From 34230bb17293535b65a53e33cbaf626663a679c3 Mon Sep 17 00:00:00 2001
From: Bryan Boreham <bjboreham@gmail.com>
Date: Mon, 27 Nov 2023 17:20:27 +0000
Subject: [PATCH 01/12] tsdb/wlog: close segment files sooner

'defer' runs at the end of the whole function; we should close each
segment file as soon as we finished reading it.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
---
 tsdb/wlog/watcher.go      | 5 +++--
 tsdb/wlog/watcher_test.go | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/tsdb/wlog/watcher.go b/tsdb/wlog/watcher.go
index 1c76e38877..56cd0cc4e2 100644
--- a/tsdb/wlog/watcher.go
+++ b/tsdb/wlog/watcher.go
@@ -730,10 +730,11 @@ func (w *Watcher) readCheckpoint(checkpointDir string, readFn segmentReadFn) err
 		if err != nil {
 			return fmt.Errorf("unable to open segment: %w", err)
 		}
-		defer sr.Close()
 
 		r := NewLiveReader(w.logger, w.readerMetrics, sr)
-		if err := readFn(w, r, index, false); err != nil && !errors.Is(err, io.EOF) {
+		err = readFn(w, r, index, false)
+		sr.Close()
+		if err != nil && !errors.Is(err, io.EOF) {
 			return fmt.Errorf("readSegment: %w", err)
 		}
 
diff --git a/tsdb/wlog/watcher_test.go b/tsdb/wlog/watcher_test.go
index b30dce91a3..2686d3bc9a 100644
--- a/tsdb/wlog/watcher_test.go
+++ b/tsdb/wlog/watcher_test.go
@@ -218,11 +218,11 @@ func TestTailSamples(t *testing.T) {
 			for i := first; i <= last; i++ {
 				segment, err := OpenReadSegment(SegmentName(watcher.walDir, i))
 				require.NoError(t, err)
-				defer segment.Close()
 
 				reader := NewLiveReader(nil, NewLiveReaderMetrics(nil), segment)
 				// Use tail true so we can ensure we got the right number of samples.
 				watcher.readSegment(reader, i, true)
+				require.NoError(t, segment.Close())
 			}
 
 			expectedSeries := seriesCount

From c04924bc41982dfef9ea29939c1a2c6fe56333c7 Mon Sep 17 00:00:00 2001
From: Arve Knudsen <arve.knudsen@gmail.com>
Date: Wed, 24 Jul 2024 16:47:33 +0200
Subject: [PATCH 02/12] otlptranslator: Add tests for BuildCompliantName

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
---
 .../prometheus/normalize_label.go             |  11 +-
 .../prometheus/normalize_name.go              |  25 +--
 .../prometheus/normalize_name_test.go         | 203 ++++++++++++++++++
 .../prometheus/testutils_test.go              |  49 +++++
 4 files changed, 270 insertions(+), 18 deletions(-)
 create mode 100644 storage/remote/otlptranslator/prometheus/normalize_name_test.go
 create mode 100644 storage/remote/otlptranslator/prometheus/testutils_test.go

diff --git a/storage/remote/otlptranslator/prometheus/normalize_label.go b/storage/remote/otlptranslator/prometheus/normalize_label.go
index 6360aa9765..a112b9bbce 100644
--- a/storage/remote/otlptranslator/prometheus/normalize_label.go
+++ b/storage/remote/otlptranslator/prometheus/normalize_label.go
@@ -21,15 +21,14 @@ import (
 	"unicode"
 )
 
-// Normalizes the specified label to follow Prometheus label names standard
+// Normalizes the specified label to follow Prometheus label names standard.
 //
-// See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
+// See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels.
 //
-// Labels that start with non-letter rune will be prefixed with "key_"
+// Labels that start with non-letter rune will be prefixed with "key_".
 //
-// Exception is made for double-underscores which are allowed
+// An exception is made for double-underscores which are allowed.
 func NormalizeLabel(label string) string {
-
 	// Trivial case
 	if len(label) == 0 {
 		return label
@@ -48,7 +47,7 @@ func NormalizeLabel(label string) string {
 	return label
 }
 
-// Return '_' for anything non-alphanumeric
+// Return '_' for anything non-alphanumeric.
 func sanitizeRune(r rune) rune {
 	if unicode.IsLetter(r) || unicode.IsDigit(r) {
 		return r
diff --git a/storage/remote/otlptranslator/prometheus/normalize_name.go b/storage/remote/otlptranslator/prometheus/normalize_name.go
index 71bba40e48..0f472b80a0 100644
--- a/storage/remote/otlptranslator/prometheus/normalize_name.go
+++ b/storage/remote/otlptranslator/prometheus/normalize_name.go
@@ -76,14 +76,15 @@ var perUnitMap = map[string]string{
 	"y":  "year",
 }
 
-// BuildCompliantName builds a Prometheus-compliant metric name for the specified metric
+// BuildCompliantName builds a Prometheus-compliant metric name for the specified metric.
 //
 // Metric name is prefixed with specified namespace and underscore (if any).
 // Namespace is not cleaned up. Make sure specified namespace follows Prometheus
 // naming convention.
 //
-// See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels
-// and https://prometheus.io/docs/practices/naming/#metric-and-label-naming
+// See rules at https://prometheus.io/docs/concepts/data_model/#metric-names-and-labels,
+// https://prometheus.io/docs/practices/naming/#metric-and-label-naming
+// and https://github.com/open-telemetry/opentelemetry-specification/blob/v1.33.0/specification/compatibility/prometheus_and_openmetrics.md#otlp-metric-points-to-prometheus.
 func BuildCompliantName(metric pmetric.Metric, namespace string, addMetricSuffixes bool) string {
 	var metricName string
 
@@ -110,7 +111,7 @@ func BuildCompliantName(metric pmetric.Metric, namespace string, addMetricSuffix
 
 // Build a normalized name for the specified metric
 func normalizeName(metric pmetric.Metric, namespace string) string {
-	// Split metric name in "tokens" (remove all non-alphanumeric)
+	// Split metric name into "tokens" (remove all non-alphanumerics)
 	nameTokens := strings.FieldsFunc(
 		metric.Name(),
 		func(r rune) bool { return !unicode.IsLetter(r) && !unicode.IsDigit(r) },
@@ -122,9 +123,9 @@ func normalizeName(metric pmetric.Metric, namespace string) string {
 	// Main unit
 	// Append if not blank, doesn't contain '{}', and is not present in metric name already
 	if len(unitTokens) > 0 {
-		mainUnitOtel := strings.TrimSpace(unitTokens[0])
-		if mainUnitOtel != "" && !strings.ContainsAny(mainUnitOtel, "{}") {
-			mainUnitProm := CleanUpString(unitMapGetOrDefault(mainUnitOtel))
+		mainUnitOTel := strings.TrimSpace(unitTokens[0])
+		if mainUnitOTel != "" && !strings.ContainsAny(mainUnitOTel, "{}") {
+			mainUnitProm := CleanUpString(unitMapGetOrDefault(mainUnitOTel))
 			if mainUnitProm != "" && !contains(nameTokens, mainUnitProm) {
 				nameTokens = append(nameTokens, mainUnitProm)
 			}
@@ -133,11 +134,11 @@ func normalizeName(metric pmetric.Metric, namespace string) string {
 		// Per unit
 		// Append if not blank, doesn't contain '{}', and is not present in metric name already
 		if len(unitTokens) > 1 && unitTokens[1] != "" {
-			perUnitOtel := strings.TrimSpace(unitTokens[1])
-			if perUnitOtel != "" && !strings.ContainsAny(perUnitOtel, "{}") {
-				perUnitProm := CleanUpString(perUnitMapGetOrDefault(perUnitOtel))
+			perUnitOTel := strings.TrimSpace(unitTokens[1])
+			if perUnitOTel != "" && !strings.ContainsAny(perUnitOTel, "{}") {
+				perUnitProm := CleanUpString(perUnitMapGetOrDefault(perUnitOTel))
 				if perUnitProm != "" && !contains(nameTokens, perUnitProm) {
-					nameTokens = append(append(nameTokens, "per"), perUnitProm)
+					nameTokens = append(nameTokens, "per", perUnitProm)
 				}
 			}
 		}
@@ -150,7 +151,7 @@ func normalizeName(metric pmetric.Metric, namespace string) string {
 	}
 
 	// Append _ratio for metrics with unit "1"
-	// Some Otel receivers improperly use unit "1" for counters of objects
+	// Some OTel receivers improperly use unit "1" for counters of objects
 	// See https://github.com/open-telemetry/opentelemetry-collector-contrib/issues?q=is%3Aissue+some+metric+units+don%27t+follow+otel+semantic+conventions
 	// Until these issues have been fixed, we're appending `_ratio` for gauges ONLY
 	// Theoretically, counters could be ratios as well, but it's absurd (for mathematical reasons)
diff --git a/storage/remote/otlptranslator/prometheus/normalize_name_test.go b/storage/remote/otlptranslator/prometheus/normalize_name_test.go
new file mode 100644
index 0000000000..ee25bb2dff
--- /dev/null
+++ b/storage/remote/otlptranslator/prometheus/normalize_name_test.go
@@ -0,0 +1,203 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// Provenance-includes-location: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/95e8f8fdc2a9dc87230406c9a3cf02be4fd68bea/pkg/translator/prometheus/normalize_name_test.go
+// Provenance-includes-license: Apache-2.0
+// Provenance-includes-copyright: Copyright The OpenTelemetry Authors.
+
+package prometheus
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/pdata/pmetric"
+)
+
+func TestByte(t *testing.T) {
+	require.Equal(t, "system_filesystem_usage_bytes", normalizeName(createGauge("system.filesystem.usage", "By"), ""))
+}
+
+func TestByteCounter(t *testing.T) {
+	require.Equal(t, "system_io_bytes_total", normalizeName(createCounter("system.io", "By"), ""))
+	require.Equal(t, "network_transmitted_bytes_total", normalizeName(createCounter("network_transmitted_bytes_total", "By"), ""))
+}
+
+func TestWhiteSpaces(t *testing.T) {
+	require.Equal(t, "system_filesystem_usage_bytes", normalizeName(createGauge("\t system.filesystem.usage       ", "  By\t"), ""))
+}
+
+func TestNonStandardUnit(t *testing.T) {
+	require.Equal(t, "system_network_dropped", normalizeName(createGauge("system.network.dropped", "{packets}"), ""))
+}
+
+func TestNonStandardUnitCounter(t *testing.T) {
+	require.Equal(t, "system_network_dropped_total", normalizeName(createCounter("system.network.dropped", "{packets}"), ""))
+}
+
+func TestBrokenUnit(t *testing.T) {
+	require.Equal(t, "system_network_dropped_packets", normalizeName(createGauge("system.network.dropped", "packets"), ""))
+	require.Equal(t, "system_network_packets_dropped", normalizeName(createGauge("system.network.packets.dropped", "packets"), ""))
+	require.Equal(t, "system_network_packets", normalizeName(createGauge("system.network.packets", "packets"), ""))
+}
+
+func TestBrokenUnitCounter(t *testing.T) {
+	require.Equal(t, "system_network_dropped_packets_total", normalizeName(createCounter("system.network.dropped", "packets"), ""))
+	require.Equal(t, "system_network_packets_dropped_total", normalizeName(createCounter("system.network.packets.dropped", "packets"), ""))
+	require.Equal(t, "system_network_packets_total", normalizeName(createCounter("system.network.packets", "packets"), ""))
+}
+
+func TestRatio(t *testing.T) {
+	require.Equal(t, "hw_gpu_memory_utilization_ratio", normalizeName(createGauge("hw.gpu.memory.utilization", "1"), ""))
+	require.Equal(t, "hw_fan_speed_ratio", normalizeName(createGauge("hw.fan.speed_ratio", "1"), ""))
+	require.Equal(t, "objects_total", normalizeName(createCounter("objects", "1"), ""))
+}
+
+func TestHertz(t *testing.T) {
+	require.Equal(t, "hw_cpu_speed_limit_hertz", normalizeName(createGauge("hw.cpu.speed_limit", "Hz"), ""))
+}
+
+func TestPer(t *testing.T) {
+	require.Equal(t, "broken_metric_speed_km_per_hour", normalizeName(createGauge("broken.metric.speed", "km/h"), ""))
+	require.Equal(t, "astro_light_speed_limit_meters_per_second", normalizeName(createGauge("astro.light.speed_limit", "m/s"), ""))
+}
+
+func TestPercent(t *testing.T) {
+	require.Equal(t, "broken_metric_success_ratio_percent", normalizeName(createGauge("broken.metric.success_ratio", "%"), ""))
+	require.Equal(t, "broken_metric_success_percent", normalizeName(createGauge("broken.metric.success_percent", "%"), ""))
+}
+
+func TestEmpty(t *testing.T) {
+	require.Equal(t, "test_metric_no_unit", normalizeName(createGauge("test.metric.no_unit", ""), ""))
+	require.Equal(t, "test_metric_spaces", normalizeName(createGauge("test.metric.spaces", "   \t  "), ""))
+}
+
+func TestUnsupportedRunes(t *testing.T) {
+	require.Equal(t, "unsupported_metric_temperature_F", normalizeName(createGauge("unsupported.metric.temperature", "°F"), ""))
+	require.Equal(t, "unsupported_metric_weird", normalizeName(createGauge("unsupported.metric.weird", "+=.:,!* & #"), ""))
+	require.Equal(t, "unsupported_metric_redundant_test_per_C", normalizeName(createGauge("unsupported.metric.redundant", "__test $/°C"), ""))
+}
+
+func TestOTelReceivers(t *testing.T) {
+	require.Equal(t, "active_directory_ds_replication_network_io_bytes_total", normalizeName(createCounter("active_directory.ds.replication.network.io", "By"), ""))
+	require.Equal(t, "active_directory_ds_replication_sync_object_pending_total", normalizeName(createCounter("active_directory.ds.replication.sync.object.pending", "{objects}"), ""))
+	require.Equal(t, "active_directory_ds_replication_object_rate_per_second", normalizeName(createGauge("active_directory.ds.replication.object.rate", "{objects}/s"), ""))
+	require.Equal(t, "active_directory_ds_name_cache_hit_rate_percent", normalizeName(createGauge("active_directory.ds.name_cache.hit_rate", "%"), ""))
+	require.Equal(t, "active_directory_ds_ldap_bind_last_successful_time_milliseconds", normalizeName(createGauge("active_directory.ds.ldap.bind.last_successful.time", "ms"), ""))
+	require.Equal(t, "apache_current_connections", normalizeName(createGauge("apache.current_connections", "connections"), ""))
+	require.Equal(t, "apache_workers_connections", normalizeName(createGauge("apache.workers", "connections"), ""))
+	require.Equal(t, "apache_requests_total", normalizeName(createCounter("apache.requests", "1"), ""))
+	require.Equal(t, "bigip_virtual_server_request_count_total", normalizeName(createCounter("bigip.virtual_server.request.count", "{requests}"), ""))
+	require.Equal(t, "system_cpu_utilization_ratio", normalizeName(createGauge("system.cpu.utilization", "1"), ""))
+	require.Equal(t, "system_disk_operation_time_seconds_total", normalizeName(createCounter("system.disk.operation_time", "s"), ""))
+	require.Equal(t, "system_cpu_load_average_15m_ratio", normalizeName(createGauge("system.cpu.load_average.15m", "1"), ""))
+	require.Equal(t, "memcached_operation_hit_ratio_percent", normalizeName(createGauge("memcached.operation_hit_ratio", "%"), ""))
+	require.Equal(t, "mongodbatlas_process_asserts_per_second", normalizeName(createGauge("mongodbatlas.process.asserts", "{assertions}/s"), ""))
+	require.Equal(t, "mongodbatlas_process_journaling_data_files_mebibytes", normalizeName(createGauge("mongodbatlas.process.journaling.data_files", "MiBy"), ""))
+	require.Equal(t, "mongodbatlas_process_network_io_bytes_per_second", normalizeName(createGauge("mongodbatlas.process.network.io", "By/s"), ""))
+	require.Equal(t, "mongodbatlas_process_oplog_rate_gibibytes_per_hour", normalizeName(createGauge("mongodbatlas.process.oplog.rate", "GiBy/h"), ""))
+	require.Equal(t, "mongodbatlas_process_db_query_targeting_scanned_per_returned", normalizeName(createGauge("mongodbatlas.process.db.query_targeting.scanned_per_returned", "{scanned}/{returned}"), ""))
+	require.Equal(t, "nginx_requests", normalizeName(createGauge("nginx.requests", "requests"), ""))
+	require.Equal(t, "nginx_connections_accepted", normalizeName(createGauge("nginx.connections_accepted", "connections"), ""))
+	require.Equal(t, "nsxt_node_memory_usage_kilobytes", normalizeName(createGauge("nsxt.node.memory.usage", "KBy"), ""))
+	require.Equal(t, "redis_latest_fork_microseconds", normalizeName(createGauge("redis.latest_fork", "us"), ""))
+}
+
+func TestTrimPromSuffixes(t *testing.T) {
+	assert.Equal(t, "active_directory_ds_replication_network_io", TrimPromSuffixes("active_directory_ds_replication_network_io_bytes_total", pmetric.MetricTypeSum, "bytes"))
+	assert.Equal(t, "active_directory_ds_name_cache_hit_rate", TrimPromSuffixes("active_directory_ds_name_cache_hit_rate_percent", pmetric.MetricTypeGauge, "percent"))
+	assert.Equal(t, "active_directory_ds_ldap_bind_last_successful_time", TrimPromSuffixes("active_directory_ds_ldap_bind_last_successful_time_milliseconds", pmetric.MetricTypeGauge, "milliseconds"))
+	assert.Equal(t, "apache_requests", TrimPromSuffixes("apache_requests_total", pmetric.MetricTypeSum, "1"))
+	assert.Equal(t, "system_cpu_utilization", TrimPromSuffixes("system_cpu_utilization_ratio", pmetric.MetricTypeGauge, "ratio"))
+	assert.Equal(t, "mongodbatlas_process_journaling_data_files", TrimPromSuffixes("mongodbatlas_process_journaling_data_files_mebibytes", pmetric.MetricTypeGauge, "mebibytes"))
+	assert.Equal(t, "mongodbatlas_process_network_io", TrimPromSuffixes("mongodbatlas_process_network_io_bytes_per_second", pmetric.MetricTypeGauge, "bytes_per_second"))
+	assert.Equal(t, "mongodbatlas_process_oplog_rate", TrimPromSuffixes("mongodbatlas_process_oplog_rate_gibibytes_per_hour", pmetric.MetricTypeGauge, "gibibytes_per_hour"))
+	assert.Equal(t, "nsxt_node_memory_usage", TrimPromSuffixes("nsxt_node_memory_usage_kilobytes", pmetric.MetricTypeGauge, "kilobytes"))
+	assert.Equal(t, "redis_latest_fork", TrimPromSuffixes("redis_latest_fork_microseconds", pmetric.MetricTypeGauge, "microseconds"))
+	assert.Equal(t, "up", TrimPromSuffixes("up", pmetric.MetricTypeGauge, ""))
+
+	// These are not necessarily valid OM units, only tested for the sake of completeness.
+	assert.Equal(t, "active_directory_ds_replication_sync_object_pending", TrimPromSuffixes("active_directory_ds_replication_sync_object_pending_total", pmetric.MetricTypeSum, "{objects}"))
+	assert.Equal(t, "apache_current", TrimPromSuffixes("apache_current_connections", pmetric.MetricTypeGauge, "connections"))
+	assert.Equal(t, "bigip_virtual_server_request_count", TrimPromSuffixes("bigip_virtual_server_request_count_total", pmetric.MetricTypeSum, "{requests}"))
+	assert.Equal(t, "mongodbatlas_process_db_query_targeting_scanned_per_returned", TrimPromSuffixes("mongodbatlas_process_db_query_targeting_scanned_per_returned", pmetric.MetricTypeGauge, "{scanned}/{returned}"))
+	assert.Equal(t, "nginx_connections_accepted", TrimPromSuffixes("nginx_connections_accepted", pmetric.MetricTypeGauge, "connections"))
+	assert.Equal(t, "apache_workers", TrimPromSuffixes("apache_workers_connections", pmetric.MetricTypeGauge, "connections"))
+	assert.Equal(t, "nginx", TrimPromSuffixes("nginx_requests", pmetric.MetricTypeGauge, "requests"))
+
+	// Units shouldn't be trimmed if the unit is not a direct match with the suffix, i.e, a suffix "_seconds" shouldn't be removed if unit is "sec" or "s"
+	assert.Equal(t, "system_cpu_load_average_15m_ratio", TrimPromSuffixes("system_cpu_load_average_15m_ratio", pmetric.MetricTypeGauge, "1"))
+	assert.Equal(t, "mongodbatlas_process_asserts_per_second", TrimPromSuffixes("mongodbatlas_process_asserts_per_second", pmetric.MetricTypeGauge, "{assertions}/s"))
+	assert.Equal(t, "memcached_operation_hit_ratio_percent", TrimPromSuffixes("memcached_operation_hit_ratio_percent", pmetric.MetricTypeGauge, "%"))
+	assert.Equal(t, "active_directory_ds_replication_object_rate_per_second", TrimPromSuffixes("active_directory_ds_replication_object_rate_per_second", pmetric.MetricTypeGauge, "{objects}/s"))
+	assert.Equal(t, "system_disk_operation_time_seconds", TrimPromSuffixes("system_disk_operation_time_seconds_total", pmetric.MetricTypeSum, "s"))
+}
+
+func TestNamespace(t *testing.T) {
+	require.Equal(t, "space_test", normalizeName(createGauge("test", ""), "space"))
+	require.Equal(t, "space_test", normalizeName(createGauge("#test", ""), "space"))
+}
+
+func TestCleanUpString(t *testing.T) {
+	require.Equal(t, "", CleanUpString(""))
+	require.Equal(t, "a_b", CleanUpString("a b"))
+	require.Equal(t, "hello_world", CleanUpString("hello, world!"))
+	require.Equal(t, "hello_you_2", CleanUpString("hello you 2"))
+	require.Equal(t, "1000", CleanUpString("$1000"))
+	require.Equal(t, "", CleanUpString("*+$^=)"))
+}
+
+func TestUnitMapGetOrDefault(t *testing.T) {
+	require.Equal(t, "", unitMapGetOrDefault(""))
+	require.Equal(t, "seconds", unitMapGetOrDefault("s"))
+	require.Equal(t, "invalid", unitMapGetOrDefault("invalid"))
+}
+
+func TestPerUnitMapGetOrDefault(t *testing.T) {
+	require.Equal(t, "", perUnitMapGetOrDefault(""))
+	require.Equal(t, "second", perUnitMapGetOrDefault("s"))
+	require.Equal(t, "invalid", perUnitMapGetOrDefault("invalid"))
+}
+
+func TestRemoveItem(t *testing.T) {
+	require.Equal(t, []string{}, removeItem([]string{}, "test"))
+	require.Equal(t, []string{}, removeItem([]string{}, ""))
+	require.Equal(t, []string{"a", "b", "c"}, removeItem([]string{"a", "b", "c"}, "d"))
+	require.Equal(t, []string{"a", "b", "c"}, removeItem([]string{"a", "b", "c"}, ""))
+	require.Equal(t, []string{"a", "b"}, removeItem([]string{"a", "b", "c"}, "c"))
+	require.Equal(t, []string{"a", "c"}, removeItem([]string{"a", "b", "c"}, "b"))
+	require.Equal(t, []string{"b", "c"}, removeItem([]string{"a", "b", "c"}, "a"))
+}
+
+func TestBuildCompliantNameWithNormalize(t *testing.T) {
+	require.Equal(t, "system_io_bytes_total", BuildCompliantName(createCounter("system.io", "By"), "", true))
+	require.Equal(t, "system_network_io_bytes_total", BuildCompliantName(createCounter("network.io", "By"), "system", true))
+	require.Equal(t, "_3_14_digits", BuildCompliantName(createGauge("3.14 digits", ""), "", true))
+	require.Equal(t, "envoy_rule_engine_zlib_buf_error", BuildCompliantName(createGauge("envoy__rule_engine_zlib_buf_error", ""), "", true))
+	require.Equal(t, "foo_bar", BuildCompliantName(createGauge(":foo::bar", ""), "", true))
+	require.Equal(t, "foo_bar_total", BuildCompliantName(createCounter(":foo::bar", ""), "", true))
+	// Gauges with unit 1 are considered ratios.
+	require.Equal(t, "foo_bar_ratio", BuildCompliantName(createGauge("foo.bar", "1"), "", true))
+	// Slashes in units are converted.
+	require.Equal(t, "system_io_foo_per_bar_total", BuildCompliantName(createCounter("system.io", "foo/bar"), "", true))
+}
+
+func TestBuildCompliantNameWithoutSuffixes(t *testing.T) {
+	require.Equal(t, "system_io", BuildCompliantName(createCounter("system.io", "By"), "", false))
+	require.Equal(t, "system_network_io", BuildCompliantName(createCounter("network.io", "By"), "system", false))
+	require.Equal(t, "system_network_I_O", BuildCompliantName(createCounter("network (I/O)", "By"), "system", false))
+	require.Equal(t, "_3_14_digits", BuildCompliantName(createGauge("3.14 digits", "By"), "", false))
+	require.Equal(t, "envoy__rule_engine_zlib_buf_error", BuildCompliantName(createGauge("envoy__rule_engine_zlib_buf_error", ""), "", false))
+	require.Equal(t, ":foo::bar", BuildCompliantName(createGauge(":foo::bar", ""), "", false))
+	require.Equal(t, ":foo::bar", BuildCompliantName(createCounter(":foo::bar", ""), "", false))
+}
diff --git a/storage/remote/otlptranslator/prometheus/testutils_test.go b/storage/remote/otlptranslator/prometheus/testutils_test.go
new file mode 100644
index 0000000000..363328c571
--- /dev/null
+++ b/storage/remote/otlptranslator/prometheus/testutils_test.go
@@ -0,0 +1,49 @@
+// Copyright 2024 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+// Provenance-includes-location: https://github.com/open-telemetry/opentelemetry-collector-contrib/blob/95e8f8fdc2a9dc87230406c9a3cf02be4fd68bea/pkg/translator/prometheus/testutils_test.go
+// Provenance-includes-license: Apache-2.0
+// Provenance-includes-copyright: Copyright The OpenTelemetry Authors.
+
+package prometheus
+
+import (
+	"go.opentelemetry.io/collector/pdata/pmetric"
+)
+
+var ilm pmetric.ScopeMetrics
+
+func init() {
+
+	metrics := pmetric.NewMetrics()
+	resourceMetrics := metrics.ResourceMetrics().AppendEmpty()
+	ilm = resourceMetrics.ScopeMetrics().AppendEmpty()
+
+}
+
+// Returns a new Metric of type "Gauge" with specified name and unit
+func createGauge(name string, unit string) pmetric.Metric {
+	gauge := ilm.Metrics().AppendEmpty()
+	gauge.SetName(name)
+	gauge.SetUnit(unit)
+	gauge.SetEmptyGauge()
+	return gauge
+}
+
+// Returns a new Metric of type Monotonic Sum with specified name and unit
+func createCounter(name string, unit string) pmetric.Metric {
+	counter := ilm.Metrics().AppendEmpty()
+	counter.SetEmptySum().SetIsMonotonic(true)
+	counter.SetName(name)
+	counter.SetUnit(unit)
+	return counter
+}

From 4fb2183437728b5107b27323ff1520de0fa21203 Mon Sep 17 00:00:00 2001
From: Arve Knudsen <arve.knudsen@gmail.com>
Date: Fri, 26 Jul 2024 11:21:58 +0200
Subject: [PATCH 03/12] Test a couple more cases without suffix gen

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
---
 storage/remote/otlptranslator/prometheus/normalize_name_test.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/storage/remote/otlptranslator/prometheus/normalize_name_test.go b/storage/remote/otlptranslator/prometheus/normalize_name_test.go
index ee25bb2dff..07b9b0a784 100644
--- a/storage/remote/otlptranslator/prometheus/normalize_name_test.go
+++ b/storage/remote/otlptranslator/prometheus/normalize_name_test.go
@@ -200,4 +200,6 @@ func TestBuildCompliantNameWithoutSuffixes(t *testing.T) {
 	require.Equal(t, "envoy__rule_engine_zlib_buf_error", BuildCompliantName(createGauge("envoy__rule_engine_zlib_buf_error", ""), "", false))
 	require.Equal(t, ":foo::bar", BuildCompliantName(createGauge(":foo::bar", ""), "", false))
 	require.Equal(t, ":foo::bar", BuildCompliantName(createCounter(":foo::bar", ""), "", false))
+	require.Equal(t, "foo_bar", BuildCompliantName(createGauge("foo.bar", "1"), "", false))
+	require.Equal(t, "system_io", BuildCompliantName(createCounter("system.io", "foo/bar"), "", false))
 }

From 9bc42f4400d2be308054f91b14a1402b4485d0d0 Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Thu, 1 Aug 2024 23:46:33 +0000
Subject: [PATCH 04/12] build(deps): bump bufbuild/buf-setup-action from 1.34.0
 to 1.35.1

Bumps [bufbuild/buf-setup-action](https://github.com/bufbuild/buf-setup-action) from 1.34.0 to 1.35.1.
- [Release notes](https://github.com/bufbuild/buf-setup-action/releases)
- [Commits](https://github.com/bufbuild/buf-setup-action/compare/35c243d7f2a909b1d4e40399b348a7fdab27d78d...aceb106d2419c4cff48863df90161d92decb8591)

---
updated-dependencies:
- dependency-name: bufbuild/buf-setup-action
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/buf-lint.yml | 2 +-
 .github/workflows/buf.yml      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/buf-lint.yml b/.github/workflows/buf-lint.yml
index cbfeb2ba5b..9f60a2336d 100644
--- a/.github/workflows/buf-lint.yml
+++ b/.github/workflows/buf-lint.yml
@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
-      - uses: bufbuild/buf-setup-action@35c243d7f2a909b1d4e40399b348a7fdab27d78d # v1.34.0
+      - uses: bufbuild/buf-setup-action@aceb106d2419c4cff48863df90161d92decb8591 # v1.35.1
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
       - uses: bufbuild/buf-lint-action@06f9dd823d873146471cfaaf108a993fe00e5325 # v1.1.1
diff --git a/.github/workflows/buf.yml b/.github/workflows/buf.yml
index 8b964ef24c..1856fb95e7 100644
--- a/.github/workflows/buf.yml
+++ b/.github/workflows/buf.yml
@@ -13,7 +13,7 @@ jobs:
     if: github.repository_owner == 'prometheus'
     steps:
       - uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29 # v4.1.6
-      - uses: bufbuild/buf-setup-action@35c243d7f2a909b1d4e40399b348a7fdab27d78d # v1.34.0
+      - uses: bufbuild/buf-setup-action@aceb106d2419c4cff48863df90161d92decb8591 # v1.35.1
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
       - uses: bufbuild/buf-lint-action@06f9dd823d873146471cfaaf108a993fe00e5325 # v1.1.1

From f6f911db751fb4011ff1298c43a5c5bf262df55f Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Thu, 1 Aug 2024 23:46:48 +0000
Subject: [PATCH 05/12] build(deps): bump actions/upload-artifact from 4.3.3 to
 4.3.4

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4.3.3 to 4.3.4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](https://github.com/actions/upload-artifact/compare/65462800fd760344b1a7b4382951275a0abb4808...0b2256b8c012f0828dc542b3febcab082c67f72b)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 .github/workflows/fuzzing.yml    | 2 +-
 .github/workflows/scorecards.yml | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/fuzzing.yml b/.github/workflows/fuzzing.yml
index dc510e5966..f3953cb2a4 100644
--- a/.github/workflows/fuzzing.yml
+++ b/.github/workflows/fuzzing.yml
@@ -21,7 +21,7 @@ jobs:
           fuzz-seconds: 600
           dry-run: false
       - name: Upload Crash
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # v4.3.3
+        uses: actions/upload-artifact@0b2256b8c012f0828dc542b3febcab082c67f72b # v4.3.4
         if: failure() && steps.build.outcome == 'success'
         with:
           name: artifacts
diff --git a/.github/workflows/scorecards.yml b/.github/workflows/scorecards.yml
index c82fa87a1e..6e16660ac5 100644
--- a/.github/workflows/scorecards.yml
+++ b/.github/workflows/scorecards.yml
@@ -37,7 +37,7 @@ jobs:
       # Upload the results as artifacts (optional). Commenting out will disable uploads of run results in SARIF
       # format to the repository Actions tab.
       - name: "Upload artifact"
-        uses: actions/upload-artifact@65462800fd760344b1a7b4382951275a0abb4808 # tag=v4.3.3
+        uses: actions/upload-artifact@0b2256b8c012f0828dc542b3febcab082c67f72b # tag=v4.3.4
         with:
           name: SARIF file
           path: results.sarif

From 4553d1baa62da853e7e6e4841f9a376af47b327e Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Thu, 1 Aug 2024 23:54:21 +0000
Subject: [PATCH 06/12] build(deps): bump actions/setup-go from 5.0.1 to 5.0.2
 in /scripts

Bumps [actions/setup-go](https://github.com/actions/setup-go) from 5.0.1 to 5.0.2.
- [Release notes](https://github.com/actions/setup-go/releases)
- [Commits](https://github.com/actions/setup-go/compare/cdcb36043654635271a94b9a6d1392de5bb323a7...0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32)

---
updated-dependencies:
- dependency-name: actions/setup-go
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 scripts/golangci-lint.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/golangci-lint.yml b/scripts/golangci-lint.yml
index 83ae3906cc..90e3ed79a2 100644
--- a/scripts/golangci-lint.yml
+++ b/scripts/golangci-lint.yml
@@ -26,7 +26,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4.1.7
       - name: Install Go
-        uses: actions/setup-go@cdcb36043654635271a94b9a6d1392de5bb323a7 # v5.0.1
+        uses: actions/setup-go@0a12ed9d6a96ab950c8f026ed9f722fe0da7ef32 # v5.0.2
         with:
           go-version: 1.22.x
       - name: Install snmp_exporter/generator dependencies

From 6900bf48d06837e3a79ef31829565721eca84cbe Mon Sep 17 00:00:00 2001
From: "dependabot[bot]" <49699333+dependabot[bot]@users.noreply.github.com>
Date: Tue, 6 Aug 2024 13:55:03 +0000
Subject: [PATCH 07/12] build(deps): bump github.com/aws/aws-sdk-go from
 1.54.19 to 1.55.5

Bumps [github.com/aws/aws-sdk-go](https://github.com/aws/aws-sdk-go) from 1.54.19 to 1.55.5.
- [Release notes](https://github.com/aws/aws-sdk-go/releases)
- [Commits](https://github.com/aws/aws-sdk-go/compare/v1.54.19...v1.55.5)

---
updated-dependencies:
- dependency-name: github.com/aws/aws-sdk-go
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
---
 go.mod | 2 +-
 go.sum | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/go.mod b/go.mod
index 138e1bae93..02844cd8a5 100644
--- a/go.mod
+++ b/go.mod
@@ -13,7 +13,7 @@ require (
 	github.com/KimMachineGun/automemlimit v0.6.1
 	github.com/alecthomas/kingpin/v2 v2.4.0
 	github.com/alecthomas/units v0.0.0-20240626203959-61d1e3462e30
-	github.com/aws/aws-sdk-go v1.54.19
+	github.com/aws/aws-sdk-go v1.55.5
 	github.com/bboreham/go-loser v0.0.0-20230920113527-fcc2c21820a3
 	github.com/cespare/xxhash/v2 v2.3.0
 	github.com/dennwc/varint v1.0.0
diff --git a/go.sum b/go.sum
index fb5c1772ae..9841b54289 100644
--- a/go.sum
+++ b/go.sum
@@ -92,8 +92,8 @@ github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2/go.mod h1:W
 github.com/aws/aws-lambda-go v1.13.3/go.mod h1:4UKl9IzQMoD+QF79YdCuzCwp8VbmG4VAQwij/eHl5CU=
 github.com/aws/aws-sdk-go v1.27.0/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
 github.com/aws/aws-sdk-go v1.38.35/go.mod h1:hcU610XS61/+aQV88ixoOzUoG7v3b31pl2zKMmprdro=
-github.com/aws/aws-sdk-go v1.54.19 h1:tyWV+07jagrNiCcGRzRhdtVjQs7Vy41NwsuOcl0IbVI=
-github.com/aws/aws-sdk-go v1.54.19/go.mod h1:eRwEWoyTWFMVYVQzKMNHWP5/RV4xIUGMQfXQHfHkpNU=
+github.com/aws/aws-sdk-go v1.55.5 h1:KKUZBfBoyqy5d3swXyiC7Q76ic40rYcbqH7qjh59kzU=
+github.com/aws/aws-sdk-go v1.55.5/go.mod h1:eRwEWoyTWFMVYVQzKMNHWP5/RV4xIUGMQfXQHfHkpNU=
 github.com/aws/aws-sdk-go-v2 v0.18.0/go.mod h1:JWVYvqSMppoMJC0x5wdwiImzgXTI9FuZwxzkQq9wy+g=
 github.com/bboreham/go-loser v0.0.0-20230920113527-fcc2c21820a3 h1:6df1vn4bBlDDo4tARvBm7l6KA9iVMnE3NWizDeWSrps=
 github.com/bboreham/go-loser v0.0.0-20230920113527-fcc2c21820a3/go.mod h1:CIWtjkly68+yqLPbvwwR/fjNJA/idrtULjZWh2v1ys0=

From f91009aa2ef0721ec41870d7b1ae4c44876801cb Mon Sep 17 00:00:00 2001
From: Charles Korn <charles.korn@grafana.com>
Date: Thu, 8 Aug 2024 09:11:38 +1000
Subject: [PATCH 08/12] promql: clarify error message when panic occurs during
 query evaluation

Signed-off-by: Charles Korn <charles.korn@grafana.com>
---
 promql/engine.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/promql/engine.go b/promql/engine.go
index 1427302e5e..102987d737 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -1057,7 +1057,7 @@ func (ev *evaluator) recover(expr parser.Expr, ws *annotations.Annotations, errp
 		buf := make([]byte, 64<<10)
 		buf = buf[:runtime.Stack(buf, false)]
 
-		level.Error(ev.logger).Log("msg", "runtime panic in parser", "expr", expr.String(), "err", e, "stacktrace", string(buf))
+		level.Error(ev.logger).Log("msg", "runtime panic during query evaluation", "expr", expr.String(), "err", e, "stacktrace", string(buf))
 		*errp = fmt.Errorf("unexpected error: %w", err)
 	case errWithWarnings:
 		*errp = err.err

From 06a8886b94e18c65fe682da1a66c0172f8236494 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gy=C3=B6rgy=20Krajcsovits?= <gyorgy.krajcsovits@grafana.com>
Date: Mon, 12 Aug 2024 10:39:08 +0200
Subject: [PATCH 09/12] Native histograms: define behavior when rate is null.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Histogram quantile returns NaN in this case, which might be
surprising, so add a unit test that clarifies that this is
intentional.

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
---
 promql/promqltest/testdata/histograms.test    | 29 ++++++++++++++
 .../testdata/native_histograms.test           | 39 +++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/promql/promqltest/testdata/histograms.test b/promql/promqltest/testdata/histograms.test
index 349a1e79c0..ef3ca00789 100644
--- a/promql/promqltest/testdata/histograms.test
+++ b/promql/promqltest/testdata/histograms.test
@@ -482,3 +482,32 @@ load_with_nhcb 5m
 eval_fail instant at 50m histogram_quantile(0.99, {__name__=~"request_duration_seconds\\d*_bucket"})
 
 eval_fail instant at 50m histogram_quantile(0.99, {__name__=~"request_duration_seconds\\d*"})
+
+# Histogram with constant buckets.
+load_with_nhcb 1m
+    const_histogram_bucket{le="0.0"} 1 1 1 1 1
+    const_histogram_bucket{le="1.0"} 1 1 1 1 1
+    const_histogram_bucket{le="2.0"} 1 1 1 1 1
+    const_histogram_bucket{le="+Inf"} 1 1 1 1 1
+
+# There is no change to the bucket count over time, thus rate is 0 in each bucket.
+eval instant at 5m rate(const_histogram_bucket[5m])
+    {le="0.0"} 0
+    {le="1.0"} 0
+    {le="2.0"} 0
+    {le="+Inf"} 0
+
+# There is no change to the bucket count over time, thus rate is 0 in each bucket.
+# However native histograms do not represent empty buckets, so here the zeros are implicit.
+eval instant at 5m rate(const_histogram[5m])
+    {} {{schema:-53 sum:0 count:0 custom_values:[0.0 1.0 2.0]}}
+
+# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# which means that any quantile is a NaN.
+eval instant at 5m histogram_quantile(1.0, sum by (le) (rate(const_histogram_bucket[5m])))
+    {} NaN
+
+# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# which means that any quantile is a NaN.
+eval instant at 5m histogram_quantile(1.0, sum(rate(const_histogram[5m])))
+    {} NaN
diff --git a/promql/promqltest/testdata/native_histograms.test b/promql/promqltest/testdata/native_histograms.test
index f91626c34e..a9ac0303c4 100644
--- a/promql/promqltest/testdata/native_histograms.test
+++ b/promql/promqltest/testdata/native_histograms.test
@@ -784,3 +784,42 @@ eval_warn instant at 1m rate(some_metric[30s])
 # Start with exponential, end with custom.
 eval_warn instant at 30s rate(some_metric[30s])
     # Should produce no results.
+
+# Histogram with constant buckets.
+load 1m
+    const_histogram {{schema:0 sum:1 count:1 buckets:[1 1 1]}} {{schema:0 sum:1 count:1 buckets:[1 1 1]}} {{schema:0 sum:1 count:1 buckets:[1 1 1]}} {{schema:0 sum:1 count:1 buckets:[1 1 1]}} {{schema:0 sum:1 count:1 buckets:[1 1 1]}}
+
+# There is no change to the bucket count over time, thus rate is 0 in each bucket.
+# However native histograms do not represent empty buckets, so here the zeros are implicit.
+eval instant at 5m rate(const_histogram[5m])
+    {} {{schema:0 sum:0 count:0}}
+
+# Zero buckets mean no observations, so average has no meaningful value.
+eval instant at 5m histogram_avg(rate(const_histogram[5m]))
+    {} NaN
+
+# Zero buckets mean no observations, so count is 0.
+eval instant at 5m histogram_count(rate(const_histogram[5m]))
+    {} 0.0
+
+# Zero buckets mean no observations, so the sum should be NaN, However
+# we return 0 for compatibility with classic histograms.
+eval instant at 5m histogram_sum(rate(const_histogram[5m]))
+    {} 0.0
+
+# BUG??? Zero buckets mean no observations, thus any fraction should be 0.
+eval instant at 5m histogram_fraction(0.0, 1.0, rate(const_histogram[5m]))
+    {} NaN
+
+# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# which means that any quantile is a NaN.
+eval instant at 5m histogram_quantile(1.0, rate(const_histogram[5m]))
+    {} NaN
+
+# Zero buckets mean no observations, so there is no standard deviation.
+eval instant at 5m histogram_stddev(rate(const_histogram[5m]))
+    {} NaN
+
+# Zero buckets mean no observations, so there is no standard variance.
+eval instant at 5m histogram_stdvar(rate(const_histogram[5m]))
+    {} NaN

From 6aee5b4b38fb2653dc1a93eda960f24de56f1305 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gy=C3=B6rgy=20Krajcsovits?= <gyorgy.krajcsovits@grafana.com>
Date: Mon, 12 Aug 2024 12:04:45 +0200
Subject: [PATCH 10/12] fix typo
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
---
 promql/promqltest/testdata/histograms.test        | 4 ++--
 promql/promqltest/testdata/native_histograms.test | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/promql/promqltest/testdata/histograms.test b/promql/promqltest/testdata/histograms.test
index ef3ca00789..70df9434e6 100644
--- a/promql/promqltest/testdata/histograms.test
+++ b/promql/promqltest/testdata/histograms.test
@@ -502,12 +502,12 @@ eval instant at 5m rate(const_histogram_bucket[5m])
 eval instant at 5m rate(const_histogram[5m])
     {} {{schema:-53 sum:0 count:0 custom_values:[0.0 1.0 2.0]}}
 
-# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# Zero buckets mean no observations, so there is no value that observations fall below,
 # which means that any quantile is a NaN.
 eval instant at 5m histogram_quantile(1.0, sum by (le) (rate(const_histogram_bucket[5m])))
     {} NaN
 
-# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# Zero buckets mean no observations, so there is no value that observations fall below,
 # which means that any quantile is a NaN.
 eval instant at 5m histogram_quantile(1.0, sum(rate(const_histogram[5m])))
     {} NaN
diff --git a/promql/promqltest/testdata/native_histograms.test b/promql/promqltest/testdata/native_histograms.test
index a9ac0303c4..948e15806c 100644
--- a/promql/promqltest/testdata/native_histograms.test
+++ b/promql/promqltest/testdata/native_histograms.test
@@ -811,7 +811,7 @@ eval instant at 5m histogram_sum(rate(const_histogram[5m]))
 eval instant at 5m histogram_fraction(0.0, 1.0, rate(const_histogram[5m]))
     {} NaN
 
-# Zero buckets mean no observations, so there is no value that observations fall bellow,
+# Zero buckets mean no observations, so there is no value that observations fall below,
 # which means that any quantile is a NaN.
 eval instant at 5m histogram_quantile(1.0, rate(const_histogram[5m]))
     {} NaN

From 0503d4f3722621904bf095fb0d4805b68e3066d5 Mon Sep 17 00:00:00 2001
From: Arve Knudsen <arve.knudsen@gmail.com>
Date: Tue, 13 Aug 2024 08:55:24 +0200
Subject: [PATCH 11/12] PromQL: Fix comment regarding non-nil histogram pointer

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
---
 promql/engine.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/promql/engine.go b/promql/engine.go
index 1427302e5e..30af001d39 100644
--- a/promql/engine.go
+++ b/promql/engine.go
@@ -2357,7 +2357,7 @@ loop:
 			histograms = append(histograms, HPoint{H: &histogram.FloatHistogram{}})
 		}
 		if histograms[n].H == nil {
-			// Make sure to pass non zero H to AtFloatHistogram so that it does a deep-copy.
+			// Make sure to pass non-nil H to AtFloatHistogram so that it does a deep-copy.
 			// Not an issue in the loop above since that uses an intermediate buffer.
 			histograms[n].H = &histogram.FloatHistogram{}
 		}

From 386fc8b9f69c0ac5ca81273a145ced408ea9d6d1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Gy=C3=B6rgy=20Krajcsovits?= <gyorgy.krajcsovits@grafana.com>
Date: Tue, 13 Aug 2024 15:26:07 +0200
Subject: [PATCH 12/12] Update from review comments.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: György Krajcsovits <gyorgy.krajcsovits@grafana.com>
---
 promql/promqltest/testdata/histograms.test        |  5 +----
 promql/promqltest/testdata/native_histograms.test | 13 +++++++++----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/promql/promqltest/testdata/histograms.test b/promql/promqltest/testdata/histograms.test
index 70df9434e6..47cba79935 100644
--- a/promql/promqltest/testdata/histograms.test
+++ b/promql/promqltest/testdata/histograms.test
@@ -497,8 +497,7 @@ eval instant at 5m rate(const_histogram_bucket[5m])
     {le="2.0"} 0
     {le="+Inf"} 0
 
-# There is no change to the bucket count over time, thus rate is 0 in each bucket.
-# However native histograms do not represent empty buckets, so here the zeros are implicit.
+# Native histograms do not represent empty buckets, so here the zeros are implicit.
 eval instant at 5m rate(const_histogram[5m])
     {} {{schema:-53 sum:0 count:0 custom_values:[0.0 1.0 2.0]}}
 
@@ -507,7 +506,5 @@ eval instant at 5m rate(const_histogram[5m])
 eval instant at 5m histogram_quantile(1.0, sum by (le) (rate(const_histogram_bucket[5m])))
     {} NaN
 
-# Zero buckets mean no observations, so there is no value that observations fall below,
-# which means that any quantile is a NaN.
 eval instant at 5m histogram_quantile(1.0, sum(rate(const_histogram[5m])))
     {} NaN
diff --git a/promql/promqltest/testdata/native_histograms.test b/promql/promqltest/testdata/native_histograms.test
index 948e15806c..c2a5012e96 100644
--- a/promql/promqltest/testdata/native_histograms.test
+++ b/promql/promqltest/testdata/native_histograms.test
@@ -794,7 +794,8 @@ load 1m
 eval instant at 5m rate(const_histogram[5m])
     {} {{schema:0 sum:0 count:0}}
 
-# Zero buckets mean no observations, so average has no meaningful value.
+# Zero buckets mean no observations, thus the denominator in the average is 0
+# leading to 0/0, which is NaN.
 eval instant at 5m histogram_avg(rate(const_histogram[5m]))
     {} NaN
 
@@ -802,15 +803,19 @@ eval instant at 5m histogram_avg(rate(const_histogram[5m]))
 eval instant at 5m histogram_count(rate(const_histogram[5m]))
     {} 0.0
 
-# Zero buckets mean no observations, so the sum should be NaN, However
-# we return 0 for compatibility with classic histograms.
+# Zero buckets mean no observations and empty histogram has a sum of 0 by definition.
 eval instant at 5m histogram_sum(rate(const_histogram[5m]))
     {} 0.0
 
-# BUG??? Zero buckets mean no observations, thus any fraction should be 0.
+# Zero buckets mean no observations, thus the denominator in the fraction is 0,
+# leading to 0/0, which is NaN.
 eval instant at 5m histogram_fraction(0.0, 1.0, rate(const_histogram[5m]))
     {} NaN
 
+# Workaround to calculate the observation count corresponding to NaN fraction.
+eval instant at 5m histogram_count(rate(const_histogram[5m])) == 0.0 or histogram_fraction(0.0, 1.0, rate(const_histogram[5m])) * histogram_count(rate(const_histogram[5m]))
+    {} 0.0
+
 # Zero buckets mean no observations, so there is no value that observations fall below,
 # which means that any quantile is a NaN.
 eval instant at 5m histogram_quantile(1.0, rate(const_histogram[5m]))