Re: Keepalive for max_standby_delay - Mailing list pgsql-hackers

From Greg Stark
Subject Re: Keepalive for max_standby_delay
Date
Msg-id AANLkTinziZwRWdTdAnc7XiaOr0DYuY56GX47shmST5s_@mail.gmail.com
Whole thread Raw
In response to Re: Keepalive for max_standby_delay  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Thu, Jun 3, 2010 at 4:34 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> The data keeps coming in and getting dumped into the slave's pg_xlog.
> walsender/walreceiver are not at all tied to the slave's application
> of WAL.  In principle we could have the code around max_standby_delay
> notice just how far behind it's gotten and adjust the delay tolerance
> based on that; but I think designing a feedback loop for that is 9.1
> material.

Er, no. In that case my first concern was misguided. I'm happy there's
no feedback loop -- my fear was that there was and it would mean the
"time received" could be decoupled from the time the wal was
generated. But as you describe it then the time received might be
slightly delayed from the time the wal was generated but to some
constant degree -- not in a way that will be influenced by the log
application being blocked on the slave.

--
greg


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