From a6e9f4f44b671f60ddb0ea2b5545c67352fc139c Mon Sep 17 00:00:00 2001
From: Guo Xiang Tan <tgx_world@hotmail.com>
Date: Tue, 17 Jul 2018 10:59:48 +0800
Subject: [PATCH] FIX: DROP NOT NULL instead of changing all the rows in the
 table.

```
change_column :topic_views, :ip_address, :inet, null: true
```

translates to

```
"ALTER TABLE \"topic_views\" ALTER COLUMN \"ip_address\" TYPE inet"
```

which locks the whole table while the migration is taking place.
---
 .../20180521175611_change_indexes_topic_view_item.rb   |  7 -------
 ...17025038_drop_not_null_ip_address_on_topic_views.rb | 10 ++++++++++
 2 files changed, 10 insertions(+), 7 deletions(-)
 create mode 100644 db/migrate/20180717025038_drop_not_null_ip_address_on_topic_views.rb

diff --git a/db/migrate/20180521175611_change_indexes_topic_view_item.rb b/db/migrate/20180521175611_change_indexes_topic_view_item.rb
index 97f5afe8432..21300d91f22 100644
--- a/db/migrate/20180521175611_change_indexes_topic_view_item.rb
+++ b/db/migrate/20180521175611_change_indexes_topic_view_item.rb
@@ -1,12 +1,5 @@
 class ChangeIndexesTopicViewItem < ActiveRecord::Migration[5.1]
   def up
-    begin
-      Migration::SafeMigrate.disable!
-      change_column :topic_views, :ip_address, :inet, null: true
-    ensure
-      Migration::SafeMigrate.enable!
-    end
-
     remove_index :topic_views,
       column: [:ip_address, :topic_id],
       name: :ip_address_topic_id_topic_views,
diff --git a/db/migrate/20180717025038_drop_not_null_ip_address_on_topic_views.rb b/db/migrate/20180717025038_drop_not_null_ip_address_on_topic_views.rb
new file mode 100644
index 00000000000..34288629612
--- /dev/null
+++ b/db/migrate/20180717025038_drop_not_null_ip_address_on_topic_views.rb
@@ -0,0 +1,10 @@
+class DropNotNullIpAddressOnTopicViews < ActiveRecord::Migration[5.2]
+  def change
+    begin
+      Migration::SafeMigrate.disable!
+      change_column_null :topic_views, :ip_address, true
+    ensure
+      Migration::SafeMigrate.enable!
+    end
+  end
+end