README.md in strong_migrations-0.1.0 vs README.md in strong_migrations-0.1.1

@@ -12,38 +12,25 @@
 gem 'strong_migrations'
 ```
 
 ## Dangerous Operations
 
-- adding an index non-concurrently
-- adding a column with a non-null default value
+- adding a column with a non-null default value to an existing table
 - changing the type of a column
 - renaming a table
 - renaming a column
 - removing a column
-- adding a `json` column (Postgres only)
+- adding an index non-concurrently (Postgres only)
+- adding a `json` column to an existing table (Postgres only)
 
 For more info, check out:
 
 - [Rails Migrations with No Downtime](http://pedro.herokuapp.com/past/2011/7/13/rails_migrations_with_no_downtime/)
 - [Safe Operations For High Volume PostgreSQL](https://www.braintreepayments.com/blog/safe-operations-for-high-volume-postgresql/) (if it’s relevant)
 
 ## The Zero Downtime Way
 
-### Adding an index
-
-Add indexes concurrently.
-
-```ruby
-class AddSomeIndexToUsers < ActiveRecord::Migration
-  def change
-    commit_db_transaction
-    add_index :users, :some_index, algorithm: :concurrently
-  end
-end
-```
-
 ### Adding a column with a default value
 
 1. Add the column without a default value
 2. Commit the transaction
 3. Backfill the column
@@ -73,12 +60,10 @@
 end
 ```
 
 ### Renaming or changing the type of a column
 
-There’s no way to do this without downtime.
-
 If you really have to:
 
 1. Create a new column
 2. Write to both columns
 3. Backfill data from the old column to the new column
@@ -86,15 +71,22 @@
 5. Stop writing to the old column
 6. Drop the old column
 
 ### Renaming a table
 
-Same as renaming a column - see above.
+If you really have to:
 
+1. Create a new table
+2. Write to both tables
+3. Backfill data from the old table to new table
+4. Move reads from the old table to the new table
+5. Stop writing to the old table
+6. Drop the old table
+
 ### Removing a column
 
-Tell ActiveRecord to [ignore the column](http://pedro.herokuapp.com/past/2011/7/13/rails_migrations_with_no_downtime/) from its cache.
+Tell ActiveRecord to ignore the column from its cache.
 
 ```ruby
 class User
   def self.columns
     super.reject { |c| c.name == "some_column" }
@@ -102,12 +94,25 @@
 end
 ```
 
 Once it’s deployed, create a migration to remove the column.
 
-### Adding a json column
+### Adding an index (Postgres)
 
-There’s no equality operator for the `json` column type. Replace all calls to `uniq` with a custom scope.
+Add indexes concurrently.
+
+```ruby
+class AddSomeIndexToUsers < ActiveRecord::Migration
+  def change
+    commit_db_transaction
+    add_index :users, :some_index, algorithm: :concurrently
+  end
+end
+```
+
+### Adding a json column (Postgres)
+
+There’s no equality operator for the `json` column type, which causes issues for `SELECT DISTINCT` queries. Replace all calls to `uniq` with a custom scope.
 
 ```ruby
 scope :uniq_on_id, -> { select("DISTINCT ON (your_table.id) your_table.*") }
 ```