Creating Indexes With Ecto
Using indexes in the right places within relational databases is a great way to speed up queries.
To add a basic index in an Ecto migration, use
create index(:users, [:email])
Creating a composite index doesn't require jumping through any hoops; just put the relevant column names in the list:
create index(:posts, [:user_id, :title])
h Ecto.Migration.index for more details.