AW: physical backup of PostgreSQL

> At 12:13 26/06/00 +0200, Zeugswetter Andreas SB wrote:
> >After further thought I do think that a physical restore of a backup 
> >done with e.g. tar and pg_log as first file of backup does 
> indeed work.
> 
> Even if the file backup occurs in the middle of a vacuum?

I guess not, since at vacuum time the rows are moved inside the pages,
but that does not seem like a real world limitation to me.

> I like the idea of a non-SQL-based backup method, but it 
> would be nice to
> see some kind of locking being done to ensure that the backup 
> is a valid
> database snapshot. Can some kind of consistent page dump be 
> done? (Rather
> than a file copy)

Yes, it is the current smgr that makes any locking obsolete.

> I believe Vadim's future plans involve reuse of data pages - 
> would this
> have an impact on backup integrity?

Yes.

> My experience with applying journals to restored databases 
> suggests that
> the journals need to be applied to a 'known' state of the database -
> usually a snapshot as of a certain TX Seq No.

Yes, if Vadim changes things to overwrite. 
Of course we could have a db mode where nothing is overwritten,
since we have the code for that.

Andreas