Add pg gem scope_all benchmark

pg/Gemfile

@@ -0,0 +1,15 @@
+source "https://rubygems.org"
+
+module ::Kernel
+  def pg_master?
+    ENV["PG_MASTER"] == '1'
+  end
+end
+
+if pg_master?
+  gem 'pg', github: 'ged/ruby-pg'
+else
+  gem 'pg', path: '/pg'
+end
+
+gem 'benchmark-ips', '~> 2.2.0'

pg/benchmarks/pg_scope_all.rb

@@ -0,0 +1,24 @@
+require 'bundler/setup'
+require 'pg'
+require_relative 'support/benchmark_pg'
+
+conn = PG.connect(
+  host: ENV.fetch("HOST", "localhost"),
+  port: ENV.fetch("PORT", "5432"),
+  dbname: ENV.fetch("DB_NAME", "rubybench"),
+  user: ENV.fetch("DB_USER", "postgres"),
+  password: ENV.fetch("DB_PASSWORD", "postgres")
+)
+
+conn.exec("DROP TABLE IF EXISTS users;")
+conn.exec("CREATE TABLE users ( name varchar(255), email varchar(255), created_at timestamp, updated_at timestamp );")
+
+1000.times do
+  conn.exec("INSERT INTO users VALUES ('Lorem ipsum dolor sit amet, consectetur adipiscing elit.', 'foobar@email.com');")
+end
+
+Benchmark.pg("raw_pg/postgres_scope_all", time: 5) do
+  str = ""
+  conn.exec("SELECT * FROM users").each_row{ |row| str << "name: #{row[0]} email: #{row[1]}\n" }
+end
+

pg/benchmarks/support/benchmark_pg.rb

@@ -0,0 +1,12 @@
+require 'pg'
+require_relative '../../../support/benchmark_runner'
+
+module Benchmark
+  module PG
+    def pg(label = nil, version: ::PG::VERSION.to_s, time:, disable_gc: true, warmup: 3, &block)
+      Benchmark::Runner.run(label, version: version, time: time, disable_gc: disable_gc, warmup: warmup, &block)
+    end
+  end
+
+  extend Benchmark::PG
+end