[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message]

Re: Why not reinvent the wheel?

  • From: Vasileios Papadimos <vpapad@c...>
  • To: Joe English <jenglish@f...>
  • Date: Fri, 02 Mar 2001 18:27:13 -0800

Re: Why not reinvent the wheel?
On Fri, Mar 02, 2001 at 01:02:48PM -0800, Joe English wrote:

> Ordered and unordered joins are both associative, in the sense that:
> 
>     [(x1,x2,x3) | x1 <- e1, (x2,x3) <- [(x2,x3) | x2 <- e2, x3 <- e3]]
> ==
>     [(x1,x2,x3) | (x1,x2) <- [(x1,x2) | x1 <- e1, x2 <- e2], x3 <- e3]
> 
> 
> Unordered joins however are commutative:

Of course Joe is right! Commutativity is what we gain from "unordering" 
(disordering!?) joins. Commutativity + associativity makes for the 
exponential search space in join optimization. 

Regards,

Vassilis Papadimos.

PURCHASE STYLUS STUDIO ONLINE TODAY!

Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced!

Buy Stylus Studio Now

Download The World's Best XML IDE!

Accelerate XML development with our award-winning XML IDE - Download a free trial today!

Don't miss another message! Subscribe to this list today.
Email
First Name
Last Name
Company
Subscribe in XML format
RSS 2.0
Atom 0.3
 

Stylus Studio has published XML-DEV in RSS and ATOM formats, enabling users to easily subcribe to the list from their preferred news reader application.


Stylus Studio Sponsored Links are added links designed to provide related and additional information to the visitors of this website. they were not included by the author in the initial post. To view the content without the Sponsor Links please click here.

Site Map | Privacy Policy | Terms of Use | Trademarks
Free Stylus Studio XML Training:
W3C Member
Stylus Studio® and DataDirect XQuery ™are products from DataDirect Technologies, is a registered trademark of Progress Software Corporation, in the U.S. and other countries. © 2004-2013 All Rights Reserved.