Инициалиазация репозитория

db/migrate/20240716182509_create_versions.rb

@@ -0,0 +1,38 @@
+# This migration creates the `versions` table, the only schema PT requires.
+# All other migrations PT provides are optional.
+class CreateVersions < ActiveRecord::Migration[7.1]
+
+  # The largest text column available in all supported RDBMS is
+  # 1024^3 - 1 bytes, roughly one gibibyte.  We specify a size
+  # so that MySQL will use `longtext` instead of `text`.  Otherwise,
+  # when serializing very large objects, `text` might not be big enough.
+  TEXT_BYTES = 1_073_741_823
+
+  def change
+    create_table :versions do |t|
+      t.string   :item_type, null: false
+      t.bigint   :item_id,   null: false
+      t.string   :event,     null: false
+      t.string   :whodunnit
+      t.text     :object, limit: TEXT_BYTES
+
+      # Known issue in MySQL: fractional second precision
+      # -------------------------------------------------
+      #
+      # MySQL timestamp columns do not support fractional seconds unless
+      # defined with "fractional seconds precision". MySQL users should manually
+      # add fractional seconds precision to this migration, specifically, to
+      # the `created_at` column.
+      # (https://dev.mysql.com/doc/refman/5.6/en/fractional-seconds.html)
+      #
+      # MySQL users should also upgrade to at least rails 4.2, which is the first
+      # version of ActiveRecord with support for fractional seconds in MySQL.
+      # (https://github.com/rails/rails/pull/14359)
+      #
+      # MySQL users should use the following line for `created_at`
+      # t.datetime :created_at, limit: 6
+      t.datetime :created_at
+    end
+    add_index :versions, %i[item_type item_id]
+  end
+end