Re: On the usefulness of hint bits

From: Leonardo Francalanci <m_lists(at)yahoo(dot)it>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: On the usefulness of hint bits
Date: 2010-10-11 15:03:03
Message-ID: 138488.88457.qm@web29005.mail.ird.yahoo.com
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> Reduction of contention for pg_clog access, for one thing. If you read
> the archives, you'll find that pg_clog access contention has been shown
> to be one cause of "context swap storms". Having to go to clog for
> every single tuple access would make that orders of magnitude worse.

Ok; is it the

"Wierd context-switching issue on Xeon"

thread? Or that has nothing to do with it? I tried "context swap storms
pg_clog" but I didn't get anything...

> More generally, we're not going to give up hint bits even if there are
> identifiable workloads where they don't buy much --- because there are
> many others where they do.

Sure: I wasn't suggesting to give up them, just to make their usage
"user selectable" (and "on" by default)

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