Fix bug with compact

pkg/bloomgateway/cache.go

@@ -108,22 +108,34 @@ func (m merger) MergeResponse(responses ...resultscache.Response) (resultscache.
 
 // Merge duplicated fingerprints by:
 // 1. Sort the chunkRefs by their stream fingerprint
-// 2. Append all chunks with the same fingerprint into the first fingerprint's chunk list.
+// 2. Remove duplicated FPs appending all chunks into the first fingerprint's chunk list.
 func mergeGroupedChunkRefs(chunkRefs []*logproto.GroupedChunkRefs) []*logproto.GroupedChunkRefs {
+	if len(chunkRefs) <= 1 {
+		return chunkRefs
+	}
+
 	sort.Slice(chunkRefs, func(i, j int) bool {
 		return chunkRefs[i].Fingerprint < chunkRefs[j].Fingerprint
 	})
-	return slices.CompactFunc(chunkRefs, func(next, prev *logproto.GroupedChunkRefs) bool {
-		if next.Fingerprint == prev.Fingerprint {
-			prev.Refs = mergeShortRefs(append(prev.Refs, next.Refs...))
-			return true
+
+	var lastDiffFP int
+	for i := 1; i < len(chunkRefs); i++ {
+		if chunkRefs[lastDiffFP].Fingerprint == chunkRefs[i].Fingerprint {
+			chunkRefs[lastDiffFP].Refs = mergeShortRefs(append(chunkRefs[lastDiffFP].Refs, chunkRefs[i].Refs...))
+		} else {
+			lastDiffFP++
+			chunkRefs[lastDiffFP] = chunkRefs[i]
 		}
-		return false
-	})
+	}
+	return chunkRefs[:lastDiffFP+1]
 }
 
 // mergeShortRefs merges short-refs by removing duplicated checksums.
 func mergeShortRefs(refs []*logproto.ShortRef) []*logproto.ShortRef {
+	if len(refs) <= 1 {
+		return refs
+	}
+
 	sort.Slice(refs, func(i, j int) bool {
 		return refs[i].Checksum < refs[j].Checksum
 	})

pkg/bloomgateway/cache_test.go

@@ -242,6 +242,27 @@ func TestMerge(t *testing.T) {
 						},
 					},
 				},
+				{
+					ChunkRefs: []*logproto.GroupedChunkRefs{
+						// Same FP as in previous input and diff chunks
+						{
+							Fingerprint: 2,
+							Tenant:      "fake",
+							Refs: []*logproto.ShortRef{
+								{
+									From:     700,
+									Through:  1000,
+									Checksum: 40,
+								},
+								{
+									From:     2000,
+									Through:  2700,
+									Checksum: 50,
+								},
+							},
+						},
+					},
+				},
 			},
 			expected: &logproto.FilterChunkRefResponse{
 				ChunkRefs: []*logproto.GroupedChunkRefs{
@@ -280,6 +301,16 @@ func TestMerge(t *testing.T) {
 								Through:  2500,
 								Checksum: 30,
 							},
+							{
+								From:     700,
+								Through:  1000,
+								Checksum: 40,
+							},
+							{
+								From:     2000,
+								Through:  2700,
+								Checksum: 50,
+							},
 						},
 					},
 					{