"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. -- Gregory Stark EnterpriseDB http://www.enterprisedb.com Ask me about EnterpriseDB's RemoteDBA services! ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
