Add unique index for Helm packages

Changelog: added

db/migrate/20210614143954_add_unique_index_for_helm_packages.rb

+# frozen_string_literal: true
+
+class AddUniqueIndexForHelmPackages < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  INDEX_NAME = 'index_packages_on_project_id_name_version_unique_when_helm'
+  PACKAGE_TYPE_HELM = 11
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :packages_packages, [:project_id, :name, :version], unique: true, where: "package_type = #{PACKAGE_TYPE_HELM}", name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :packages_packages, INDEX_NAME
+  end
+end

db/schema_migrations/20210614143954

+b958d65f1b3b43d7bcd2a703489132ba9a2ba1e0374d45533399355ce6be9365
\ No newline at end of file

db/structure.sql

@@ -24117,6 +24117,8 @@ CREATE UNIQUE INDEX index_packages_on_project_id_name_version_unique_when_generi
 
 CREATE UNIQUE INDEX index_packages_on_project_id_name_version_unique_when_golang ON packages_packages USING btree (project_id, name, version) WHERE (package_type = 8);
 
+CREATE UNIQUE INDEX index_packages_on_project_id_name_version_unique_when_helm ON packages_packages USING btree (project_id, name, version) WHERE (package_type = 11);
+
 CREATE INDEX index_packages_package_file_build_infos_on_package_file_id ON packages_package_file_build_infos USING btree (package_file_id);
 
 CREATE INDEX index_packages_package_file_build_infos_on_pipeline_id ON packages_package_file_build_infos USING btree (pipeline_id);