Pebble: bump Pebble version and update to support the new Metrics.WALMetrics

DEPS.bzl

@@ -1754,10 +1754,10 @@ def go_deps():
         patches = [
             "@com_github_cockroachdb_cockroach//build/patches:com_github_cockroachdb_crlib.patch",
         ],
-        sha256 = "a9a4b8810d52a2d18dddbbc359d060f5db854e328b4d75f12b7c5081ac25b2a2",
-        strip_prefix = "github.com/cockroachdb/[email protected]20251024155502-a2e0a212ef05",
+        sha256 = "fa361e52b072ce18ac1d103e2556851906477361b5fe688745d29b1efabff3cb",
+        strip_prefix = "github.com/cockroachdb/[email protected]20251122031428-fe658a2dbda1",
         urls = [
-            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251024155502-a2e0a212ef05.zip",
+            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251122031428-fe658a2dbda1.zip",
         ],
     )
     go_repository(
@@ -1834,10 +1834,10 @@ def go_deps():
         patches = [
             "@com_github_cockroachdb_cockroach//build/patches:com_github_cockroachdb_pebble.patch",
         ],
-        sha256 = "e70a40a057027337af8f5bc3758dc0b1bd30c81a96f7d42455856c16f08b6309",
-        strip_prefix = "github.com/cockroachdb/[email protected]20251119182253-219f3fc13027",
+        sha256 = "402e2c8db1b570e5ea8395779f08dffcb30b8615e2f5bef6ba0de6d469810dd4",
+        strip_prefix = "github.com/cockroachdb/[email protected]20251124213414-e6b971f9a96e",
         urls = [
-            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20251119182253-219f3fc13027.zip",
+            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20251124213414-e6b971f9a96e.zip",
         ],
     )
     go_repository(

build/bazelutil/distdir_files.bzl

@@ -342,7 +342,7 @@ DISTDIR_FILES = {
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/cmux/com_github_cockroachdb_cmux-v0.0.0-20250514152509-914d3bf9ec58.zip": "c1cf4cd99a1ad6a00f2ccd4188cbcf004cb0d56895670b2c171061ce564cd791",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/cockroach-go/v2/com_github_cockroachdb_cockroach_go_v2-v2.4.1.zip": "ba646db91152f3121a6812c7b74d12d8c0e126f7b4d3b927618b159692ceb424",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlfmt/com_github_cockroachdb_crlfmt-v0.0.0-20221214225007-b2fc5c302548.zip": "fedc01bdd6d964da0425d5eaac8efadc951e78e13f102292cc0774197f09ab63",
-    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251024155502-a2e0a212ef05.zip": "a9a4b8810d52a2d18dddbbc359d060f5db854e328b4d75f12b7c5081ac25b2a2",
+    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/crlib/com_github_cockroachdb_crlib-v0.0.0-20251122031428-fe658a2dbda1.zip": "fa361e52b072ce18ac1d103e2556851906477361b5fe688745d29b1efabff3cb",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/datadriven/com_github_cockroachdb_datadriven-v1.0.3-0.20251006155849-f84f9e519edd.zip": "a7ffcef0b264d9c28c36b2f9b737ff739542f472d7614938ae507e2da269f6c2",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/drpc/com_github_cockroachdb_drpc-v0.0.0-20250924114114-78d4e121902a.zip": "98b44a51f82873f93f77da80230212ab40f35044e8d38645cb1392ae03462f0b",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/errors/com_github_cockroachdb_errors-v1.12.1-0.20251010171200-64801262cd6f.zip": "4df66cc44791d4290071696abf179dc6df7b94b4cb5d29a20f39c6bf522c60ee",
@@ -352,7 +352,7 @@ DISTDIR_FILES = {
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/gostdlib/com_github_cockroachdb_gostdlib-v1.19.0.zip": "c4d516bcfe8c07b6fc09b8a9a07a95065b36c2855627cb3514e40c98f872b69e",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/logtags/com_github_cockroachdb_logtags-v0.0.0-20241215232642-bb51bb14a506.zip": "920068af09e3846d9ebb4e4a7787ff1dd10f3989c5f940ad861b0f6a9f824f6e",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/metamorphic/com_github_cockroachdb_metamorphic-v0.0.0-20231108215700-4ba948b56895.zip": "28c8cf42192951b69378cf537be5a9a43f2aeb35542908cc4fe5f689505853ea",
-    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20251119182253-219f3fc13027.zip": "e70a40a057027337af8f5bc3758dc0b1bd30c81a96f7d42455856c16f08b6309",
+    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/pebble/com_github_cockroachdb_pebble-v0.0.0-20251124213414-e6b971f9a96e.zip": "402e2c8db1b570e5ea8395779f08dffcb30b8615e2f5bef6ba0de6d469810dd4",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/redact/com_github_cockroachdb_redact-v1.1.6.zip": "018eccb5fb9ca52d43ec9eaf213539d01c1f2b94e0e822406ebfb2e9321ef6cf",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/returncheck/com_github_cockroachdb_returncheck-v0.0.0-20200612231554-92cdbca611dd.zip": "ce92ba4352deec995b1f2eecf16eba7f5d51f5aa245a1c362dfe24c83d31f82b",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/cockroachdb/stress/com_github_cockroachdb_stress-v0.0.0-20220803192808-1806698b1b7b.zip": "3fda531795c600daf25532a4f98be2a1335cd1e5e182c72789bca79f5f69fcc1",

docs/generated/metrics/metrics.yaml

@@ -10548,6 +10548,15 @@ layers:
       derivative: NONE
       how_to_use: If this value is greater than 100ms, it is an indication of a disk stall. To mitigate the effects of disk stalls, consider deploying your cluster with WAL failover configured. When WAL failover is configured, the more relevant metric is storage.wal.failover_write_and_sync.latency, as this metric reflects the fsync latency of the primary and/or the secondary WAL device.
       essential: true
+    - name: storage.wal.secondary.file_op.latency
+      exported_name: storage_wal_secondary_file_op_latency
+      description: The latency of file operations on the secondary Write-Ahead Log device.
+      y_axis_label: File Op Latency
+      type: HISTOGRAM
+      unit: NANOSECONDS
+      aggregation: AVG
+      derivative: NONE
+      how_to_use: Only populated when WAL failover is configured. This metric tracks file operation latency specifically on the secondary WAL device.
     - name: storage.write-stalls
       exported_name: storage_write_stalls
       description: Number of instances of intentional write stalls to backpressure incoming writes

go.mod

@@ -132,12 +132,12 @@ require (
 	github.com/cockroachdb/changefeedpb v0.0.0-20250818184245-aab9e65dff20
 	github.com/cockroachdb/cmux v0.0.0-20250514152509-914d3bf9ec58
 	github.com/cockroachdb/cockroach-go/v2 v2.4.1
-	github.com/cockroachdb/crlib v0.0.0-20251024155502-a2e0a212ef05
+	github.com/cockroachdb/crlib v0.0.0-20251122031428-fe658a2dbda1
 	github.com/cockroachdb/datadriven v1.0.3-0.20251006155849-f84f9e519edd
 	github.com/cockroachdb/errors v1.12.1-0.20251010171200-64801262cd6f
 	github.com/cockroachdb/gostdlib v1.19.0
 	github.com/cockroachdb/logtags v0.0.0-20241215232642-bb51bb14a506
-	github.com/cockroachdb/pebble v0.0.0-20251119182253-219f3fc13027
+	github.com/cockroachdb/pebble v0.0.0-20251124213414-e6b971f9a96e
 	github.com/cockroachdb/redact v1.1.6
 	github.com/cockroachdb/returncheck v0.0.0-20200612231554-92cdbca611dd
 	github.com/cockroachdb/tokenbucket v0.0.0-20250429170803-42689b6311bb

go.sum

@@ -550,8 +550,8 @@ github.com/cockroachdb/cockroach-go/v2 v2.4.1 h1:ACVT/zXsuK6waRPVYtDQpsM8pPA7IA/
 github.com/cockroachdb/cockroach-go/v2 v2.4.1/go.mod h1:9U179XbCx4qFWtNhc7BiWLPfuyMVQ7qdAhfrwLz1vH0=
 github.com/cockroachdb/crlfmt v0.0.0-20221214225007-b2fc5c302548 h1:i0bnjanlWAvM50wHMT7EFyxlt5HQusznWrkwl+HBIsU=
 github.com/cockroachdb/crlfmt v0.0.0-20221214225007-b2fc5c302548/go.mod h1:qtkxNlt5i3rrdirfJE/bQeW/IeLajKexErv7jEIV+Uc=
-github.com/cockroachdb/crlib v0.0.0-20251024155502-a2e0a212ef05 h1:7DV1UcpuwF78hKMC33w8ube+/wawG/57dT8Wo56+vUo=
-github.com/cockroachdb/crlib v0.0.0-20251024155502-a2e0a212ef05/go.mod h1:ae57yNis2F1FThSNdPdoXfiPOVi8G1TLreCBQYPOdqo=
+github.com/cockroachdb/crlib v0.0.0-20251122031428-fe658a2dbda1 h1:iX0YCYC5Jbt2/g7zNTP/QxhrV8Syp5kkzNiERKeN1uE=
+github.com/cockroachdb/crlib v0.0.0-20251122031428-fe658a2dbda1/go.mod h1:NjNuToN/FbhwH1cCyM9G4Rhtxx+ZaOgtoqFR+thng7w=
 github.com/cockroachdb/datadriven v0.0.0-20190809214429-80d97fb3cbaa/go.mod h1:zn76sxSg3SzpJ0PPJaLDCu+Bu0Lg3sKTORVIj19EIF8=
 github.com/cockroachdb/datadriven v1.0.2/go.mod h1:a9RdTaap04u637JoCzcUoIcDmvwSUtcUFtT/C3kJlTU=
 github.com/cockroachdb/datadriven v1.0.3-0.20251006155849-f84f9e519edd h1:vpWCe7VvdQbQ/9wGtlH3i+Oj+9OggKci3lsASL1ydvg=
@@ -572,8 +572,8 @@ github.com/cockroachdb/logtags v0.0.0-20241215232642-bb51bb14a506 h1:ASDL+UJcILM
 github.com/cockroachdb/logtags v0.0.0-20241215232642-bb51bb14a506/go.mod h1:Mw7HqKr2kdtu6aYGn3tPmAftiP3QPX63LdK/zcariIo=
 github.com/cockroachdb/metamorphic v0.0.0-20231108215700-4ba948b56895 h1:XANOgPYtvELQ/h4IrmPAohXqe2pWA8Bwhejr3VQoZsA=
 github.com/cockroachdb/metamorphic v0.0.0-20231108215700-4ba948b56895/go.mod h1:aPd7gM9ov9M8v32Yy5NJrDyOcD8z642dqs+F0CeNXfA=
-github.com/cockroachdb/pebble v0.0.0-20251119182253-219f3fc13027 h1:6Rb15Lct/OjpiK4IwuGunbcDXpB3CI8aXu1K8xopu6A=
-github.com/cockroachdb/pebble v0.0.0-20251119182253-219f3fc13027/go.mod h1:XCkfpLCGXq5/lUtsHapEvHih54DWRK/AqhWee96YHsU=
+github.com/cockroachdb/pebble v0.0.0-20251124213414-e6b971f9a96e h1:937aM14KDCRVKw+mRgM0bbNAxPha350pbTDvnrPUk5c=
+github.com/cockroachdb/pebble v0.0.0-20251124213414-e6b971f9a96e/go.mod h1:4p9u+hqtw8sRxiY5cNFWETymMf4brYGG90pS8MzlXmg=
 github.com/cockroachdb/redact v1.1.6 h1:zXJBwDZ84xJNlHl1rMyCojqyIxv+7YUpQiJLQ7n4314=
 github.com/cockroachdb/redact v1.1.6/go.mod h1:BVNblN9mBWFyMyqK1k3AAiSxhvhfK2oOZZ2lK+dpvRg=
 github.com/cockroachdb/returncheck v0.0.0-20200612231554-92cdbca611dd h1:KFOt5I9nEKZgCnOSmy8r4Oykh8BYQO8bFOTgHDS8YZA=

pkg/kv/kvserver/metrics.go

@@ -2842,6 +2842,9 @@ Note that the measurement does not include the duration for replicating the eval
 		Measurement: "Events",
 		Unit:        metric.Unit_COUNT,
 	}
+	// metaStorageFsyncLatency tracks the primary WAL device latency.
+	// For secondary WAL device latency (when WAL failover is configured),
+	// see metaStorageWALSecondaryFileOpLatency.
 	metaStorageFsyncLatency = metric.Metadata{
 		Name:        "storage.wal.fsync.latency",
 		Help:        "The fsync latency to the Write-Ahead Log device.",
@@ -2854,6 +2857,14 @@ Note that the measurement does not include the duration for replicating the eval
 			"When WAL failover is configured, the more relevant metric is storage.wal.failover_write_and_sync.latency, as " +
 			"this metric reflects the fsync latency of the primary and/or the secondary WAL device.",
 	}
+	metaStorageWALSecondaryFileOpLatency = metric.Metadata{
+		Name:        "storage.wal.secondary.file_op.latency",
+		Help:        "The latency of file operations on the secondary Write-Ahead Log device.",
+		Measurement: "File Op Latency",
+		Unit:        metric.Unit_NANOSECONDS,
+		Category:    metric.Metadata_STORAGE,
+		HowToUse:    "Only populated when WAL failover is configured. This metric tracks file operation latency specifically on the secondary WAL device.",
+	}
 	metaStorageWALFailoverSwitchCount = metric.Metadata{
 		Name: "storage.wal.failover.switch.count",
 		Help: "Count of the number of times WAL writing has switched from primary to secondary " +
@@ -3452,7 +3463,12 @@ type StoreMetrics struct {
 	SubsumeLocksWritten *metric.Counter
 
 	FlushUtilization *metric.GaugeFloat64
-	FsyncLatency     *metric.ManualWindowHistogram
+	// FsyncLatency tracks file operation latency for the primary WAL device.
+	// When WAL failover is configured, see also WALSecondaryFileOpLatency.
+	FsyncLatency *metric.ManualWindowHistogram
+	// WALSecondaryFileOpLatency tracks file operation latency for the secondary
+	// WAL device. Only populated when WAL failover is configured.
+	WALSecondaryFileOpLatency *metric.ManualWindowHistogram
 
 	// Disk metrics
 	DiskReadBytes              *metric.Counter
@@ -4266,6 +4282,11 @@ func newStoreMetrics(histogramWindow time.Duration) *StoreMetrics {
 			pebble.FsyncLatencyBuckets,
 			false, /* withRotate */
 		),
+		WALSecondaryFileOpLatency: metric.NewManualWindowHistogram(
+			metaStorageWALSecondaryFileOpLatency,
+			pebble.FsyncLatencyBuckets,
+			false, /* withRotate */
+		),
 
 		ReplicaReadBatchDroppedLatchesBeforeEval: metric.NewCounter(metaReplicaReadBatchDroppedLatchesBeforeEval),
 		ReplicaReadBatchWithoutInterleavingIter:  metric.NewCounter(metaReplicaReadBatchWithoutInterleavingIter),

pkg/kv/kvserver/metrics_test.go

@@ -125,3 +125,36 @@ func TestPebbleDiskWriteMetrics(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+// TestWALSecondaryFileOpLatencyMetric verifies that the secondary WAL file
+// operation latency metric is properly registered and accessible.
+func TestWALSecondaryFileOpLatencyMetric(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	defer log.Scope(t).Close(t)
+
+	tmpDir, cleanup := testutils.TempDir(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	ts, _, _ := serverutils.StartServer(t, base.TestServerArgs{
+		DefaultTestTenant: base.TestControlsTenantsExplicitly,
+		StoreSpecs: []base.StoreSpec{
+			{Size: storageconfig.BytesSize(storageconfig.MinimumStoreSize), Path: tmpDir},
+		},
+	})
+	defer ts.Stopper().Stop(ctx)
+
+	// Verify the secondary WAL file operation latency metric is registered.
+	if err := ts.GetStores().(*Stores).VisitStores(func(s *Store) error {
+		if ok := s.Registry().Contains("storage.wal.secondary.file_op.latency"); !ok {
+			return fmt.Errorf("missing secondary WAL file operation latency metric")
+		}
+		// Verify the metric is non-nil in the store metrics.
+		if s.metrics.WALSecondaryFileOpLatency == nil {
+			return fmt.Errorf("WALSecondaryFileOpLatency metric is nil")
+		}
+		return nil
+	}); err != nil {
+		t.Fatal(err)
+	}
+}

pkg/kv/kvserver/raftstorebench/stats.go

@@ -90,11 +90,22 @@ func newAggStats() *aggStats {
 func printLogWriterMetrics(t T, prefix string, m storage.Metrics) {
 	var b strings.Builder
 	_, _ = fmt.Fprintf(&b, "%s logWriter: rate(peak): %s(%s) len(pending,sync): (%.2f,%.2f)",
-		prefix, humanize.IBytes(uint64(m.LogWriter.WriteThroughput.Rate())),
-		humanize.IBytes(uint64(m.LogWriter.WriteThroughput.PeakRate())),
-		m.LogWriter.PendingBufferLen.Mean(), m.LogWriter.SyncQueueLen.Mean())
-	qs := calculateQuantiles(m.LogWriter.FsyncLatency, 0.5, 0.9, 0.99)
-	_, _ = fmt.Fprintf(&b, " sync: p50,p90,p99: %.2fms,%.2fms,%.2fms", qs[0]/1e6, qs[1]/1e6, qs[2]/1e6)
+		prefix, humanize.IBytes(uint64(m.Metrics.WALMetrics.WriteThroughput.Rate())),
+		humanize.IBytes(uint64(m.Metrics.WALMetrics.WriteThroughput.PeakRate())),
+		m.Metrics.WALMetrics.PendingBufferLen.Mean(), m.Metrics.WALMetrics.SyncQueueLen.Mean())
+
+	// Log primary file operation latency
+	qsPrimary := calculateQuantiles(m.Metrics.WALMetrics.PrimaryFileOpLatency, 0.5, 0.9, 0.99)
+	_, _ = fmt.Fprintf(&b, " primary: p50,p90,p99: %.2fms,%.2fms,%.2fms",
+		qsPrimary[0]/1e6, qsPrimary[1]/1e6, qsPrimary[2]/1e6)
+
+	// Log secondary file operation latency if available (WAL failover scenarios)
+	if m.Metrics.WALMetrics.SecondaryFileOpLatency != nil {
+		qsSecondary := calculateQuantiles(m.Metrics.WALMetrics.SecondaryFileOpLatency, 0.5, 0.9, 0.99)
+		_, _ = fmt.Fprintf(&b, " secondary: p50,p90,p99: %.2fms,%.2fms,%.2fms",
+			qsSecondary[0]/1e6, qsSecondary[1]/1e6, qsSecondary[2]/1e6)
+	}
+
 	logf(t, "%s", &b)
 }
 

pkg/kv/kvserver/store.go

@@ -3813,9 +3813,15 @@ func (s *Store) ComputeMetricsPeriodically(
 		wt.Subtract(prevMetrics.FlushWriteThroughput)
 
 		if err := updateWindowedHistogram(
-			prevMetrics.WALFsyncLatency, m.LogWriter.FsyncLatency, s.metrics.FsyncLatency); err != nil {
+			prevMetrics.WALFsyncLatency, m.Metrics.WALMetrics.PrimaryFileOpLatency, s.metrics.FsyncLatency); err != nil {
 			return m, err
 		}
+		if m.Metrics.WALMetrics.SecondaryFileOpLatency != nil {
+			if err := updateWindowedHistogram(
+				prevMetrics.WALSecondaryFileOpLatency, m.Metrics.WALMetrics.SecondaryFileOpLatency, s.metrics.WALSecondaryFileOpLatency); err != nil {
+				return m, err
+			}
+		}
 		if m.WAL.Failover.FailoverWriteAndSyncLatency != nil {
 			if err := updateWindowedHistogram(prevMetrics.WALFailoverWriteAndSyncLatency,
 				m.WAL.Failover.FailoverWriteAndSyncLatency, s.metrics.WALFailoverWriteAndSyncLatency); err != nil {

pkg/roachprod/agents/opentelemetry/cockroachdb_metrics.go

@@ -2447,6 +2447,10 @@ var cockroachdbMetrics = map[string]string{
     "storage_wal_fsync_latency_bucket": "storage.wal.fsync.latency.bucket",
     "storage_wal_fsync_latency_count": "storage.wal.fsync.latency.count",
     "storage_wal_fsync_latency_sum": "storage.wal.fsync.latency.sum",
+    "storage_wal_secondary_file_op_latency": "storage.wal.secondary.file_op.latency",
+    "storage_wal_secondary_file_op_latency_bucket": "storage.wal.secondary.file_op.latency.bucket",
+    "storage_wal_secondary_file_op_latency_count": "storage.wal.secondary.file_op.latency.count",
+    "storage_wal_secondary_file_op_latency_sum": "storage.wal.secondary.file_op.latency.sum",
     "storage_write_amplification": "storage.write_amplification",
     "storage_write_stall_nanos": "storage.write_stall_nanos",
     "storage_write_stalls": "storage.write.stalls",

pkg/server/node.go

@@ -1219,7 +1219,7 @@ func (n *Node) computeMetricsPeriodically(
 			} else {
 				storeToMetrics[store].FlushWriteThroughput = newMetrics.Flush.WriteThroughput
 			}
-			if err := newMetrics.LogWriter.FsyncLatency.Write(&storeToMetrics[store].WALFsyncLatency); err != nil {
+			if err := newMetrics.Metrics.WALMetrics.PrimaryFileOpLatency.Write(&storeToMetrics[store].WALFsyncLatency); err != nil {
 				return err
 			}
 			if newMetrics.WAL.Failover.FailoverWriteAndSyncLatency != nil {
@@ -1228,6 +1228,12 @@ func (n *Node) computeMetricsPeriodically(
 					return err
 				}
 			}
+			if newMetrics.Metrics.WALMetrics.SecondaryFileOpLatency != nil {
+				if err := newMetrics.Metrics.WALMetrics.SecondaryFileOpLatency.Write(
+					&storeToMetrics[store].WALSecondaryFileOpLatency); err != nil {
+					return err
+				}
+			}
 		}
 		return nil
 	})

pkg/storage/engine.go

@@ -1337,6 +1337,7 @@ type MetricsForInterval struct {
 	WALFsyncLatency                prometheusgo.Metric
 	FlushWriteThroughput           pebble.ThroughputMetric
 	WALFailoverWriteAndSyncLatency prometheusgo.Metric
+	WALSecondaryFileOpLatency      prometheusgo.Metric
 }
 
 // NumSSTables returns the total number of SSTables in the LSM, aggregated