From: Ron Mayer <rm_pg@cheapcomplexdevices.com>
To: Luke Lonergan <llonergan@greenplum.com>
Subject: Re: Large tables (was: RAID 0 not as fast as
Date: Sun, 24 Sep 2006 06:29:50 -0700
Message-ID: <4516884E.6070308@cheapcomplexdevices.com> (raw)
In-Reply-To: <C138AAB1.2524%llonergan@greenplum.com>
References: <20060922034037.GB2820@mark.mielke.cc>
<C138AAB1.2524%llonergan@greenplum.com>
Luke Lonergan wrote:
>
> I think the topic is similar to "cache bypass", used in cache capable vector
> processors (Cray, Convex, Multiflow, etc) in the 90's. When you are
> scanning through something larger than the cache, it should be marked
> "non-cacheable" and bypass caching altogether. This avoids a copy, and
> keeps the cache available for things that can benefit from it.
And 'course some file systems do this automatically when they
detect a sequential scan[1] though it can have unexpected (to some)
negative side effects[2]. For file systems that support freebehind
as a configurable parameter, it might be easier to experiment with
the idea there.
[1] http://www.ediaudit.com/doc_sol10/Solaris_10_Doc/common/SUNWaadm/reloc/sun_docs/C/solaris_10/SUNWaad...
[2] http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6207772
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To: pgsql-performance@postgresql.org
Cc: rm_pg@cheapcomplexdevices.com, llonergan@greenplum.com
Subject: Re: Large tables (was: RAID 0 not as fast as
In-Reply-To: <4516884E.6070308@cheapcomplexdevices.com>
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