Add Creating Indexes With Ecto as an elixir til

elixir/creating-indexes-with-ecto.md

@@ -0,0 +1,19 @@
+# Creating Indexes With Ecto
+
+Using indexes in the right places within relational databases is a great way
+to speed up queries and ensure data integrity.
+
+To add a basic index in an Ecto migration, use `Ecto.Migration.index\2`:
+
+```elixir
+create index(:users, [:email])
+```
+
+Creating a composite index doesn't require jumping through any hoops; just
+put the relevant column names in the list:
+
+```elixir
+create index(:posts, [:user_id, :title])
+```
+
+See `h Ecto.Migration.index` for more details.