Add rate limiting to user friendships

db/migrate/20210511104518_add_time_to_friendships.rb

@@ -0,0 +1,9 @@
+class AddTimeToFriendships < ActiveRecord::Migration[6.0]
+  disable_ddl_transaction!
+
+  def change
+    add_column :friends, :created_at, :datetime
+    add_index :friends, [:user_id, :created_at], :algorithm => :concurrently
+    remove_index :friends, :column => :user_id, :name => "friends_user_id_idx"
+  end
+end

db/structure.sql

@@ -720,7 +720,8 @@ CREATE TABLE public.diary_entry_subscriptions (
 CREATE TABLE public.friends (
     id bigint NOT NULL,
     user_id bigint NOT NULL,
-    friend_user_id bigint NOT NULL
+    friend_user_id bigint NOT NULL,
+    created_at timestamp without time zone
 );
 
 
@@ -2146,13 +2147,6 @@ CREATE INDEX diary_entry_language_code_created_at_index ON public.diary_entries
 CREATE INDEX diary_entry_user_id_created_at_index ON public.diary_entries USING btree (user_id, created_at);
 
 
---
--- Name: friends_user_id_idx; Type: INDEX; Schema: public; Owner: -
---
-
-CREATE INDEX friends_user_id_idx ON public.friends USING btree (user_id);
-
-
 --
 -- Name: gpx_file_tags_gpxid_idx; Type: INDEX; Schema: public; Owner: -
 --
@@ -2279,6 +2273,13 @@ CREATE INDEX index_client_applications_on_user_id ON public.client_applications
 CREATE INDEX index_diary_entry_subscriptions_on_diary_entry_id ON public.diary_entry_subscriptions USING btree (diary_entry_id);
 
 
+--
+-- Name: index_friends_on_user_id_and_created_at; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE INDEX index_friends_on_user_id_and_created_at ON public.friends USING btree (user_id, created_at);
+
+
 --
 -- Name: index_issue_comments_on_issue_id; Type: INDEX; Schema: public; Owner: -
 --
@@ -3123,6 +3124,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20201006213836'),
 ('20201006220807'),
 ('20201214144017'),
+('20210511104518'),
 ('21'),
 ('22'),
 ('23'),