diff --git a/pkg/rhh/rhh.go b/pkg/rhh/rhh.go
index f4e7f42959..0530715900 100644
--- a/pkg/rhh/rhh.go
+++ b/pkg/rhh/rhh.go
@@ -244,15 +244,9 @@ func HashKey(key []byte) int64 {
 
 // HashUint64 computes a hash of an int64. Hash is always non-zero.
 func HashUint64(key uint64) int64 {
-	hash := xxhash.New()
-	binary.Write(hash, binary.BigEndian, key)
-	h := int64(hash.Sum64())
-	if h == 0 {
-		h = 1
-	} else if h < 0 {
-		h = 0 - h
-	}
-	return h
+	buf := make([]byte, 8)
+	binary.BigEndian.PutUint64(buf, key)
+	return HashKey(buf)
 }
 
 // Dist returns the probe distance for a hash in a slot index.
diff --git a/tsdb/series_file.go b/tsdb/series_file.go
index 1178b1476d..b1a8599fdd 100644
--- a/tsdb/series_file.go
+++ b/tsdb/series_file.go
@@ -666,7 +666,14 @@ func (c *SeriesFileCompactor) compactIndexTo(index *SeriesIndex, seriesN uint64,
 
 	// Reindex all partitions.
 	for _, segment := range segments {
+		errDone := errors.New("done")
+
 		if err := segment.ForEachEntry(func(flag uint8, id uint64, offset int64, key []byte) error {
+			// Make sure we don't go past the offset where the compaction began.
+			if offset >= index.maxOffset {
+				return errDone
+			}
+
 			// Only process insert entries.
 			switch flag {
 			case SeriesEntryInsertFlag: // fallthrough
@@ -681,13 +688,15 @@ func (c *SeriesFileCompactor) compactIndexTo(index *SeriesIndex, seriesN uint64,
 				return nil
 			}
 
-			// Save highest id/offset to header.
+			// Save max series identifier processed.
 			hdr.MaxSeriesID, hdr.MaxOffset = id, offset
 
 			// Insert into maps.
 			c.insertIDOffsetMap(idOffsetMap, hdr.Capacity, id, offset)
 			return c.insertKeyIDMap(keyIDMap, hdr.Capacity, segments, key, offset, id)
-		}); err != nil {
+		}); err == errDone {
+			break
+		} else if err != nil {
 			return err
 		}
 	}
@@ -730,7 +739,8 @@ func (c *SeriesFileCompactor) insertKeyIDMap(dst []byte, capacity int64, segment
 	hash := rhh.HashKey(key)
 
 	// Continue searching until we find an empty slot or lower probe distance.
-	for dist, pos := int64(0), hash&mask; ; dist, pos = dist+1, (pos+1)&mask {
+	for i, dist, pos := int64(0), int64(0), hash&mask; ; i, dist, pos = i+1, dist+1, (pos+1)&mask {
+		assert(i <= capacity, "key/id map full")
 		elem := dst[(pos * SeriesIndexElemSize):]
 
 		// If empty slot found or matching offset, insert and exit.
@@ -749,7 +759,6 @@ func (c *SeriesFileCompactor) insertKeyIDMap(dst []byte, capacity int64, segment
 		// If the existing elem has probed less than us, then swap places with
 		// existing elem, and keep going to find another slot for that elem.
 		if d := rhh.Dist(elemHash, pos, capacity); d < dist {
-
 			// Insert current values.
 			binary.BigEndian.PutUint64(elem[:8], uint64(offset))
 			binary.BigEndian.PutUint64(elem[8:], id)
@@ -769,6 +778,7 @@ func (c *SeriesFileCompactor) insertIDOffsetMap(dst []byte, capacity int64, id u
 
 	// Continue searching until we find an empty slot or lower probe distance.
 	for i, dist, pos := int64(0), int64(0), hash&mask; ; i, dist, pos = i+1, dist+1, (pos+1)&mask {
+		assert(i <= capacity, "id/offset map full")
 		elem := dst[(pos * SeriesIndexElemSize):]
 
 		// If empty slot found or matching id, insert and exit.
@@ -796,10 +806,6 @@ func (c *SeriesFileCompactor) insertIDOffsetMap(dst []byte, capacity int64, id u
 			// Update current distance.
 			dist = d
 		}
-
-		if i > capacity {
-			panic("rhh map full")
-		}
 	}
 }
 
diff --git a/tsdb/series_index.go b/tsdb/series_index.go
index 078d0f1776..dbcff6ecb4 100644
--- a/tsdb/series_index.go
+++ b/tsdb/series_index.go
@@ -165,6 +165,13 @@ func (idx *SeriesIndex) execEntry(flag uint8, id uint64, offset int64, key []byt
 		idx.keyIDMap.Put(key, id)
 		idx.idOffsetMap[id] = offset
 
+		if id > idx.maxSeriesID {
+			idx.maxSeriesID = id
+		}
+		if offset > idx.maxOffset {
+			idx.maxOffset = offset
+		}
+
 	case SeriesEntryTombstoneFlag:
 		idx.tombstones[id] = struct{}{}
 
@@ -255,6 +262,8 @@ func (idx *SeriesIndex) Clone() *SeriesIndex {
 		count:        idx.count,
 		capacity:     idx.capacity,
 		mask:         idx.mask,
+		maxSeriesID:  idx.maxSeriesID,
+		maxOffset:    idx.maxOffset,
 		data:         idx.data,
 		keyIDData:    idx.keyIDData,
 		idOffsetData: idx.idOffsetData,