在数据加载之前或之后创建Oracle SQL索引更好吗？

I need to populate a table with a huge amount of data (many hours loading) on an Oracle database, and i was wondering which would be faster, to create an index on the table before loading it or after loading it. I initially thought that inserting on an indexed table is penalized, but then if i create the index with the full table, it will take a lot of time. Which is best?I need to populate a table with a huge amount o