Fix histogram append errors (#13201)

* Fix histogram append errors

We should check counterReset condition rather than okToAppend because if
there's a counter reset, okToAppend is always set to false.

Signed-off-by: Fiona Liao <fiona.y.liao@gmail.com>

tsdb/chunkenc/float_histogram.go

@@ -605,10 +605,10 @@ func (a *FloatHistogramAppender) AppendFloatHistogram(prev *FloatHistogramAppend
 		pForwardInserts, nForwardInserts, okToAppend, counterReset := a.appendable(h)
 		if !okToAppend || counterReset {
 			if appendOnly {
-				if !okToAppend {
-					return nil, false, a, fmt.Errorf("float histogram schema change")
+				if counterReset {
+					return nil, false, a, fmt.Errorf("float histogram counter reset")
 				}
-				return nil, false, a, fmt.Errorf("float histogram counter reset")
+				return nil, false, a, fmt.Errorf("float histogram schema change")
 			}
 			newChunk := NewFloatHistogramChunk()
 			app, err := newChunk.Appender()

tsdb/chunkenc/float_histogram_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/prometheus/prometheus/model/histogram"
+	"github.com/prometheus/prometheus/tsdb/tsdbutil"
 )
 
 type floatResult struct {
@@ -928,3 +929,50 @@ func TestFloatHistogramChunkAppendableGauge(t *testing.T) {
 		assertRecodedFloatHistogramChunkOnAppend(t, c, hApp, ts+1, h2, GaugeType)
 	}
 }
+
+func TestFloatHistogramAppendOnlyErrors(t *testing.T) {
+	t.Run("schema change error", func(t *testing.T) {
+		c := Chunk(NewFloatHistogramChunk())
+
+		// Create fresh appender and add the first histogram.
+		app, err := c.Appender()
+		require.NoError(t, err)
+
+		h := tsdbutil.GenerateTestFloatHistogram(0)
+		var isRecoded bool
+		c, isRecoded, app, err = app.AppendFloatHistogram(nil, 1, h, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.NoError(t, err)
+
+		// Add erroring histogram.
+		h2 := h.Copy()
+		h2.Schema++
+		c, isRecoded, _, err = app.AppendFloatHistogram(nil, 2, h2, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.EqualError(t, err, "float histogram schema change")
+	})
+	t.Run("counter reset error", func(t *testing.T) {
+		c := Chunk(NewFloatHistogramChunk())
+
+		// Create fresh appender and add the first histogram.
+		app, err := c.Appender()
+		require.NoError(t, err)
+
+		h := tsdbutil.GenerateTestFloatHistogram(0)
+		var isRecoded bool
+		c, isRecoded, app, err = app.AppendFloatHistogram(nil, 1, h, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.NoError(t, err)
+
+		// Add erroring histogram.
+		h2 := h.Copy()
+		h2.CounterResetHint = histogram.CounterReset
+		c, isRecoded, _, err = app.AppendFloatHistogram(nil, 2, h2, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.EqualError(t, err, "float histogram counter reset")
+	})
+}

tsdb/chunkenc/histogram.go

@@ -640,10 +640,10 @@ func (a *HistogramAppender) AppendHistogram(prev *HistogramAppender, t int64, h
 		pForwardInserts, nForwardInserts, okToAppend, counterReset := a.appendable(h)
 		if !okToAppend || counterReset {
 			if appendOnly {
-				if !okToAppend {
-					return nil, false, a, fmt.Errorf("histogram schema change")
+				if counterReset {
+					return nil, false, a, fmt.Errorf("histogram counter reset")
 				}
-				return nil, false, a, fmt.Errorf("histogram counter reset")
+				return nil, false, a, fmt.Errorf("histogram schema change")
 			}
 			newChunk := NewHistogramChunk()
 			app, err := newChunk.Appender()

tsdb/chunkenc/histogram_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/prometheus/prometheus/model/histogram"
+	"github.com/prometheus/prometheus/tsdb/tsdbutil"
 )
 
 type result struct {
@@ -1129,3 +1130,50 @@ func TestHistogramChunkAppendableGauge(t *testing.T) {
 		require.Equal(t, GaugeType, c.(*HistogramChunk).GetCounterResetHeader())
 	}
 }
+
+func TestHistogramAppendOnlyErrors(t *testing.T) {
+	t.Run("schema change error", func(t *testing.T) {
+		c := Chunk(NewHistogramChunk())
+
+		// Create fresh appender and add the first histogram.
+		app, err := c.Appender()
+		require.NoError(t, err)
+
+		h := tsdbutil.GenerateTestHistogram(0)
+		var isRecoded bool
+		c, isRecoded, app, err = app.AppendHistogram(nil, 1, h, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.NoError(t, err)
+
+		// Add erroring histogram.
+		h2 := h.Copy()
+		h2.Schema++
+		c, isRecoded, _, err = app.AppendHistogram(nil, 2, h2, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.EqualError(t, err, "histogram schema change")
+	})
+	t.Run("counter reset error", func(t *testing.T) {
+		c := Chunk(NewHistogramChunk())
+
+		// Create fresh appender and add the first histogram.
+		app, err := c.Appender()
+		require.NoError(t, err)
+
+		h := tsdbutil.GenerateTestHistogram(0)
+		var isRecoded bool
+		c, isRecoded, app, err = app.AppendHistogram(nil, 1, h, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.NoError(t, err)
+
+		// Add erroring histogram.
+		h2 := h.Copy()
+		h2.CounterResetHint = histogram.CounterReset
+		c, isRecoded, _, err = app.AppendHistogram(nil, 2, h2, true)
+		require.Nil(t, c)
+		require.False(t, isRecoded)
+		require.EqualError(t, err, "histogram counter reset")
+	})
+}