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Re: Updated version of pg_receivexlog

From: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Updated version of pg_receivexlog
Date: 2011-10-27 09:25:59
Message-ID: CAHGQGwG==wdDrD9w045k4umWRhSto5_Jsqr7jYmgjBAsHC8SQw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Thu, Oct 27, 2011 at 5:18 PM, Magnus Hagander <magnus(at)hagander(dot)net> wrote:
> Not sure I follow. When we arrive at PQgetCopyData() there should be
> nothing buffered, and if the end of stream happens there it returns
> -1, and we exit, no? So where is the data that's lost?
>
> I do realize we don't actually fsync() and close() in this case - is
> that what you are referring to? But the data should already have been
> write()d, so it should still be there, no?

Oh, right. Hmm.. xlogdump might be the cause.

Though I've not read the code of xlogdump, I wonder if it gives up
outputting the contents of WAL file when it finds a partial WAL page...
This strikes me that recovery code has the same problem. No?
IOW, when a partial WAL page is found during recovery, I'm afraid
that page would not be replayed though it contains valid data.

Regards,

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

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Subject: Re: Hot Backup with rsync fails at pg_clog if under load
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