Backing up PostgreSQL

Question

I'm a new to PostgreSQL and I'm looking to backup the database. I understand that there are 3 methods pg_dump, snapshot and copy and using WAL. Which one do you suggest for full backup of the database? If possible, provide code snippets.

• IMSoP: There's a lot of context missing here, notably why you need a C/C++ program: are you trying to build backup automation into some existing maintenance application? Or implement some additional functionality on top of the existing tools? As it stands, the only way to answer is a broad discussion of the existing tools, which isn't the kind of question encouraged here.

Answer 1

It depends a lot more on your operational requirements than anything else.

All three will require shelling out to an external program. libpq doesn't provide those facilities directly; you'll need to invoke the pg_basebackup or pg_dump via execv or similar.

All three have different advantages.

Atomic snapshot based backups are useful if the filesystem supports them, but become useless if you're using tablespaces since you then need a multivolume atomic snapshot - something most systems don't support. They can also be a pain to set up.

pg_dump is simple and produces compact backups, but requires more server resources to run and doesn't support any kind of point-in-time recovery or incremental backup.

pg_basebackup + WAL archiving and PITR is very useful, and has a fairly low resource cost on the server, but is more complex to set up and manage. Proper backup testing is imperative.

I would strongly recommend allowing the user to control the backup method(s) used. Start with pg_dump since you can just invoke it as a simple command line and manage a single file. Use the -Fc mode and pg_restore to restore it where needed. Then explore things like configuring the server for WAL archiving and PITR once you've got the basics going.