Subject: Re: On Scalability
From: Simon Riggs <simon@2ndQuadrant.com>
To: Vincenzo Romano <vincenzo.romano@notorand.it>
Cc: pgsql-hackers@postgresql.org
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Date: Thu, 07 Oct 2010 22:42:59 +0100
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On Thu, 2010-10-07 at 14:10 +0200, Vincenzo Romano wrote:

> Making these things sub-linear (whether not O(log n) or even O(1) ),
> provided that there's  way to, would make this RDBMS more appealing
> to enterprises.
> I mean also partial indexes (as an alternative to table partitioning).
> Being able to effectively cope with "a dozen child tables or so" it's more
> like an amateur feature.
> If you really need partitioning (or just hierarchical stuff) I think you'll need
> for quite more than a dozen items.
> If you partition by just weeks, you'll need 50+ a year.
> 
> Is there any precise direction to where look into the code for it?
> 
> Is there a way to put this into a wish list?

It's already on the wish list ("TODO") and has been for many years.

We've mostly lacked somebody with the experience and time/funding to
complete that implementation work. I figure I'll be doing it for 9.2
now; it may be difficult to do this for next release.

Theoretically, this can be O(n.log n) for range partitioning and O(1)
for exact value partitioning, though the latter isn't a frequent use
case.

Your conclusion that the current partitioning only works with a dozen or
so items doesn't match the experience of current users however.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Development, 24x7 Support, Training and Services