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Re: Dynamic Partitioning using Segment Visibility Maps

From: Csaba Nagy <nagy(at)ecircle-ag(dot)com>
To: Markus Schiltknecht <markus(at)bluegap(dot)ch>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Dynamic Partitioning using Segment Visibility Maps
Date: 2008-01-07 13:32:03
Message-ID: 1199712723.5646.14.camel@PCD12478 (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, 2008-01-07 at 14:20 +0100, Markus Schiltknecht wrote:
> Why is that? AFAIUI, Segment Exclusion combines perfectly well with 
> clustering. Or even better, with an upcoming feature to maintain 
> clustered ordering. Where do you see disadvantages such an optimization 
> for sequential scans?

Well, as I understood it, this would be some kind of special case of
clustering, where the cluster key is expected to be ever increasing in
time and new rows would not be randomly distributed over the complete
possible range. In theory you could also have each segment in turn be
clustered on some other criteria than the partitioning criteria so
indexed access could also be better on the main selection criteria which
could be different than the partitioning criteria. All this is of course
just speculations - but I guess that's what you expected too in this
discussion :-)

Cheers,
Csaba.



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