Re: Support for N synchronous standby servers - take 2

On 15 July 2015 at 12:25, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote:

> Simon Riggs wrote:
>
> > JSON seems the most sensible format for the string. Inventing a new one
> > doesn't make sense. Most important for me is the ability to
> > programmatically manipulate/edit the config string, which would be harder
> > with a new custom format.
>
> Do we need to keep the value consistent across all the servers in the
> flock? If not, is the behavior halfway sane upon failover?
>

Mostly, yes. Which means it doesn't change much, so config data is OK.

> If we need the DBA to keep the value in sync manually, that's going to
> be a recipe for trouble. Which is going to bite particularly hard
> during those stressing moments when disaster strikes and things have to
> be done in emergency mode.
>

Manual config itself is the recipe for trouble, not this particular
setting. There are already many other settings that need to be the same on
all nodes for example. Nothing here changes that. This is just an
enhancement of the current technology.

For the future, a richer mechanism for defining nodes and their associated
metadata is needed for logical replication and clustering. That is not what
is being discussed here though, nor should we begin!

--
Simon Riggs http://www.2ndQuadrant.com/
<http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services