Add index to project repositories

db/migrate/20201117184334_add_index_to_project_repositories_shard_id_project_id.rb

+# frozen_string_literal: true
+
+class AddIndexToProjectRepositoriesShardIdProjectId < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :project_repositories, [:shard_id, :project_id]
+  end
+
+  def down
+    remove_concurrent_index :project_repositories, [:shard_id, :project_id], name: 'index_project_repositories_on_shard_id_and_project_id'
+  end
+end

db/schema_migrations/20201117184334

+7988d01be5fac0f2a28cc97e309bfa16450d2e376888401fc2ad521aa0082020
\ No newline at end of file

db/structure.sql

@@ -21769,6 +21769,8 @@ CREATE UNIQUE INDEX index_project_repositories_on_project_id ON project_reposito
 
 CREATE INDEX index_project_repositories_on_shard_id ON project_repositories USING btree (shard_id);
 
+CREATE INDEX index_project_repositories_on_shard_id_and_project_id ON project_repositories USING btree (shard_id, project_id);
+
 CREATE UNIQUE INDEX index_project_repository_states_on_project_id ON project_repository_states USING btree (project_id);
 
 CREATE INDEX index_project_repository_storage_moves_on_project_id ON project_repository_storage_moves USING btree (project_id);