTime: 5})
 	nc1 = append(nc1, BlockMeta{MinTime: 2, MaxTime: 3})
@@ -959,10 +969,10 @@ func TestOverlappingBlocksDetectsAllOverlaps(t *testing.T) {
 	nc1 = append(nc1, BlockMeta{MinTime: 5, MaxTime: 7})
 	nc1 = append(nc1, BlockMeta{MinTime: 7, MaxTime: 10})
 	nc1 = append(nc1, BlockMeta{MinTime: 8, MaxTime: 9})
-	testutil.Equals(t, [][]BlockMeta{
-		{nc1[0], nc1[1], nc1[2], nc1[3], nc1[4], nc1[5]}, // 1-5, 2-3, 2-3, 2-3, 2-3, 2,6
-		{nc1[0], nc1[5], nc1[6]}, // 1-5, 2-6, 3-5
-		{nc1[5], nc1[7]}, // 2-6, 5-7
-		{nc1[8], nc1[9]}, // 7-10, 8-9
+	testutil.Equals(t, map[TimeRange][]BlockMeta{
+		{Min: 2, Max: 3}: {nc1[0], nc1[1], nc1[2], nc1[3], nc1[4], nc1[5]}, // 1-5, 2-3, 2-3, 2-3, 2-3, 2,6
+		{Min: 3, Max: 5}: {nc1[0], nc1[5], nc1[6]},                         // 1-5, 2-6, 3-5
+		{Min: 5, Max: 6}: {nc1[5], nc1[7]},                                 // 2-6, 5-7
+		{Min: 8, Max: 9}: {nc1[8], nc1[9]},                                 // 7-10, 8-9
 	}, OverlappingBlocks(nc1))
 }