Re: Streaming a base backup from master

On Sat, Sep 4, 2010 at 9:42 AM, Greg Stark <gsstark@mit.edu> wrote:
> *However* I tihnk you're all headed in the wrong direction here. I
> don't think rsync is what anyone should be doing with their backups at
> all. It still requires scanning through *all* your data even if you've
> only changed a small percentage (which it seems is the use case you're
> concerned about) and it results in corrupting your backup while the
> rsync is in progress and having a window with no usable backup. You
> could address that with rsync --compare-dest but then you're back to
> needing space and i/o for whole backups every time even if you're only
> changing small parts of the database.

It depends.  If the use case is "I accidentally (or purposefully but
temporarily) started up my slave as a master, and now I want it to go
back to having it be the master" or "I lost the WAL files I need to
roll this base backup forward (perhaps because wal_keep_segments
wasn't set high enough)", rsync is what you need.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company