Vick Khera <vivek at khera.org> writes:
> On Thu, Jan 13, 2011 at 4:13 PM, Christopher Browne
> <cbbrowne at ca.afilias.info> wrote:
>> Behind by...
>>   - >= 5 events
>>   - >= 30 seconds
>>
>
> I like these two.
>
>
>> Other Health Criteria
>> - Is node there?
>> - Is replication set there?
>> - Is subscription active?
>> - Run SQL, fail if ERROR
>
> Doesn't "missing node" or "missing set" generally cause total abort
> already?  Hmm. I guess it could be later in the script after stuff is
> already done.

Well, this feature is rather like a C assert() statement.  I'd think a
good way to use this is to have a script start by declaring what it
needs as cluster configuration; if any of those conditions fail to be
true, it fails without attempting to do any work.

> I worry aboutt "run SQL".  there would probably need to be some
> foot-gun avoidance instructions of stuff not to do.  Perhaps it can
> only be a SELECT (and your fault if you call a function with side
> effects).

I'd be inclined to run the SQL within a read-only transaction, which
would prevent any such shenanigans.
-- 
(reverse (concatenate 'string "ofni.sailifa" "@" "enworbbc"))
Christopher Browne
"Bother,"  said Pooh,  "Eeyore, ready  two photon  torpedoes  and lock
phasers on the Heffalump, Piglet, meet me in transporter room three"