Re: pgsql: Fast promote mode skips checkpoint at end of recovery.

Simon Riggs <simon(at)2ndQuadrant(dot)com> wrote:

>On 29 January 2013 16:27, Fujii Masao <masao(dot)fujii(at)gmail(dot)com> wrote:
>> On Tue, Jan 29, 2013 at 9:07 AM, Simon Riggs <simon(at)2ndquadrant(dot)com>
>wrote:
>>> Fast promote mode skips checkpoint at end of recovery.
>>> pg_ctl promote -m fast will skip the checkpoint at end of recovery
>so that we
>>> can achieve very fast failover when the apply delay is low. Write
>new WAL record
>>> XLOG_END_OF_RECOVERY to allow us to switch timeline correctly for
>downstream log
>>> readers. If we skip synchronous end of recovery checkpoint we
>request a normal
>>> spread checkpoint so that the window of re-recovery is low.
>>
>> When I tested this feature, I encountered the following FATAL
>message.
>>
>> FATAL: highest timeline 1 of the primary is behind recovery
>timeline 2
>>
>> Is this an intentional behavior or bug?
>
>Tough one that.
>
>> What I did in my test is:
>>
>> 1. Set up one master (A), one standby (B), one cascade standby (C)
>> 2. After running pgbench -i -s 10, I promoted the standby (B) with
>fast mode
>> 3. Then, I shut down the server (B) with immediate mode after it has
>been
>> brought up to the master before end-of-recovery checkpoint has
>not been
>> completed.
>> 4. Restart the server (B).
>> 5. After the standby (C) established the replication connection with
>(B),
>> I got the above FATAL messages repeatedly.
>
>Where do you get the errors, which server? The above doesn't contain a
>promote command, so how does this make it fail.
>
>Please show me the test case in more detail.
>
>> Promoting (B) increments the timeline ID to 2 and generates the
>timeline
>> history file. But after restarting (B), its timeline ID is reset to 1
>> unexpectedly.
>> This seems to be the cause of the problem.
>>
>> To address this problem, we should switch to new timeline ID whenever
>> we read the XLOG_END_OF_RECOVERY even if it's a crash recovery?
>
>We do. Do you see a problem with that code? There is no conditional
>recovery.

Hi,

Could you please move this to -hackers, for archives' sake?

Regards, Devrim
--
Devrim Gündüz