changefeedccl: enable frontier quantization

Previously, all checkpoint timestamps were forwarded precisely to the resolved
timestamp. To improve merging of adjacent frontier spans, this patch introduces
a frontier quantization mode. In this mode, resolved timestamps from rangefeeds
are rounded down to the nearest multiple of the quantization granularity.
Rounding down ensures no progress is missed and that we consistently track the
lowest possible resolved timestamp.

Resolves: #125723
Release note: changefeed.frontier.timestamp_granularity (default off)
has been introduced to enable more efficient tracking of resolved timestamps.

pkg/ccl/changefeedccl/changefeedbase/settings.go

@@ -335,3 +335,10 @@ var DefaultLaggingRangesThreshold = 3 * time.Minute
 // DefaultLaggingRangesPollingInterval is the default polling rate at which
 // lagging ranges are checked and metrics are updated.
 var DefaultLaggingRangesPollingInterval = 1 * time.Minute
+
+var Quantize = settings.RegisterDurationSettingWithExplicitUnit(
+	settings.ApplicationLevel,
+	"changefeed.frontier.timestamp_granularity",
+	"the granularity at which changefeed progress are quantized to make tracking more efficient",
+	0,
+)

pkg/ccl/changefeedccl/kvfeed/BUILD.bazel

@@ -63,6 +63,7 @@ go_test(
         "//pkg/kv",
         "//pkg/kv/kvclient/kvcoord",
         "//pkg/kv/kvpb",
+        "//pkg/kv/kvserver/rangefeed",
         "//pkg/roachpb",
         "//pkg/security/securityassets",
         "//pkg/security/securitytest",

pkg/ccl/changefeedccl/kvfeed/kv_feed.go

@@ -126,6 +126,7 @@ func Run(ctx context.Context, cfg Config) error {
 		cfg.Writer, cfg.Spans, cfg.CheckpointSpans, cfg.CheckpointTimestamp,
 		cfg.SchemaChangeEvents, cfg.SchemaChangePolicy,
 		cfg.NeedsInitialScan, cfg.WithDiff, cfg.WithFiltering,
+		changefeedbase.Quantize.Get(&cfg.Settings.SV),
 		cfg.ConsumerID,
 		cfg.InitialHighWater, cfg.EndTime,
 		cfg.Codec,
@@ -246,17 +247,18 @@ func (e schemaChangeDetectedError) Error() string {
 }
 
 type kvFeed struct {
-	spans               []roachpb.Span
-	checkpoint          []roachpb.Span
-	checkpointTimestamp hlc.Timestamp
-	withDiff            bool
-	withFiltering       bool
-	withInitialBackfill bool
-	consumerID          int64
-	initialHighWater    hlc.Timestamp
-	endTime             hlc.Timestamp
-	writer              kvevent.Writer
-	codec               keys.SQLCodec
+	spans                []roachpb.Span
+	checkpoint           []roachpb.Span
+	checkpointTimestamp  hlc.Timestamp
+	withFrontierQuantize time.Duration
+	withDiff             bool
+	withFiltering        bool
+	withInitialBackfill  bool
+	consumerID           int64
+	initialHighWater     hlc.Timestamp
+	endTime              hlc.Timestamp
+	writer               kvevent.Writer
+	codec                keys.SQLCodec
 
 	onBackfillCallback func() func()
 	rangeObserver      kvcoord.RangeObserver
@@ -283,6 +285,7 @@ func newKVFeed(
 	schemaChangeEvents changefeedbase.SchemaChangeEventClass,
 	schemaChangePolicy changefeedbase.SchemaChangePolicy,
 	withInitialBackfill, withDiff, withFiltering bool,
+	withFrontierQuantize time.Duration,
 	consumerID int64,
 	initialHighWater hlc.Timestamp,
 	endTime hlc.Timestamp,
@@ -296,26 +299,27 @@ func newKVFeed(
 	knobs TestingKnobs,
 ) *kvFeed {
 	return &kvFeed{
-		writer:              writer,
-		spans:               spans,
-		checkpoint:          checkpoint,
-		checkpointTimestamp: checkpointTimestamp,
-		withInitialBackfill: withInitialBackfill,
-		withDiff:            withDiff,
-		withFiltering:       withFiltering,
-		consumerID:          consumerID,
-		initialHighWater:    initialHighWater,
-		endTime:             endTime,
-		schemaChangeEvents:  schemaChangeEvents,
-		schemaChangePolicy:  schemaChangePolicy,
-		codec:               codec,
-		tableFeed:           tf,
-		scanner:             sc,
-		physicalFeed:        pff,
-		bufferFactory:       bf,
-		targets:             targets,
-		timers:              ts,
-		knobs:               knobs,
+		writer:               writer,
+		spans:                spans,
+		checkpoint:           checkpoint,
+		checkpointTimestamp:  checkpointTimestamp,
+		withInitialBackfill:  withInitialBackfill,
+		withDiff:             withDiff,
+		withFiltering:        withFiltering,
+		withFrontierQuantize: withFrontierQuantize,
+		consumerID:           consumerID,
+		initialHighWater:     initialHighWater,
+		endTime:              endTime,
+		schemaChangeEvents:   schemaChangeEvents,
+		schemaChangePolicy:   schemaChangePolicy,
+		codec:                codec,
+		tableFeed:            tf,
+		scanner:              sc,
+		physicalFeed:         pff,
+		bufferFactory:        bf,
+		targets:              targets,
+		timers:               ts,
+		knobs:                knobs,
 	}
 }
 
@@ -598,14 +602,15 @@ func (f *kvFeed) runUntilTableEvent(ctx context.Context, resumeFrontier span.Fro
 
 	g := ctxgroup.WithContext(ctx)
 	physicalCfg := rangeFeedConfig{
-		Spans:         stps,
-		Frontier:      resumeFrontier.Frontier(),
-		WithDiff:      f.withDiff,
-		WithFiltering: f.withFiltering,
-		ConsumerID:    f.consumerID,
-		Knobs:         f.knobs,
-		Timers:        f.timers,
-		RangeObserver: f.rangeObserver,
+		Spans:                stps,
+		Frontier:             resumeFrontier.Frontier(),
+		WithDiff:             f.withDiff,
+		WithFiltering:        f.withFiltering,
+		WithFrontierQuantize: f.withFrontierQuantize,
+		ConsumerID:           f.consumerID,
+		Knobs:                f.knobs,
+		Timers:               f.timers,
+		RangeObserver:        f.rangeObserver,
 	}
 
 	// The following two synchronous calls works as follows: