To: pgsql-hackers@postgresql.org
Subject: Re: [pgsql-hackers-win32] Sync vs. fsync during checkpoint
References: <200402080144.i181ija15739@candle.pha.pa.us>
	<40279A25.6020600@Yahoo.com>
In-Reply-To: <40279A25.6020600@Yahoo.com>
From: Greg Stark <gsstark@mit.edu>
Organization: The Emacs Conspiracy; member since 1992
Date: 09 Feb 2004 14:04:53 -0500
Message-ID: <87r7x4m5uy.fsf@stark.xeocode.com>
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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.

-- 
greg