It's interesting to know what pg WAL's are:
If they are page level logs, then you theoretically can have a file system
backup - which is fast, reliable, no issues like pg_dump has, i.e. who is
first/last regarding stored procedures/views/triggers, to have users
precreated, etc, etc.
If the are SQL statements which are REPLAYD after pg_dump restore: well, then
file system backup has no chance. The issue is that you are missing index
pages and probably much more.
Regards, Laimis
> -----Original Message-----
> From: John Sidney-Woollett [mailto:johnsw@wardbrook.com]
> Sent: 22. janúar 2004 17:53
> To: Laimutis Nedzinskas
> Cc: johnsw@wardbrook.com
> Subject: RE: [GENERAL] tablespaces a priority for 7.5?
>
>
> lnd@hnit.is said:
> >> (I think) that was the point I was trying to make. Oracle lets you
> >> backup while up and running (using export) OR when offline
> (copying
> >> db files)...
> >
> > Not neccesseraly offline. In oracle you take tablespace in
> backup mode
> > and just use OCOPY(I believe you must watch out that file copy is
> > performed at OS block sizes not smaller than db page size -
> OCOPY does
> > that) to copy files.
> > REDO logs (i.e. WAL logs) will bring copied files in synch.
> > Or one can use RMAN tool which is the same as to copy files
> just it makes
> > book-keeping for backups and discards empty pages from
> backuped file.
>
> You obviously know Oracle better than me - I stand corrected! :)
>
> Actually I was trying to figure out whether the WAL segments
> could be applied to a database rebuilt using a file generated
> by pg_dump. I suspect not, and doesn't that mean that the
> postmaster needs to be stopped to carry out the file system
> level copy of the pg files?
>
> John
>
