Exclude lingering indexes from reindexing

lib/gitlab/database/reindexing.rb

@@ -10,6 +10,13 @@ module Gitlab
           end
         end
       end
+
+      def self.candidate_indexes
+        Gitlab::Database::PostgresIndex
+          .regular
+          .not_match("^#{ConcurrentReindex::TEMPORARY_INDEX_PREFIX}")
+          .not_match("^#{ConcurrentReindex::REPLACED_INDEX_PREFIX}")
+      end
     end
   end
 end

lib/tasks/gitlab/db.rake

@@ -177,7 +177,7 @@ namespace :gitlab do
       indexes = if args[:index_name]
                   Gitlab::Database::PostgresIndex.by_identifier(args[:index_name])
                 else
-                  Gitlab::Database::PostgresIndex.regular.random_few(2)
+                  Gitlab::Database::Reindexing.candidate_indexes.random_few(2)
                 end
 
       Gitlab::Database::Reindexing.perform(indexes)

spec/lib/gitlab/database/reindexing_spec.rb

@@ -52,4 +52,15 @@ RSpec.describe Gitlab::Database::Reindexing do
       it_behaves_like 'reindexing'
     end
   end
+
+  describe '.candidate_indexes' do
+    subject { described_class.candidate_indexes }
+
+    it 'retrieves regular indexes that are no left-overs from previous runs' do
+      result = double
+      expect(Gitlab::Database::PostgresIndex).to receive_message_chain('regular.not_match.not_match').with(no_args).with('^tmp_reindex_').with('^old_reindex_').and_return(result)
+
+      expect(subject).to eq(result)
+    end
+  end
 end

spec/tasks/gitlab/db_rake_spec.rb

@@ -170,7 +170,7 @@ RSpec.describe 'gitlab:db namespace rake task' do
 
     context 'when no index_name is given' do
       it 'rebuilds a random number of large indexes' do
-        expect(Gitlab::Database::PostgresIndex).to receive_message_chain('regular.random_few').and_return(indexes)
+        expect(Gitlab::Database::Reindexing).to receive_message_chain('candidate_indexes.random_few').and_return(indexes)
         expect(Gitlab::Database::Reindexing).to receive(:perform).with(indexes)
 
         run_rake_task('gitlab:db:reindex')