Re: time-delayed standbys

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: time-delayed standbys
Date: 2011-06-30 03:23:58
Message-ID: BANLkTimrDU3zuRU5KEHbYWf7we3qVttEoQ@mail.gmail.com
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On Thu, Jun 30, 2011 at 10:56 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>> Nope, it gets stuck and stops there.  Replay doesn't advance unless you
>> can somehow clear out some space manually; if the disk is full, the disk
>> is full, and PostgreSQL doesn't remove WAL files without being able to
>> write files first.
>>
>> Manual (or scripted) intervention is always necessary if you reach disk
>> 100% full.
>
> Wow, that's a pretty crappy failure mode... but I don't think we need
> to fix it just on account of this patch.  It would be nice to fix, of
> course.

Yeah, we need to fix that as a separate patch. The difficult point is that
we cannot delete WAL files until we replay the checkpoint record and
restartpoint occurs. But, if the disk is full, there would be no space to
receive the checkpoint record, so we cannot WAL files infinitely.

Regards,

--
Fujii Masao
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center

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