Re: [PATCH] pg_isready (was: [WIP] pg_ping utility)

2013/1/26 Phil Sorber <phil(at)omniti(dot)com>:
> On Sat, Jan 26, 2013 at 11:53 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>> 2013/1/26 Phil Sorber <phil(at)omniti(dot)com>:
>>> On Sat, Jan 26, 2013 at 4:02 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>>> Hello
>>>>
>>>> We now haw to solve small puppet issue, because our puppets try to
>>>> start server too early, when old instance live still.
>>>>
>>>> Maybe some new parameter - is_done can be useful.
>>>>
>>>
>>> What about something like:
>>> pg_isready; while [ $? -ne 2 ]; do sleep 1; pg_isready; done
>>
>> it is not enough - server is done in a moment, where can be started
>> again - or when we can do safe copy of database data directory.
>>
>
> I guess i am not completely understanding the case you are trying to
> solve. Can you explain a bit further?

We use puppets and due some simplification we cannot to use reload
when configuration is changed. Our puppets has not enough intelligence
to understand when is reload enough and when is restart necessary. So
any change to configuration require restarting postgres. I don't know
why "service restart" are not used. I believe so our puppet guru know
it. It just do sequence STOP:START Now puppets are "smart" and able
to wait for time, when server is ready. But there are missing simple
test if server is really done and I see a error messages related to
too early try to start. So some important feature can be verification
so server is really done.

We can do it with test on pid file now - and probably we will use it.
But I see so this is similar use case (in opposite direction)

Regards

Pavel

>
>> Regards
>>
>> Pavel
>>
>>
>>
>>>
>>> Perhaps with a counter to break out of the loop after some number of attempts.
>>>
>>>> Regards
>>>>
>>>> Pavel
>>>>