Skip site navigation (1) Skip section navigation (2)

Re: Dynamic Partitioning using Segment Visibility Maps

From: "Gokulakannan Somasundaram" <gokul007(at)gmail(dot)com>
To: tomas(at)tuxteam(dot)de
Cc: "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 08:24:02
Message-ID: 9362e74e0801060024j4e6c3ee4maf189eabd3ab15b1@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Jan 6, 2008 11:27 AM, <tomas(at)tuxteam(dot)de> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> 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).


But the current index scans - Index Scan and Bitmap  Index Scan, doesn't
provide the exact benefit of partitioning, even if all the columns are
covered by the index. It does a lot more disk reads than the partitioning
scheme. I think you are looking for something like Block indexes in
Multi-dimensional Clusters in DB2.  Heikki did something like that in a more
subtle way.

Postgresql Clusters, as you may know doesn't maintain the order with
inserts. We might go for Index Organized Tables/Clustered indexes. But then,
B-tree would give lot of performance problems, if the Index Tuple size
increases beyond a certain point.

Thanks,
Gokul.

In response to

pgsql-hackers by date

Next:From: Joshua D. DrakeDate: 2008-01-06 08:40:56
Subject: Bug: Unreferenced temp tables disables vacuum to update xid
Previous:From: Gokulakannan SomasundaramDate: 2008-01-06 08:17:01
Subject: Re: Dynamic Partitioning using Segment Visibility Maps

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group