Horton

Re: Streaming replication and WAL archive interactions

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: hlinnaka <hlinnaka@iki.fi>
Cc: Michael Paquier <michael.paquier@gmail.com>, Venkata Balaji N <nag1010@gmail.com>, Andres Freund <andres@anarazel.de>, Fujii Masao <masao.fujii@gmail.com>, Borodin Vladimir <root@simply.name>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2015-04-22T20:58:31Z
Lists: pgsql-hackers 
On Wed, Apr 22, 2015 at 3:34 PM, Heikki Linnakangas <hlinnaka@iki.fi> wrote:
> On 04/22/2015 10:21 PM, Robert Haas wrote:
>> On Wed, Apr 22, 2015 at 3:01 PM, Heikki Linnakangas <hlinnaka@iki.fi>
>> wrote:
>>> For example, imagine that perform point-in-time recovery to WAL position
>>> 0/1237E568, on timeline 1. That falls within segment
>>> 000000010000000000000012. Then we end recovery, and switch to timeline 2.
>>> After the switch, and some more WAL-logged actions, we'll have these
>>> files
>>> in pg_xlog:
>>>
>>> 000000010000000000000011
>>> 000000010000000000000012
>>> 000000020000000000000012
>>> 000000020000000000000013
>>> 000000020000000000000014
>>
>>
>> Is the 000000010000000000000012 file a "partial" segment of the sort
>> you're proposing to no longer achive?
>
> If you did pure archive recovery, with no streaming replication involved,
> then no. If it was created by streaming replication, and the replication had
> not filled the whole segment yet, then yes, it would be a partial segment.

Why the difference?

-- 
Robert Haas
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