> Hello,
>
> I had a look for 'backup' on the mailing list archives and strangely
> enough didn't find a message containing the word in admin, general
> and sql mailing lists... I am sure this must have been asked before,
> but still:
>
> Would it be possible to backup a db by just copying the dir struct
> under the PG_DATA or must I absolutely use pg_dump? I am
> using Postgres 7.0. The purpose of the backup is of course to have
> a copy handy if eg the harddrive breaks. As I understand pg_dump
> could be comparatively slower, plus it produces a text format
> dumpfile, which could be kind of large in my db in future.
The pg_dump will in general be smaller. There is a fair amount of overhead
in fitting rows into page boundaries. Also the indexes are not backed up.
Here are some datapoints from my system. I have a datadirectory that is
2.4GB. A pg_dump from that is 800MB (about 400MB compressed). My nightly
dump currently takes about 10 minutes during which the database is not down.
A reload takes 100 minutes including a vacuum analyze. I also sleep better
knowing the data is in a readable text format that I could work with if I
had to.