db: add test for chunks that span beyond a block's boundaries

Signed-off-by: Benoît Knecht <benoit.knecht@fsfe.org>

db_test.go

@@ -26,6 +26,8 @@ import (
 
 	"github.com/oklog/ulid"
 	"github.com/pkg/errors"
+	"github.com/prometheus/tsdb/chunks"
+	"github.com/prometheus/tsdb/index"
 	"github.com/prometheus/tsdb/labels"
 	"github.com/prometheus/tsdb/testutil"
 )
@@ -1096,3 +1098,58 @@ func TestOverlappingBlocksDetectsAllOverlaps(t *testing.T) {
 		{Min: 8, Max: 9}: {nc1[8], nc1[9]},                                 // 7-10, 8-9
 	}, OverlappingBlocks(nc1))
 }
+
+// Regression test for https://github.com/prometheus/tsdb/issues/347
+func TestChunkAtBlockBoundary(t *testing.T) {
+	db, close := openTestDB(t, nil)
+	defer close()
+	defer db.Close()
+
+	app := db.Appender()
+
+	blockRange := DefaultOptions.BlockRanges[0]
+	label := labels.FromStrings("foo", "bar")
+
+	for i := int64(0); i < 3; i++ {
+		_, err := app.Add(label, i*blockRange, 0)
+		testutil.Ok(t, err)
+		_, err = app.Add(label, i*blockRange+1000, 0)
+		testutil.Ok(t, err)
+	}
+
+	err := app.Commit()
+	testutil.Ok(t, err)
+
+	_, err = db.compact()
+	testutil.Ok(t, err)
+
+	for _, block := range db.blocks {
+		r, err := block.Index()
+		testutil.Ok(t, err)
+		defer r.Close()
+
+		meta := block.Meta()
+
+		p, err := r.Postings(index.AllPostingsKey())
+		testutil.Ok(t, err)
+
+		var (
+			lset labels.Labels
+			chks []chunks.Meta
+		)
+
+		chunkCount := 0
+
+		for p.Next() {
+			err = r.Series(p.At(), &lset, &chks)
+			testutil.Ok(t, err)
+			for _, c := range chks {
+				testutil.Assert(t, meta.MinTime <= c.MinTime && c.MaxTime <= meta.MaxTime,
+					"chunk spans beyond block boundaries: [block.MinTime=%d, block.MaxTime=%d]; [chunk.MinTime=%d, chunk.MaxTime=%d]",
+					meta.MinTime, meta.MaxTime, c.MinTime, c.MaxTime)
+				chunkCount++
+			}
+		}
+		testutil.Assert(t, chunkCount == 1, "expected 1 chunk in block %s, got %d", meta.ULID, chunkCount)
+	}
+}