Use a single query to compute excess storage

Currently, we do 2 separate queries to compute excess storage for
projects with project-level limits and those that inherit the global
limit.

This improves the calculation so that it does both in one query.

ee/app/models/ee/namespace.rb

@@ -202,22 +202,15 @@ module EE
 
     def total_repository_size_excess
       strong_memoize(:total_repository_size_excess) do
-        namespace_size_limit = actual_size_limit
-        namespace_limit_arel = Arel::Nodes::SqlLiteral.new(namespace_size_limit.to_s.presence || 'NULL')
+        total_excess = (total_repository_size_arel - repository_size_limit_arel).sum
 
-        total_excess = total_repository_size_excess_calculation(::Project.arel_table[:repository_size_limit])
-        total_excess += total_repository_size_excess_calculation(namespace_limit_arel, project_level: false) if namespace_size_limit.to_i > 0
-        total_excess
+        projects_for_repository_size_excess.pluck(total_excess).first || 0
       end
     end
 
     def repository_size_excess_project_count
       strong_memoize(:repository_size_excess_project_count) do
-        namespace_size_limit = actual_size_limit
-
-        count = projects_for_repository_size_excess.count
-        count += projects_for_repository_size_excess(namespace_size_limit).count if namespace_size_limit.to_i > 0
-        count
+        projects_for_repository_size_excess.count
       end
     end
 
@@ -428,26 +421,34 @@ module EE
       )
     end
 
-    def total_repository_size_excess_calculation(repository_size_limit, project_level: true)
-      total_excess = (total_repository_size_arel - repository_size_limit).sum
-      relation = projects_for_repository_size_excess((repository_size_limit unless project_level))
-      relation.pluck(total_excess).first || 0 # rubocop:disable Rails/Pick
-    end
-
     def total_repository_size_arel
       arel_table = ::ProjectStatistics.arel_table
       arel_table[:repository_size] + arel_table[:lfs_objects_size]
     end
 
-    def projects_for_repository_size_excess(limit = nil)
-      if limit
-        all_projects
-          .with_total_repository_size_greater_than(limit)
-          .without_repository_size_limit
+    def projects_for_repository_size_excess
+      projects_with_limits = ::Project.without_unlimited_repository_size_limit
+
+      if actual_size_limit.to_i > 0
+        # When the instance or namespace level limit is set, we need to include those without project level limits
+        projects_with_limits = projects_with_limits.or(::Project.without_repository_size_limit)
+      end
+
+      all_projects
+        .merge(projects_with_limits)
+        .with_total_repository_size_greater_than(repository_size_limit_arel)
+    end
+
+    def repository_size_limit_arel
+      instance_size_limit = actual_size_limit.to_i
+
+      if instance_size_limit > 0
+        self.class.arel_table.coalesce(
+          ::Project.arel_table[:repository_size_limit],
+          instance_size_limit
+        )
       else
-        all_projects
-          .with_total_repository_size_greater_than(::Project.arel_table[:repository_size_limit])
-          .without_unlimited_repository_size_limit
+        ::Project.arel_table[:repository_size_limit]
       end
     end
 

ee/changelogs/unreleased/325344-improve-computation-of-namespace-excess-storage.yml

+---
+title: Improve computation of excess repository storage size
+merge_request: 57088
+author:
+type: performance