On Sun, 2008-01-20 at 15:11 +0000, Gregory Stark wrote: > "Simon Riggs" <[EMAIL PROTECTED]> writes: > > > On Sat, 2008-01-12 at 18:46 +0000, Gregory Stark wrote: > > > >> To do something like that the user would have to create a prepared > >> transaction > >> to save the snapshot. I think that makes sense though since effectively > >> it's > >> just requiring that the user explicitly do what would otherwise be a hidden > >> implicit requirement -- that the user do something to hold globalxmin back > >> to > >> avoid having the snapshots expire. > > > > This is a good idea which I will want to develop in the future, not yet > > though. > > I didn't mean this as an additional feature. I'm talking about how users would > use the two very different proposed interfaces. > > In your version the user can save the actual snapshot somewhere and then use > it later. He'll presumably get an error if the snapshot is no longer usable > and there's no way for him to protect it and guarantee it's still usable. > > In Tom's version the user can only copy the snapshot from some other running > session. It's necessarily still valid because the session is using it. But if > the user wants to save it for later he'll have to create a session (or > prepared transaction) to hold the snapshot.
OK, misunderstanding. "My version" is being done now, so we can use it now; it will be published as BSD licenced open source software, but as yet seems unlikely to ever be part of a main distribution of Postgres. It will probably be published on pgfoundry, though possibly elsewhere also. I don't take credit for the general idea, but I am responsible for the idea to do this now as an external function. I prefer this done in the backend in the long term, much safer, which we are agreed upon. I'll come back to that so we get it into 8.4. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
