From: Jan Wieck <JanWieck@Yahoo.com>
To: Greg Stark <gsstark@mit.edu>
Cc: pgsql-hackers@postgresql.org
Subject: Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint
Date: Mon, 09 Feb 2004 15:41:07 -0500
Message-ID: <4027F063.8020506@Yahoo.com> (raw)
In-Reply-To: <87r7x4m5uy.fsf@stark.xeocode.com>
References: <200402080144.i181ija15739@candle.pha.pa.us>
<40279A25.6020600@Yahoo.com>
<87r7x4m5uy.fsf@stark.xeocode.com>
Greg Stark wrote:
> Jan Wieck <JanWieck@Yahoo.com> writes:
>
>> The whole sync() vs. fsync() discussion is in my opinion nonsense at this
>> point. Without the ability to limit the amount of files to a reasonable number,
>> by employing tablespaces in the form of larger container files, the risk of
>> forcing excessive head movement is simply too high.
>
> I don't think there was any suggestion of conflating tablespaces with
> implementing a filesystem in postgres.
>
> Tablespaces are just a database entity that database stored objects like
> tables and indexes are associated to. They group database stored objects and
> control the storage method and location.
>
> The existing storage mechanism, namely a directory with a file for each
> database object, is perfectly adequate and doesn't have to be replaced to
> implement tablespaces. All that's needed is that the location of the directory
> be associated with the "tablespace" of the object rather than be a global
> constant.
>
> Implementing an Oracle-style filesystem is just one more temptation to
> reimplement OS services in the database. Personally I think it's an awful
> idea. But even if postgres did it as an option, it wouldn't necessarily have
> anything to do with tablespaces.
>
Doing this is not just what you call it. In a system with let's say 500
active backends on a database with let's say 1000 things that are
represented as a file, you'll need half a million virtual file descriptors.
Jan
--
#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me. #
#================================================== JanWieck@Yahoo.com #
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To: pgsql-hackers@postgresql.org
Cc: JanWieck@Yahoo.com, gsstark@mit.edu
Subject: Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint
In-Reply-To: <4027F063.8020506@Yahoo.com>
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