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Re: Dynamic Partitioning using Segment Visibility Maps

From: tomas(at)tuxteam(dot)de
To: Gokulakannan Somasundaram <gokul007(at)gmail(dot)com>
Cc: tomas(at)tuxteam(dot)de, Simon Riggs <simon(at)2ndquadrant(dot)com>,Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>,pgsql-hackers(at)postgresql(dot)org,Markus Schiltknecht <markus(at)bluegap(dot)ch>,Andrew Sullivan <ajs(at)crankycanuck(dot)ca>
Subject: Re: Dynamic Partitioning using Segment Visibility Maps
Date: 2008-01-06 05:57:36
Message-ID: 20080106055736.GB32629@www.trapp.net (view raw or flat)
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On Sun, Jan 06, 2008 at 01:12:32AM +0530, Gokulakannan Somasundaram wrote:
> On Jan 5, 2008 6:15 PM, <tomas(at)tuxteam(dot)de> wrote:
> 
> >
> > One thought I had back then, with partitioned tables was "gee -- B-tree
> > index is already doing a partition; why do a manual partition on top of
> > that?".

> Can you please explain more on what you are trying to say here?

Sure. A B-tree is just a device to partition something along some order.
If you have , say, a table of orders (to use the example upthread) and a
B-tree index on order date, this index partitions your set (at
recursively finer levels). Of course, you'd have to "sort" your data
alogn this index, but PostgreSQL knows how to do this trick: CLUSTER.

This was just a vague idea, many things were missing (for example to
separate out the more quiescent parts of the table into their own files)
which are spelled out in Simon Riggs' proposal.

This struck me when seeing people partition tables by hand -- and I was
delighted to actually watch Simon forging a real design.

Regards
- -- tomás
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