POC code to show savepoints from subsequent appends in transaction

Related:
#1108

ruby_event_store-active_record/poc.rb

@@ -0,0 +1,47 @@
+require "bundler/inline"
+
+gemfile do
+  source "https://rubygems.org"
+  gem "ruby_event_store", path: ".."
+  gem "ruby_event_store-active_record", path: "."
+  gem "pg"
+  gem "childprocess"
+  gem "benchmark-ips"
+end
+
+require "ruby_event_store"
+require "ruby_event_store/active_record"
+
+require_relative "../support/helpers/migrator"
+require_relative "../support/helpers/schema_helper"
+
+include SchemaHelper
+establish_database_connection
+drop_database
+load_database_schema
+
+event_store =
+  RubyEventStore::Client.new(
+    repository:
+      RubyEventStore::ActiveRecord::EventRepository.new(
+        serializer: RubyEventStore::NULL
+      )
+  )
+
+mk_event =
+  lambda { RubyEventStore::Event.new(metadata: { event_type: "whatever" }) }
+
+logged_keywords = %w[COMMIT BEGIN SAVEPOINT RELEASE].freeze
+
+log_transaction =
+  lambda do |name, started, finished, unique_id, payload|
+    if logged_keywords.any? { |keyword| payload[:sql].start_with? keyword }
+      puts payload[:sql]
+    end
+  end
+
+ActiveSupport::Notifications.subscribed(log_transaction, /sql/) do
+  ActiveRecord::Base.transaction do
+    100.times { event_store.append(mk_event.call) }
+  end
+end