changefeedccl: rename changefeed.frontier_highwater_lag_checkpoint_th…

…reshold setting

This patch renames
`changefeed.frontier_highwater_lag_checkpoint_threshold`
to `changefeed.span_checkpoint.lag_threshold` for consistency.

Release note (ops change): The cluster setting
`changefeed.frontier_highwater_lag_checkpoint_threshold` has been
renamed to `changefeed.span_checkpoint.lag_threshold`. The old name
remains available for backwards-compatibility.

docs/generated/settings/settings-for-tenants.txt

@@ -17,7 +17,7 @@ changefeed.default_range_distribution_strategy	enumeration	default	configures ho
 changefeed.event_consumer_worker_queue_size	integer	16	if changefeed.event_consumer_workers is enabled, this setting sets the maxmimum number of events which a worker can buffer	application
 changefeed.event_consumer_workers	integer	0	the number of workers to use when processing events: <0 disables, 0 assigns a reasonable default, >0 assigns the setting value. for experimental/core changefeeds and changefeeds using parquet format, this is disabled	application
 changefeed.fast_gzip.enabled	boolean	true	use fast gzip implementation	application
-changefeed.frontier_highwater_lag_checkpoint_threshold	duration	10m0s	controls the maximum the high-water mark is allowed to lag behind the leading spans of the frontier before per-span checkpointing is enabled; if 0, checkpointing due to high-water lag is disabled	application
+changefeed.span_checkpoint.lag_threshold (alias: changefeed.frontier_highwater_lag_checkpoint_threshold)	duration	10m0s	the amount of time a changefeed's lagging (slowest) spans must lag behind its leading (fastest) spans before a span-level checkpoint to save leading span progress is written; if 0, span-level checkpoints due to lagging spans is disabled	application
 changefeed.memory.per_changefeed_limit	byte size	512 MiB	controls amount of data that can be buffered per changefeed	application
 changefeed.resolved_timestamp.min_update_interval (alias: changefeed.min_highwater_advance)	duration	0s	minimum amount of time that must have elapsed since the last time a changefeed's resolved timestamp was updated before it is eligible to be updated again; default of 0 means no minimum interval is enforced but updating will still be limited by the average time it takes to checkpoint progress	application
 changefeed.node_throttle_config	string		specifies node level throttling configuration for all changefeeeds	application

docs/generated/settings/settings.html

@@ -22,7 +22,7 @@
 <tr><td><div id="setting-changefeed-event-consumer-worker-queue-size" class="anchored"><code>changefeed.event_consumer_worker_queue_size</code></div></td><td>integer</td><td><code>16</code></td><td>if changefeed.event_consumer_workers is enabled, this setting sets the maxmimum number of events which a worker can buffer</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-changefeed-event-consumer-workers" class="anchored"><code>changefeed.event_consumer_workers</code></div></td><td>integer</td><td><code>0</code></td><td>the number of workers to use when processing events: &lt;0 disables, 0 assigns a reasonable default, &gt;0 assigns the setting value. for experimental/core changefeeds and changefeeds using parquet format, this is disabled</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-changefeed-fast-gzip-enabled" class="anchored"><code>changefeed.fast_gzip.enabled</code></div></td><td>boolean</td><td><code>true</code></td><td>use fast gzip implementation</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
-<tr><td><div id="setting-changefeed-frontier-highwater-lag-checkpoint-threshold" class="anchored"><code>changefeed.frontier_highwater_lag_checkpoint_threshold</code></div></td><td>duration</td><td><code>10m0s</code></td><td>controls the maximum the high-water mark is allowed to lag behind the leading spans of the frontier before per-span checkpointing is enabled; if 0, checkpointing due to high-water lag is disabled</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
+<tr><td><div id="setting-changefeed-frontier-highwater-lag-checkpoint-threshold" class="anchored"><code>changefeed.span_checkpoint.lag_threshold<br />(alias: changefeed.frontier_highwater_lag_checkpoint_threshold)</code></div></td><td>duration</td><td><code>10m0s</code></td><td>the amount of time a changefeed&#39;s lagging (slowest) spans must lag behind its leading (fastest) spans before a span-level checkpoint to save leading span progress is written; if 0, span-level checkpoints due to lagging spans is disabled</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-changefeed-memory-per-changefeed-limit" class="anchored"><code>changefeed.memory.per_changefeed_limit</code></div></td><td>byte size</td><td><code>512 MiB</code></td><td>controls amount of data that can be buffered per changefeed</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-changefeed-min-highwater-advance" class="anchored"><code>changefeed.resolved_timestamp.min_update_interval<br />(alias: changefeed.min_highwater_advance)</code></div></td><td>duration</td><td><code>0s</code></td><td>minimum amount of time that must have elapsed since the last time a changefeed&#39;s resolved timestamp was updated before it is eligible to be updated again; default of 0 means no minimum interval is enforced but updating will still be limited by the average time it takes to checkpoint progress</td><td>Serverless/Dedicated/Self-Hosted</td></tr>
 <tr><td><div id="setting-changefeed-node-throttle-config" class="anchored"><code>changefeed.node_throttle_config</code></div></td><td>string</td><td><code></code></td><td>specifies node level throttling configuration for all changefeeeds</td><td>Serverless/Dedicated/Self-Hosted</td></tr>

pkg/ccl/changefeedccl/changefeed_test.go

@@ -2340,7 +2340,7 @@ func TestChangefeedLaggingSpanCheckpointing(t *testing.T) {
 		context.Background(), &s.ClusterSettings().SV, 10*time.Millisecond)
 	changefeedbase.SpanCheckpointMaxBytes.Override(
 		context.Background(), &s.ClusterSettings().SV, 100<<20)
-	changefeedbase.FrontierHighwaterLagCheckpointThreshold.Override(
+	changefeedbase.SpanCheckpointLagThreshold.Override(
 		context.Background(), &s.ClusterSettings().SV, 10*time.Millisecond)
 
 	// We'll start changefeed with the cursor.

pkg/ccl/changefeedccl/changefeedbase/settings.go

@@ -79,16 +79,21 @@ var SpanCheckpointInterval = settings.RegisterDurationSetting(
 	settings.WithName("changefeed.span_checkpoint.interval"),
 )
 
-// FrontierHighwaterLagCheckpointThreshold controls the amount the high-water
-// mark is allowed to lag behind the leading edge of the frontier before we
-// begin to attempt checkpointing spans above the high-water mark
-var FrontierHighwaterLagCheckpointThreshold = settings.RegisterDurationSetting(
+// SpanCheckpointLagThreshold controls the amount of time a changefeed's
+// lagging spans must lag behind its leading spans before a span-level
+// checkpoint is written.
+var SpanCheckpointLagThreshold = settings.RegisterDurationSetting(
 	settings.ApplicationLevel,
 	"changefeed.frontier_highwater_lag_checkpoint_threshold",
-	"controls the maximum the high-water mark is allowed to lag behind the leading spans of the frontier before per-span checkpointing is enabled; if 0, checkpointing due to high-water lag is disabled",
+	"the amount of time a changefeed's lagging (slowest) spans must lag "+
+		"behind its leading (fastest) spans before a span-level checkpoint "+
+		"to save leading span progress is written; if 0, span-level checkpoints "+
+		"due to lagging spans is disabled",
 	10*time.Minute,
 	settings.NonNegativeDuration,
-	settings.WithPublic)
+	settings.WithPublic,
+	settings.WithName("changefeed.span_checkpoint.lag_threshold"),
+)
 
 // SpanCheckpointMaxBytes controls the maximum number of key bytes that will be added
 // to a span-level checkpoint record.

pkg/ccl/changefeedccl/resolvedspan/frontier.go

@@ -295,9 +295,9 @@ func (f *resolvedSpanFrontier) assertBoundaryNotEarlier(
 
 // HasLaggingSpans returns whether the frontier has lagging spans as defined
 // by whether the frontier trails the latest timestamp by at least
-// changefeedbase.FrontierHighwaterLagCheckpointThreshold.
+// changefeedbase.SpanCheckpointLagThreshold.
 func (f *resolvedSpanFrontier) HasLaggingSpans(sv *settings.Values) bool {
-	lagThresholdNanos := int64(changefeedbase.FrontierHighwaterLagCheckpointThreshold.Get(sv))
+	lagThresholdNanos := int64(changefeedbase.SpanCheckpointLagThreshold.Get(sv))
 	if lagThresholdNanos == 0 {
 		return false
 	}