Chapter 10 part 2 - The binary formats
The three binary formats supported by pg_dump are the custom, the directory and the tar format. The first two can be accessed randomly by the restore program and have the parallel restore support, being the best choice for having a flexible and reliable restore. Before the the 9.3 the only format supporting the parallel restore was the custom. With this version the directory format accepts the -j switch. This feature, combined with the parallel dump seen in 9.