Re: Online enabling of checksums

On Thu, Feb 22, 2018 at 9:48 PM, Michael Paquier <michael@paquier.xyz> wrote:
> On Thu, Feb 22, 2018 at 11:24:37AM -0800, Andres Freund wrote:
>> I suspect I'm going to get some grief for this, but I think the time has
>> come to bite the bullet and support changing databases in the same
>> process...
>
> I'd like to see that.  Last time this has been discussed, and Robert
> complained to me immediately when I suggested it, is that this is not
> worth it with the many complications around syscache handling and
> resource cleanup.  It is in the long term more stable to use a model
> where a parent process handles a set of children and decides to which
> database each child should spawn, which is what autovacuum does.

My position is that allowing processes to change databases is a good
idea but (1) it will probably take some work to get correct and (2) it
probably won't be super-fast due to the need to flush absolutely every
bit of state in sight that might've been influenced by the choice of
database.

I also agree with Andres that this email is not very easy to
understand, although my complaint is not so much that I don't see how
the parts relate as that you seem to be contradicting yourself.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company