Re: Rollback in Postgres

In addition to allowing you to read old data, Flashback will allow you to rollback to a point in time, including returning a single table to a specific state. Flashback database is like PITR without the log files.

It started in 9i and improved dramatically in 10g. 11g has made additional improvements.

http://download.oracle.com/docs/cd/B19306_01/backup.102/b14192/intro007.htm

http://download.oracle.com/docs/cd/B28359_01/backup.111/b28270/rcmflash.htm

Lewis R Cunningham

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--- On Fri, 7/11/08, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:

> From: Simon Riggs <simon(at)2ndquadrant(dot)com>
> Subject: Re: [SQL] Rollback in Postgres
> To: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
> Cc: "samantha mahindrakar" <sam(dot)mahindrakar(at)gmail(dot)com>, pgsql-sql(at)postgresql(dot)org
> Date: Friday, July 11, 2008, 2:58 PM
> On Fri, 2008-07-11 at 11:21 -0600, Scott Marlowe wrote:
> > rollback after commit
>
> Are you sure?
>
> Personally I don't think its viable. If it really does
> that it will
> would also need to rollback all transactions whose changes
> depend upon
> the earlier transaction. It would also need to track
> transactions that
> read data changed by an earlier transaction and then makes
> changes to
> the database. It's got no way to track that without
> extensive and costly
> additional infrastructure, since after transaction commit
> row locking
> information can be cleaned up by read-only transactions
> accessing those
> changed data blocks.
>
> Flashback query allows reading data as it was at a certain
> point in the
> past. We might one day provide that, but undoing individual
> transactions
> isn't ever going to be feasible, without unknowable
> risk.
>
> Not jumping on you, just think their marketing is ahead of
> the reality.
>
> --
> Simon Riggs www.2ndQuadrant.com
> PostgreSQL Training, Services and Support
>
>
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