Re: Support for N synchronous standby servers - take 2 - Mailing list pgsql-hackers

From Simon Riggs
Subject Re: Support for N synchronous standby servers - take 2
Date
Msg-id CANP8+j+1op2Vi_GRe4LY6toz+qMwBT6TaY3PgARvUnowg72joA@mail.gmail.com
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In response to Re: Support for N synchronous standby servers - take 2  (Alvaro Herrera <alvherre@2ndquadrant.com>)
List pgsql-hackers
On 15 July 2015 at 12:25, Alvaro Herrera <alvherre@2ndquadrant.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/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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