Re: Transaction Snapshots and Hot Standby

> I think that enabling long-running queries this way is both
> low-hanging
> fruit (or at least medium-height-hanging ;) ) and also consistent to
> PostgreSQL philosophy of not replication effort. As an example we trust
> OS's file system cache and don't try to write our own.

I have again questions (unfortunately I only have questions usually):

* how will the buffers keep 2 different versions of the same page ?
* how will you handle the creation of snapshots ? I guess there's no portable and universal API for that (just
guessing),or there is some POSIX thing which is supported or not by the specific FS ? So if the FS is not supporting
it,you skip the snapshot step ? And if there's no universal API, will it be handled by plugins providing a specified
APIfor snapshotting the FS ?
 

I hope my continuous questioning is not too annoying...

Cheers,
Csaba.