From 7fbc1c1b52f5e212f3980269fe9e5bfab1bb8e8e Mon Sep 17 00:00:00 2001
From: Brett Cassette <brett@instacart.com>
Date: Fri, 1 Jul 2016 12:48:47 -0700
Subject: [PATCH] Add Redshift adapter (#133)

---
 Gemfile                |  1 +
 README.md              |  2 +-
 Rakefile               |  6 +++++-
 lib/groupdate/magic.rb | 19 +++++++++++++++++++
 test/redshift_test.rb  | 18 ++++++++++++++++++
 test/test_helper.rb    | 23 +++++++++++++++++++++--
 6 files changed, 65 insertions(+), 4 deletions(-)
 create mode 100644 test/redshift_test.rb

diff --git a/Gemfile b/Gemfile
index a6242c4..72912d8 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,3 +4,4 @@ source "https://rubygems.org"
 gemspec
 
 gem "activerecord", "~> 4.2.0"
+gem "activerecord4-redshift-adapter", "~> 0.2.0"
diff --git a/README.md b/README.md
index 9158431..e5ac722 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,7 @@ The simplest way to group by:
 
 Works with Rails 3.1+
 
-Supports PostgreSQL and MySQL, plus arrays and hashes
+Supports PostgreSQL, MySQL, and Redshift, plus arrays and hashes
 
 [![Build Status](https://travis-ci.org/ankane/groupdate.svg?branch=master)](https://travis-ci.org/ankane/groupdate)
 
diff --git a/Rakefile b/Rakefile
index 0e34b52..bafe855 100644
--- a/Rakefile
+++ b/Rakefile
@@ -4,7 +4,7 @@ require "rake/testtask"
 task default: :test
 Rake::TestTask.new do |t|
   t.libs << "test"
-  t.pattern = "test/**/*_test.rb"
+  t.test_files = FileList["test/**/*_test.rb"].exclude(/redshift/)
 end
 
 namespace :test do
@@ -16,4 +16,8 @@ namespace :test do
     t.libs << "test"
     t.pattern = "test/mysql_test.rb"
   end
+  Rake::TestTask.new(:redshift) do |t|
+    t.libs << "test"
+    t.pattern = "test/redshift_test.rb"
+  end
 end
diff --git a/lib/groupdate/magic.rb b/lib/groupdate/magic.rb
index 3b61b3f..af6b299 100644
--- a/lib/groupdate/magic.rb
+++ b/lib/groupdate/magic.rb
@@ -77,6 +77,25 @@ module Groupdate
           else
             ["(DATE_TRUNC('#{field}', (#{column}::timestamptz - INTERVAL '#{day_start} second') AT TIME ZONE ?) + INTERVAL '#{day_start} second') AT TIME ZONE ?", time_zone, time_zone]
           end
+        when "Redshift"
+          case field
+          when :day_of_week # Sunday = 0, Monday = 1, etc.
+            ["EXTRACT(DOW from CONVERT_TIMEZONE(?, #{column}::timestamp) - INTERVAL '#{day_start} second')::integer", time_zone]
+          when :hour_of_day
+            ["EXTRACT(HOUR from CONVERT_TIMEZONE(?, #{column}::timestamp) - INTERVAL '#{day_start} second')::integer", time_zone]
+          when :day_of_month
+            ["EXTRACT(DAY from CONVERT_TIMEZONE(?, #{column}::timestamp) - INTERVAL '#{day_start} second')::integer", time_zone]
+          when :month_of_year
+            ["EXTRACT(MONTH from CONVERT_TIMEZONE(?, #{column}::timestamp) - INTERVAL '#{day_start} second')::integer", time_zone]
+          when :week # start on Sunday, not Redshift default Monday
+            # Redshift does not return timezone information; it
+            # always says it is in UTC time, so we must convert
+            # back to UTC to play properly with the rest of Groupdate.
+            #
+            ["CONVERT_TIMEZONE(?, 'Etc/UTC', DATE_TRUNC(?, CONVERT_TIMEZONE(?, #{column}) - INTERVAL '#{week_start} day' - INTERVAL '#{day_start} second'))::timestamp + INTERVAL '#{week_start} day' + INTERVAL '#{day_start} second'", time_zone, field, time_zone]
+          else
+            ["CONVERT_TIMEZONE(?, 'Etc/UTC', DATE_TRUNC(?, CONVERT_TIMEZONE(?, #{column}) - INTERVAL '#{day_start} second'))::timestamp + INTERVAL '#{day_start} second'", time_zone, field, time_zone]
+          end
         else
           raise "Connection adapter not supported: #{adapter_name}"
         end
diff --git a/test/redshift_test.rb b/test/redshift_test.rb
new file mode 100644
index 0000000..c7933ee
--- /dev/null
+++ b/test/redshift_test.rb
@@ -0,0 +1,18 @@
+require_relative "test_helper"
+
+class TestRedshift < Minitest::Test
+  include TestGroupdate
+  include TestDatabase
+
+  def setup
+    super
+    @@setup ||= begin
+      abort("REDSHIFT_URL environment variable must be set in order to run tests") unless ENV["REDSHIFT_URL"].present?
+
+      ActiveRecord::Base.establish_connection(ENV["REDSHIFT_URL"])
+
+      create_redshift_tables
+      true
+    end
+  end
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 760e303..88020f8 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -49,6 +49,22 @@ def create_tables
   end
 end
 
+def create_redshift_tables
+  ActiveRecord::Migration.verbose = false
+
+  if ActiveRecord::Migration.table_exists?(:users)
+    ActiveRecord::Migration.drop_table(:users, force: :cascade)
+  end
+
+  if ActiveRecord::Migration.table_exists?(:posts)
+    ActiveRecord::Migration.drop_table(:posts, force: :cascade)
+  end
+
+  ActiveRecord::Migration.execute "CREATE TABLE users (id INT IDENTITY(1,1) PRIMARY KEY, name VARCHAR(255), score INT, created_at DATETIME, created_on DATE);"
+
+  ActiveRecord::Migration.execute "CREATE TABLE posts (id INT IDENTITY(1,1) PRIMARY KEY, user_id INT REFERENCES users, created_at DATETIME);"
+end
+
 module TestDatabase
   def test_zeros_previous_scope
     create_user "2013-05-01"
@@ -332,8 +348,11 @@ module TestDatabase
         created_on: created_at ? Date.parse(created_at) : nil
       )
 
-    # hack for MySQL adapter
-    # user.update_attributes(created_at: nil, created_on: nil) if created_at.nil?
+    # hack for Redshift adapter, which doesn't return id on creation...
+    user = User.last if user.id.nil?
+
+    # hack for MySQL & Redshift adapters
+    user.update_attributes(created_at: nil, created_on: nil) if created_at.nil?
 
     user
   end
--
libgit2 0.21.0