Ecto.Migration.drop_if_exists

You're seeing just the function drop_if_exists, go back to Ecto.Migration module for more information.

drop_if_exists(index_or_table)

Drops a table or index if it exists.

Does not raise an error if the specified table or index does not exist.

drop_if_exists index("posts", [:name])
drop_if_exists table("posts")