sql/schema: re-organize the UnleasableSystemDescriptors set

pkg/sql/catalog/descs/leased_descriptors.go

@@ -98,12 +98,8 @@ func (ld *leasedDescriptors) getByName(
 		return cached.(lease.LeasedDescriptor).Underlying(), false, nil
 	}
 
-	for _, d := range systemschema.UnleasableSystemDescriptors {
-		if parentID == d.GetParentID() &&
-			parentSchemaID == d.GetParentSchemaID() &&
-			name == d.GetName() {
-			return nil, true, nil
-		}
+	if systemschema.IsUnleasableSystemDescriptorByName(parentID, parentSchemaID, name) {
+		return nil, true, nil
 	}
 
 	readTimestamp := txn.ReadTimestamp()
@@ -128,7 +124,7 @@ func (ld *leasedDescriptors) getByID(
 		return cached.(lease.LeasedDescriptor).Underlying(), false, nil
 	}
 
-	if _, isUnleasable := systemschema.UnleasableSystemDescriptors[id]; isUnleasable {
+	if systemschema.IsUnleasableSystemDescriptorByID(id) {
 		return nil, true, nil
 	}
 

pkg/sql/catalog/systemschema/system.go

@@ -2291,23 +2291,66 @@ var (
 			}}
 		},
 	)
+)
 
-	// UnleasableSystemDescriptors contains the system descriptors which cannot
-	// be leased. This includes the lease table itself, among others.
-	UnleasableSystemDescriptors = func(s []catalog.Descriptor) map[descpb.ID]catalog.Descriptor {
-		m := make(map[descpb.ID]catalog.Descriptor, len(s))
-		for _, d := range s {
-			m[d.GetID()] = d
-		}
-		return m
-	}([]catalog.Descriptor{
+type descRefByName struct {
+	parentID       descpb.ID
+	parentSchemaID descpb.ID
+	name           string
+}
+
+var (
+	// UnleasableSystemDescriptors contains the system descriptors which
+	// cannot be leased. This includes the lease table itself, among others.
+	UnleasableSystemDescriptors = []catalog.Descriptor{
 		SystemDB,
 		LeaseTable,
 		DescriptorTable,
 		NamespaceTable,
 		RangeEventTable,
-	})
+	}
+
+	unleasableSystemDescriptorsByID = func(s []catalog.Descriptor) map[descpb.ID]struct{} {
+		m := make(map[descpb.ID]struct{}, len(s))
+		for _, d := range s {
+			m[d.GetID()] = struct{}{}
+		}
+		return m
+	}(UnleasableSystemDescriptors)
+
+	unleasableSystemDescriptorsByName = func(s []catalog.Descriptor) map[descRefByName]struct{} {
+		m := make(map[descRefByName]struct{}, len(s))
+		for _, d := range s {
+			m[descRefByName{
+				parentID:       d.GetParentID(),
+				parentSchemaID: d.GetParentSchemaID(),
+				name:           d.GetName(),
+			}] = struct{}{}
+		}
+		return m
+	}(UnleasableSystemDescriptors)
 )
 
+// IsUnleasableSystemDescriptorByID returns whether the specified descriptor is
+// a member of the UnleasableSystemDescriptors set, given an ID.
+func IsUnleasableSystemDescriptorByID(id descpb.ID) bool {
+	_, ok := unleasableSystemDescriptorsByID[id]
+	return ok
+}
+
+// IsUnleasableSystemDescriptorByName returns whether the specified descriptor
+// is a member of the UnleasableSystemDescriptors set, given a database, schema,
+// and name.
+func IsUnleasableSystemDescriptorByName(
+	parentID descpb.ID, parentSchemaID descpb.ID, name string,
+) bool {
+	_, ok := unleasableSystemDescriptorsByName[descRefByName{
+		parentID:       parentID,
+		parentSchemaID: parentSchemaID,
+		name:           name,
+	}]
+	return ok
+}
+
 // SpanConfigurationsTableName represents system.span_configurations.
 var SpanConfigurationsTableName = tree.NewTableNameWithSchema("system", tree.PublicSchemaName, tree.Name(catconstants.SpanConfigurationsTableName))