From b9e6a89f2216f21c0bec0f59b49190fbe29bf6af Mon Sep 17 00:00:00 2001
From: Petko Bordjukov <bordjukov@gmail.com>
Date: Thu, 13 Oct 2016 04:23:56 +0300
Subject: [PATCH] Introduce a ConflictsForTalk model and db view

---
 app/models/conflicts_for_talk.rb              |  2 ++
 ...61013011420_add_conflicts_for_talk_view.rb | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 app/models/conflicts_for_talk.rb
 create mode 100644 db/migrate/20161013011420_add_conflicts_for_talk_view.rb

diff --git a/app/models/conflicts_for_talk.rb b/app/models/conflicts_for_talk.rb
new file mode 100644
index 0000000..0b554d7
--- /dev/null
+++ b/app/models/conflicts_for_talk.rb
@@ -0,0 +1,2 @@
+class ConflictsForTalk < ApplicationRecord
+end
diff --git a/db/migrate/20161013011420_add_conflicts_for_talk_view.rb b/db/migrate/20161013011420_add_conflicts_for_talk_view.rb
new file mode 100644
index 0000000..9c35a1c
--- /dev/null
+++ b/db/migrate/20161013011420_add_conflicts_for_talk_view.rb
@@ -0,0 +1,19 @@
+CONFLICTS_FOR_TALK_VIEW_SQL = <<EOS
+CREATE VIEW "conflicts_for_talks" AS
+SELECT     DISTINCT("left"."talk_id")              AS "talk_id",
+           COUNT("right"."talk_preference_id") - 1 AS "conflicts"
+FROM       "selected_talks"                        AS "left"
+INNER JOIN "selected_talks"                        AS "right"
+ON         "left"."talk_id" = "right"."talk_id"
+GROUP BY   "left"."id";
+EOS
+
+class AddConflictsForTalkView < ActiveRecord::Migration[5.0]
+  def up
+    execute CONFLICTS_FOR_TALK_VIEW_SQL
+  end
+
+  def down
+    execute 'DROP VIEW "conflicts_for_talks"'
+  end
+end