Re: Sync Rep v19

On Sat, Mar 5, 2011 at 7:49 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Sat, 2011-03-05 at 07:24 -0500, Robert Haas wrote:
>> On Sat, Mar 5, 2011 at 6:04 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> > It is documented that the selection of standby from a set of similar
>> > priorities is indeterminate. Users don't like it, they can change it.
>>
>> That doesn't seem like a good argument to *change* the synchronous
>> standby once it's already set.
>
> If the order is arbitrary, why does it matter if it changes?
>
> The user has the power to specify a sequence, yet they have not done so.
> They are told the results are indeterminate, which is accurate. I can
> add the words "and may change as new standbys connect" if that helps.

I just don't think that's very useful behavior. Suppose I have a
master and two standbys. Both are local (or both are remote with
equally good connectivity). When one of the standbys goes down, there
will be a hiccup (i.e. transactions will block trying to commit) until
that guy falls off and the other one takes over. Now, when he comes
back up again, I don't want the synchronous standby to change again;
that seems like a recipe for another hiccup. I think "who the current
synchronous standby is" should act as a tiebreak.

--
Robert Haas
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