Handling various formats

So far, you have seen that pg_dump can be used to create text files. The problem is that a text file can only be replayed completely. If you have saved an entire database, you can only replay the entire thing. In many cases, this is not what you want. Therefore, PostgreSQL has additional formats that also offer more functionality.

At this point, four formats are supported:

-F, --format=c|d|t|p  output file  format (custom, directory, tar, plain  text  (default))

You have already seen plain, which is just normal text. On top of that, you can use a custom format. The idea behind a custom format is to have a compressed dump, including a table of contents. Here are two ways to create a custom format dump:

[hs@linuxpc ~]$ pg_dump -Fc test > /tmp/dump.fc[hs@linuxpc ~]$ pg_dump -Fc test -f /tmp/dump.fc

In addition to the table of contents, the compressed dump has one more advantage: it is a lot smaller. The rule of thumb is that a custom format dump is around 90% smaller...