Question for the developers.

Lists: pgsql-hackers
From: suchindra(at)linuxlabs(dot)com
To: pgsql-hackers(at)postgresql(dot)org
Subject: Question for the developers.
Date: 2003-11-09 00:15:24
Message-ID: Pine.LNX.4.21.0311081905210.30243-100000@ucontrol.mobiledns.com
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Hi,

I am Suchindra Katageri and am working as a Software Engineer at
Linuxlabs, Atlanta, GA.

I am presently working on developing libraries to make postgresql
run on a cluster. I was wondering if it was possible to force Database
writes to stable storage, without messing up with the postgres code.
e.g. force the PostgreSQL to write to stable storage after an INSERT
command.

Thanks in advance.

--
regards,
--suchindra


From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: suchindra(at)linuxlabs(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Question for the developers.
Date: 2003-11-09 00:45:03
Message-ID: 200311090045.hA90j3j17972@candle.pha.pa.us
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suchindra(at)linuxlabs(dot)com wrote:
>
> Hi,
>
> I am Suchindra Katageri and am working as a Software Engineer at
> Linuxlabs, Atlanta, GA.
>
> I am presently working on developing libraries to make postgresql
> run on a cluster. I was wondering if it was possible to force Database
> writes to stable storage, without messing up with the postgres code.
> e.g. force the PostgreSQL to write to stable storage after an INSERT
> command.

For stable storage, you mean disk storage? You need fsync for that,
probably, but we already fsync our write-ahead log (WAL) on every
commit.

--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073


From: Jan Wieck <JanWieck(at)Yahoo(dot)com>
To: suchindra(at)linuxlabs(dot)com
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Question for the developers.
Date: 2003-11-10 15:57:14
Message-ID: 3FAFB55A.2020501@Yahoo.com
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suchindra(at)linuxlabs(dot)com wrote:

> Hi,
>
> I am Suchindra Katageri and am working as a Software Engineer at
> Linuxlabs, Atlanta, GA.
>
> I am presently working on developing libraries to make postgresql
> run on a cluster. I was wondering if it was possible to force Database
> writes to stable storage, without messing up with the postgres code.
> e.g. force the PostgreSQL to write to stable storage after an INSERT
> command.

I don't see how that would help you very far.

PostgreSQL holds disk buffers in a shared memory cache. And unless you
modify that cache, it would not read from the file again if it thinks it
knows the content already. How do you intend to remove pages from that
shared buffer cache at the time, another cluster member modifies the
same logical page?

Jan

--
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# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
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