Re: [HACKERS] make async slave to wait for lsn to be replayed

Andres Freund писал 2018-03-02 03:47:
> On 2018-02-02 19:41:37 +0000, Simon Riggs wrote:
>> On 2 February 2018 at 18:46, Robert Haas <robertmhaas@gmail.com> 
>> wrote:
>> > On Fri, Feb 2, 2018 at 3:46 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> >> In PG11, I propose the following command, sticking mostly to Ants'
>> >> syntax, and allowing to wait for multiple events before it returns. It
>> >> doesn't hold snapshot and will not get cancelled by Hot Standby.
>> >>
>> >> WAIT FOR event [, event ...] options
>> >>
>> >> event is
>> >> LSN value
>> >> TIMESTAMP value
>> >>
>> >> options
>> >> TIMEOUT delay
>> >> UNTIL TIMESTAMP timestamp
>> >> (we have both, so people don't need to do math, they can use whichever
>> >> they have)
>> >
>> > WAIT FOR TIMEOUT sounds a lot like SELECT pg_sleep_for(), and WAIT
>> > UNTIL TIMESTAMP sounds a lot like SELECT pg_sleep_until().
>> 
>> Yes, it sounds very similar. It's the behavior that differs; I read
>> and agreed with yours and Thomas' earlier comments on that point.
>> 
>> As pointed out upthread, the key difference is whether it gets
>> cancelled on Hot Standby and whether you can call it in a non-READ
>> COMMITTED transaction.
> 
> Given that nobody has updated the patch or even discussed doing so, I
> assume this would CF issue should now appropriately be classified as
> returned with feedback?

Hello, I now is preparing the patch over syntax that Simon offered. And 
in few day I will update the patch.
Thank you for your interest in thread.

-- 
Ivan Kartyshov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company