Change hashtag trends to be stored in the database instead of redis (#32837)

Co-authored-by: David Roetzel <david@roetzel.de>

db/migrate/20241111141355_create_tag_trends.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class CreateTagTrends < ActiveRecord::Migration[7.2]
+  def change
+    create_table :tag_trends do |t| # rubocop:disable Rails/CreateTableWithTimestamps
+      t.references :tag, null: false, foreign_key: { on_delete: :cascade }, index: false
+      t.float :score, null: false, default: 0
+      t.integer :rank, null: false, default: 0
+      t.boolean :allowed, null: false, default: false
+      t.string :language, null: false, default: ''
+    end
+
+    add_index :tag_trends, [:tag_id, :language], unique: true
+  end
+end

db/post_migrate/20241123160722_move_tag_trends_to_table.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+class MoveTagTrendsToTable < ActiveRecord::Migration[7.2]
+  include Redisable
+
+  disable_ddl_transaction!
+
+  def up
+    redis.zrange('trending_tags:all', 0, -1, with_scores: true).each do |(tag_id, score)|
+      TagTrend.create(
+        tag_id: tag_id,
+        score: score,
+        allowed: redis.zscore('trending_tags:allowed', tag_id).present?
+      )
+    end
+
+    TagTrend.recalculate_ordered_rank
+
+    redis.del('trending_tags:allowed', 'trending_tags:all')
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[7.2].define(version: 2024_11_04_082851) do
+ActiveRecord::Schema[7.2].define(version: 2024_11_23_160722) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
@@ -1080,6 +1080,15 @@ ActiveRecord::Schema[7.2].define(version: 2024_11_04_082851) do
     t.index ["tag_id"], name: "index_tag_follows_on_tag_id"
   end
 
+  create_table "tag_trends", force: :cascade do |t|
+    t.bigint "tag_id", null: false
+    t.float "score", default: 0.0, null: false
+    t.integer "rank", default: 0, null: false
+    t.boolean "allowed", default: false, null: false
+    t.string "language"
+    t.index ["tag_id", "language"], name: "index_tag_trends_on_tag_id_and_language", unique: true
+  end
+
   create_table "tags", force: :cascade do |t|
     t.string "name", default: "", null: false
     t.datetime "created_at", precision: nil, null: false
@@ -1343,6 +1352,7 @@ ActiveRecord::Schema[7.2].define(version: 2024_11_04_082851) do
   add_foreign_key "statuses_tags", "tags", name: "fk_3081861e21", on_delete: :cascade
   add_foreign_key "tag_follows", "accounts", on_delete: :cascade
   add_foreign_key "tag_follows", "tags", on_delete: :cascade
+  add_foreign_key "tag_trends", "tags", on_delete: :cascade
   add_foreign_key "tombstones", "accounts", on_delete: :cascade
   add_foreign_key "user_invite_requests", "users", on_delete: :cascade
   add_foreign_key "users", "accounts", name: "fk_50500f500d", on_delete: :cascade