spanconfig: rename setting to `spanconfig.storage_coalesce_adjacent.e…

…nabled`

Our terminology is "tenant" vs "storage cluster". The word "host" is
not used anywhere in CockroachDB (it is a term specific to CC
Serverless) and so should not be included in setting names.

There is no release note because the functionality is not yet visible
to end-users.

Release note: None

pkg/settings/registry.go

@@ -159,6 +159,8 @@ var retiredSettings = map[string]struct{}{
 	"sql.distsql.drain.cancel_after_wait.enabled":    {},
 	"changefeed.active_protected_timestamps.enabled": {},
 	"jobs.scheduler.single_node_scheduler.enabled":   {},
+	// renamed.
+	"spanconfig.host_coalesce_adjacent.enabled": {},
 }
 
 // sqlDefaultSettings is the list of "grandfathered" existing sql.defaults

pkg/spanconfig/spanconfigstore/span_store.go

@@ -24,23 +24,23 @@ import (
 	"github.com/cockroachdb/errors"
 )
 
-// tenantCoalesceAdjacentSetting is a hidden cluster setting that controls
-// whether we coalesce adjacent ranges in the tenant keyspace if they have the
-// same span config.
+// tenantCoalesceAdjacentSetting is a hidden cluster setting that
+// controls whether we coalesce adjacent ranges across all secondary
+// tenant keyspaces if they have the same span config.
 var tenantCoalesceAdjacentSetting = settings.RegisterBoolSetting(
 	settings.SystemOnly,
 	"spanconfig.tenant_coalesce_adjacent.enabled",
-	`collapse adjacent ranges with the same span configs`,
+	`collapse adjacent ranges with the same span configs across all secondary tenant keyspaces`,
 	true,
 )
 
-// hostCoalesceAdjacentSetting is a hidden cluster setting that controls
-// whether we coalesce adjacent ranges in the host tenant keyspace if they have
-// the same span config.
-var hostCoalesceAdjacentSetting = settings.RegisterBoolSetting(
+// storageCoalesceAdjacentSetting is a hidden cluster setting that
+// controls whether we coalesce adjacent ranges outside of the
+// secondary tenant keyspaces if they have the same span config.
+var storageCoalesceAdjacentSetting = settings.RegisterBoolSetting(
 	settings.SystemOnly,
-	"spanconfig.host_coalesce_adjacent.enabled",
-	`collapse adjacent ranges with the same span configs`,
+	"spanconfig.storage_coalesce_adjacent.enabled",
+	`collapse adjacent ranges with the same span configs for the ranges specific to the system tenant`,
 	false,
 )
 
@@ -152,7 +152,7 @@ func (s *spanConfigStore) computeSplitKey(start, end roachpb.RKey) (roachpb.RKey
 			// ranges.
 			systemTableUpperBound := keys.SystemSQLCodec.TablePrefix(keys.MaxReservedDescID + 1)
 			if roachpb.Key(rem).Compare(systemTableUpperBound) < 0 ||
-				!hostCoalesceAdjacentSetting.Get(&s.settings.SV) {
+				!storageCoalesceAdjacentSetting.Get(&s.settings.SV) {
 				return roachpb.RKey(match.span.Key), nil
 			}
 		} else {

pkg/sql/generate_objects_test.go

@@ -46,7 +46,7 @@ func BenchmarkGenerateObjects(b *testing.B) {
 
 	// Disable auto stats and range splits, which introduce noise.
 	db.Exec(b, `SET CLUSTER SETTING sql.stats.automatic_collection.enabled = false`)
-	db.Exec(b, `SET CLUSTER SETTING spanconfig.host_coalesce_adjacent.enabled = true`)
+	db.Exec(b, `SET CLUSTER SETTING spanconfig.storage_coalesce_adjacent.enabled = true`)
 
 	for _, bench := range benches {
 		b.Run(bench.name, func(b *testing.B) {