storage: revert cluster setting to expire sticky bits

Reverts #37728. A cluster setting is coarse to be useful. There could be
instances where multiple people are working in the same cluster and
there would be conflicts on when they want their sticky bits to expire.

Release note(general change): Remove kv.range_merge.manual_split_ttl
                              setting

docs/generated/settings/settings.html

@@ -43,7 +43,6 @@
 <tr><td><code>kv.raft_log.disable_synchronization_unsafe</code></td><td>boolean</td><td><code>false</code></td><td>set to true to disable synchronization on Raft log writes to persistent storage. Setting to true risks data loss or data corruption on server crashes. The setting is meant for internal testing only and SHOULD NOT be used in production.</td></tr>
 <tr><td><code>kv.range.backpressure_range_size_multiplier</code></td><td>float</td><td><code>2</code></td><td>multiple of range_max_bytes that a range is allowed to grow to without splitting before writes to that range are blocked, or 0 to disable</td></tr>
 <tr><td><code>kv.range_descriptor_cache.size</code></td><td>integer</td><td><code>1000000</code></td><td>maximum number of entries in the range descriptor and leaseholder caches</td></tr>
-<tr><td><code>kv.range_merge.manual_split.ttl</code></td><td>duration</td><td><code>0s</code></td><td>if nonzero, manual splits older than this duration will be considered for automatic range merging</td></tr>
 <tr><td><code>kv.range_merge.queue_enabled</code></td><td>boolean</td><td><code>true</code></td><td>whether the automatic merge queue is enabled</td></tr>
 <tr><td><code>kv.range_merge.queue_interval</code></td><td>duration</td><td><code>1s</code></td><td>how long the merge queue waits between processing replicas (WARNING: may compromise cluster stability or correctness; do not edit without supervision)</td></tr>
 <tr><td><code>kv.range_split.by_load_enabled</code></td><td>boolean</td><td><code>true</code></td><td>allow automatic splits of ranges based on where load is concentrated</td></tr>

pkg/storage/client_merge_test.go

@@ -3275,24 +3275,18 @@ func TestMergeQueue(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 
 	ctx := context.Background()
-	manualClock := hlc.NewManualClock(123)
-	clock := hlc.NewClock(manualClock.UnixNano, time.Nanosecond)
 	storeCfg := storage.TestStoreConfig(nil)
 	storeCfg.TestingKnobs.DisableSplitQueue = true
 	storeCfg.TestingKnobs.DisableScanner = true
 	sv := &storeCfg.Settings.SV
 	storagebase.MergeQueueEnabled.Override(sv, true)
 	storage.MergeQueueInterval.Override(sv, 0) // process greedily
-	manualSplitTTL := time.Millisecond * 200
-	storage.ManualSplitTTL.Override(sv, manualSplitTTL)
 	var mtc multiTestContext
 	// This test was written before the multiTestContext started creating many
 	// system ranges at startup, and hasn't been update to take that into account.
 	mtc.startWithSingleRange = true
 
 	mtc.storeConfig = &storeCfg
-	// Inject clock for manipulation in tests
-	mtc.clock = clock
 	mtc.Start(t, 2)
 	defer mtc.Stop()
 	mtc.initGossipNetwork() // needed for the non-collocated case's rebalancing to work
@@ -3447,28 +3441,6 @@ func TestMergeQueue(t *testing.T) {
 		store.MustForceMergeScanAndProcess()
 		verifyMerged(t)
 	})
-
-	t.Run("sticky bit ttl", func(t *testing.T) {
-		reset(t)
-		store.MustForceMergeScanAndProcess()
-		verifyUnmerged(t)
-
-		// Perform manual merge and verify that no merge occurred.
-		split(t, rhsStartKey.AsRawKey(), true /* manual */)
-		clearRange(t, lhsStartKey, rhsEndKey)
-		store.MustForceMergeScanAndProcess()
-		verifyUnmerged(t)
-
-		// Sticky bit is not expired yet.
-		manualClock.Set(manualSplitTTL.Nanoseconds())
-		store.MustForceMergeScanAndProcess()
-		verifyUnmerged(t)
-
-		// Sticky bit is expired.
-		manualClock.Set(manualSplitTTL.Nanoseconds() * 2)
-		store.MustForceMergeScanAndProcess()
-		verifyMerged(t)
-	})
 }
 
 func TestInvalidSubsumeRequest(t *testing.T) {

pkg/storage/merge_queue.go

@@ -56,17 +56,6 @@ var MergeQueueInterval = func() *settings.DurationSetting {
 	return s
 }()
 
-// ManualSplitTTL is the amount of time that the merge queue will not consider
-// a manually split range for merging if it is nonzero. If ManualSplitTTL is
-// zero, then no manual splits are considered for automatic merging. If a range
-// is split in a LHS and a RHS, then the merge queue will not consider to merge
-// the RHS with the range to its left until ManualSplitTTL time has passed.
-var ManualSplitTTL = settings.RegisterNonNegativeDurationSetting(
-	"kv.range_merge.manual_split.ttl",
-	"if nonzero, manual splits older than this duration will be considered for automatic range merging",
-	0,
-)
-
 // mergeQueue manages a queue of ranges slated to be merged with their right-
 // hand neighbor.
 //
@@ -300,17 +289,12 @@ func (mq *mergeQueue) process(
 		}
 	}
 
-	// Range was manually split and not expired, so skip merging.
+	// Range was manually split, so skip merging.
 	if rhsDesc.StickyBit != nil {
-		manualSplitTTL := ManualSplitTTL.Get(&mq.store.ClusterSettings().SV)
-		manualSplitExpired := manualSplitTTL != 0 && rhsDesc.StickyBit.GoTime().Add(manualSplitTTL).Before(mq.store.Clock().PhysicalTime())
-		if !manualSplitExpired {
-			log.VEventf(ctx, 2, "skipping merge: ranges were manually split and sticky bit was not expired")
-			// TODO(jeffreyxiao): Consider returning a purgatory error to avoid
-			// repeatedly processing ranges that cannot be merged.
-			return nil
-		}
-		log.VEventf(ctx, 2, "ranges were manually split, but sticky bit was expired")
+		log.VEventf(ctx, 2, "skipping merge: ranges were manually split")
+		// TODO(jeffreyxiao): Consider returning a purgatory error to avoid
+		// repeatedly processing ranges that cannot be merged.
+		return nil
 	}
 
 	log.VEventf(ctx, 2, "merging to produce range: %s-%s", mergedDesc.StartKey, mergedDesc.EndKey)