Re: Improve lseek scalability v3

From: Stephen Frost <sfrost(at)snowman(dot)net>
To: Benjamin LaHaise <bcrl(at)kvack(dot)org>
Cc: Andres Freund <andres(at)anarazel(dot)de>, Matthew Wilcox <matthew(at)wil(dot)cx>, Andi Kleen <andi(at)firstfloor(dot)org>, viro(at)zeniv(dot)linux(dot)org(dot)uk, linux-fsdevel(at)vger(dot)kernel(dot)org, linux-kernel(at)vger(dot)kernel(dot)org, robertmhaas(at)gmail(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Improve lseek scalability v3
Date: 2011-09-19 12:31:00
Message-ID: 20110919123100.GJ12765@tamriel.snowman.net
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* Benjamin LaHaise (bcrl(at)kvack(dot)org) wrote:
> For such tables, can't Postgres track the size of the file internally? I'm
> assuming it's keeping file descriptors open on the tables it manages, in
> which case when it writes to a file to extend it, the internally stored size
> could be updated. Not making a syscall at all would scale far better than
> even a modified lseek() will perform.

We'd have to have it in shared memory and have a lock around it, it
wouldn't be cheap at all.

Thanks,

Stephen

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