1 files changed, 36 insertions, 0 deletions
diff --git a/lib/gitlab/database/reindexing/index_selection.rb b/lib/gitlab/database/reindexing/index_selection.rb
new file mode 100644
index 00000000000..406e70791df
--- /dev/null
+++ b/lib/gitlab/database/reindexing/index_selection.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    module Reindexing
+      class IndexSelection
+        include Enumerable
+
+        delegate :each, to: :indexes
+
+        def initialize(candidates)
+          @candidates = candidates
+        end
+
+        private
+
+        attr_reader :candidates
+
+        def indexes
+          # This is an explicit N+1 query:
+          # Bloat estimates are generally available through a view
+          # for all indexes. However, estimating bloat for all
+          # indexes at once is an expensive operation. Therefore,
+          # we force a N+1 pattern here and estimate bloat on a per-index
+          # basis.
+
+          @indexes ||= filter_candidates.sort_by(&:bloat_size).reverse
+        end
+
+        def filter_candidates
+          candidates.not_recently_reindexed
+        end
+      end
+    end
+  end
+end