Added index for member_approval on member_namespace_id and status

Changelog: performance

db/migrate/20240410061546_add_index_for_member_approvals_member_namespace_id_status.rb

+# frozen_string_literal: true
+
+class AddIndexForMemberApprovalsMemberNamespaceIdStatus < Gitlab::Database::Migration[2.2]
+  disable_ddl_transaction!
+  milestone '16.11'
+
+  INDEX_NAME = 'index_member_approvals_on_member_namespace_id_status'
+
+  def up
+    add_concurrent_index :member_approvals, [:member_namespace_id, :status], where: 'status = 0', name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :member_approvals, INDEX_NAME
+  end
+end

db/schema_migrations/20240410061546

+90dda8138e958b31a29a180fe5023417418da6862d8621e7b89d80e5d8abd3da
\ No newline at end of file

db/structure.sql

@@ -25907,6 +25907,8 @@ CREATE INDEX index_member_approval_on_requested_by_id ON member_approvals USING
 CREATE INDEX index_member_approval_on_reviewed_by_id ON member_approvals USING btree (reviewed_by_id);
+CREATE INDEX index_member_approvals_on_member_namespace_id_status ON member_approvals USING btree (member_namespace_id, status) WHERE (status = 0);
+
 CREATE INDEX index_member_approvals_on_member_role_id ON member_approvals USING btree (member_role_id);
 CREATE INDEX index_member_approvals_on_user_id ON member_approvals USING btree (user_id);