On Sun, Apr 30, 2006 at 12:33:04PM +0200, Martijn van Oosterhout wrote: > On Sat, Apr 29, 2006 at 07:05:35PM -0700, Steve Atkins wrote: > > >Just kidding... once you delete your records... they are gone. > > > > That's.... not true. > > > > Deleted (or modified) records don't go away until the space > > they use is recycled by the VACUUM command. > > Well yes, but with autovacuum you don't know when that might be. > > > However, there's no support in postgresql for any sort of > > "time travel", including viewing deleted tuples. The data > > is there on the disk, but there is no clean way to view it > > via the database. > > Well, there is a timetravel module which you can enable per table. Just > showing deleted records in general doesn't work well because it > violates all sorts of constraints. If you show deleted records, all of > a sudden your unique indexes arn't unique anymore. Timetravel is > expensive though, which is why it's not by default. There is? The only time travel capability I know of is http://www.varlena.com/GeneralBits/122.php. There is also the idea of having vacuum move old tuples to some form of secondary storage instead of sending them to the bit-bucket. An interesting alternative would be to allow for starting a transaction that uses a different XID for reading data than what it would normally use. Provided vacuum hasn't nuked anything that old you should theoretically be able to get a consistent view of data, excluding some things like TRUNCATE. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461
