Repair non-empty XOR chunks during 1h downsampling

Iterated through the non empty XOR chunks, stored the results in a buffer and then downsampled them to 5m aggregated chunks by using DownsampleRaw method and then passed them for 1h downsampling.

Signed-off-by: Kartik-Garg <[email protected]>

pkg/compact/downsample/downsample.go

@@ -167,10 +167,23 @@ func Downsample(
 						// https://github.com/thanos-io/thanos/issues/5272
 						level.Warn(logger).Log("msg", fmt.Sprintf("expected downsampled chunk (*downsample.AggrChunk) got an empty %T instead for series: %d", c.Chunk, postings.At()))
 						continue
+					} else {
+						if err := expandChunkIterator(c.Chunk.Iterator(reuseIt), &all); err != nil {
+							return id, errors.Wrapf(err, "expand chunk %d, series %d", c.Ref, postings.At())
+						}
+						aggrDataChunks := DownsampleRaw(all, ResLevel1)
+						for _, cn := range aggrDataChunks {
+							ac, ok = cn.Chunk.(*AggrChunk)
+							if !ok {
+								level.Warn(logger).Log("Not able to convert non-empty XOR chunks into 5m downsampled Aggregated chunks")
+								continue
+							}
+						}
+
 					}
-					return id, errors.Errorf("expected downsampled chunk (*downsample.AggrChunk) got a non-empty %T instead for series: %d", c.Chunk, postings.At())
 				}
 				aggrChunks = append(aggrChunks, ac)
+
 			}
 			downsampledChunks, err := downsampleAggr(
 				aggrChunks,

pkg/compact/downsample/downsample_test.go

@@ -552,6 +552,7 @@ func TestDownsampleAggrAndNonEmptyXORChunks(t *testing.T) {
 	raw := chunkenc.NewXORChunk()
 	app, err := raw.Appender()
 	testutil.Ok(t, err)
+	// this comes in !ok and passes through our newly created funcionality
 	app.Append(1587690005794, 42.5)
 	ser.chunks = append(ser.chunks, encodeTestAggrSeries(aggr), chunks.Meta{
 		MinTime: math.MaxInt64,
@@ -563,10 +564,12 @@ func TestDownsampleAggrAndNonEmptyXORChunks(t *testing.T) {
 	mb.addSeries(ser)
 
 	fakeMeta := &metadata.Meta{}
+	// target
 	fakeMeta.Thanos.Downsample.Resolution = 300_000
+	// already existing resolution
 	id, err := Downsample(logger, fakeMeta, mb, dir, 3_600_000)
 	_ = id
-	testutil.NotOk(t, err)
+	testutil.Ok(t, err)
 }
 
 func chunksToSeriesIteratable(t *testing.T, inRaw [][]sample, inAggr []map[AggrType][]sample) *series {