chore(dtaobj): add test for cleaning up metadata columns between buff…

…er flushes

pkg/dataobj/internal/sections/logs/table.go

@@ -3,7 +3,6 @@ package logs
 import (
 	"cmp"
 	"fmt"
-	"iter"
 	"slices"
 
 	"github.com/grafana/loki/v3/pkg/dataobj/internal/dataset"
@@ -139,11 +138,6 @@ func (b *tableBuffer) Metadata(key string, pageSize int, compressionOpts dataset
 	return col
 }
 
-// MetadataIter returns an iterator over the metadata columns.
-func (b *tableBuffer) MetadataIter() iter.Seq2[int, *dataset.ColumnBuilder] {
-	return slices.All(b.metadatas)
-}
-
 // Reset resets the buffer to its initial state.
 func (b *tableBuffer) Reset() {
 	if b.streamID != nil {

pkg/dataobj/internal/sections/logs/table_test.go

@@ -0,0 +1,35 @@
+package logs
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/loki/v3/pkg/dataobj/internal/dataset"
+)
+
+func Test_table_metadataCleanup(t *testing.T) {
+	var buf tableBuffer
+	initBuffer(&buf)
+
+	_ = buf.Metadata("foo", 1024, dataset.CompressionOptions{})
+	_ = buf.Metadata("bar", 1024, dataset.CompressionOptions{})
+
+	table, err := buf.Flush()
+	require.NoError(t, err)
+	require.Equal(t, 2, len(table.metadatas))
+
+	initBuffer(&buf)
+	_ = buf.Metadata("bar", 1024, dataset.CompressionOptions{})
+
+	table, err = buf.Flush()
+	require.NoError(t, err)
+	require.Equal(t, 1, len(table.metadatas))
+	require.Equal(t, "bar", table.metadatas[0].Info.Name)
+}
+
+func initBuffer(buf *tableBuffer) {
+	buf.StreamID(1024)
+	buf.Timestamp(1024)
+	buf.Message(1024, dataset.CompressionOptions{})
+}