Re: Hot Standby query cancellation and Streaming Replication integration

Aidan Van Dyk wrote:
> Would we (ya, the royal we) be willing to say that if you want the
> benifit of removing the MVCC overhead of long-running queries you need
> to run PITR backup/archive recovery, and if you want SR, you get a
> closed-loop master-follows-save-xmin behaviour?
>   

To turn that question around a little, I think it's reasonable to say 
that closed-loop master-follows-slave-xmin behavior is only practical to 
consider implementing with SR--and even there, it should be optional 
rather than required until there's more field experience on the whole 
thing.  Whether it's the default or not could take a bit of debate to 
sort out too.

If you think of it in those terms, the idea that "you need to run PITR 
backup/archive recovery" to not get that behavior isn't an important 
distinction anymore.  If you run SR with the option enabled you could 
get it, any other setup and you won't.

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us