Re: BUG #8192: On very large tables the concurrent update with vacuum lag the hot_standby replica - Mailing list pgsql-bugs

From Jeff Janes
Subject Re: BUG #8192: On very large tables the concurrent update with vacuum lag the hot_standby replica
Date
Msg-id CAMkU=1wYV+8ENM-mYSKTWnB7+6wvxONWv-O_1WPc3njicChM-Q@mail.gmail.com
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In response to Re: BUG #8192: On very large tables the concurrent update with vacuum lag the hot_standby replica  (Federico Campoli <federico@brandwatch.com>)
List pgsql-bugs
On Tue, Jun 4, 2013 at 5:57 AM, Federico Campoli <federico@brandwatch.com>wrote:

>
> I'm sorry, just guessing it could be a loop.
> The read remains stuck on the same segment.
> On my testbox I have at least 1 minute to 20 Mb/s.
> On the live system the peak is 124 Mb/s for 2 to 3 minutes without any
> progress in the wal reply.
>
> I've attached the part of postgresql's log with debug2  from my sandbox
> when that happens.
>

It looks like it is making progress, just very slowly.  Basically I think
every WAL record that needs it to be replayed triggers the random read of
some data block which is not already cached on the standby.



> In warm standby everything is fine no lag at all.
>

OK, then I don't think I can reproduce it.  The spiky replay I see is the
same whether the standby is hot or warm.


Cheers,

Jeff

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