Solved

Estimating size of tuples

Posted on 2011-09-04
6
367 Views
Last Modified: 2012-05-12
If I have to estimate a size of tuples. Would I multiply them together? I am unsure how to approach this as I believe I would multiply them up. What strategy would you take with this? Thanks!

R1 has 1000, r2 has 1500, and r3 has 750
0
Comment
Question by:Rowley4
  • 3
  • 2
6 Comments
 
LVL 51

Expert Comment

by:HainKurt
ID: 36481799
can you please explain what you are trying to do
0
 

Author Comment

by:Rowley4
ID: 36481810
Say r1 (ABC, r2 (CDE) and r3 (EF) with primary keys A C and E. I wanted to estimate the sizes of these tuples if r1 has 1000 r2 has 1500 and r3 has 750?
0
 
LVL 51

Expert Comment

by:HainKurt
ID: 36481819
can ask more :) until somebody else answer your question

what is R1, R2, R3
are those tables? ABC, CDE, EF are columns? A C E are PK on each table?
R1 has 1000 means it has 1000 records (1000 unique A value)?

by tuple what do you mean, can you give samples...
0
U.S. Department of Agriculture and Acronis Access

With the new era of mobile computing, smartphones and tablets, wireless communications and cloud services, the USDA sought to take advantage of a mobilized workforce and the blurring lines between personal and corporate computing resources.

 

Author Comment

by:Rowley4
ID: 36481958
Yes, you are exactly correct on all your assumptions.

Suppose we have
R(a,b) with T(R) = 1000 and V(R,b) = 20
S(b,c) with T(S) = 2000, V(S,b) = 50, and V(S,c) = 100
U(c,d) with T(U) = 5000 and V(U,c) = 500
What is the estimated size of R    S    U?
First join R and S (on attribute b):
estimated size of result, X, is T(R)*T(S)/max(V(R,b),V(S,b)) = 40,000
by containment of value sets, number of values of c in X is the same as in S, namely 100
Then join X with U (on attribute c):
estimated size of result is T(X)*T(U)/max(V(X,c),V(U,c)) = 400,000
0
 
LVL 51

Expert Comment

by:HainKurt
ID: 36482563
I am totally lost :)
0
 
LVL 83

Accepted Solution

by:
Dave Baldwin earned 500 total points
ID: 36482661
Courtesy of 'paulsauve' on another question, from this page http://www.deeptraining.com/litwin/dbdesign/FundamentalsOfRelationalDatabaseDesign.aspx  :

"In fact, Codd (and other relational database theorists) use the terms relations, attributes and tuples where most of us use the more common terms tables, columns and rows, respectively (or the more physical—and thus less preferable for discussions of database design theory—files, fields and records)."

I just saw this about 5 minutes ago.  Til then I didn't know what 'tuples' were about either.  I don't know that it will help to answer this question because I believe too of what @Rowley4 is saying is still undefined.  If he is trying to find out how storage is required, the answer is simply the number of rows times the average or estimated size of the data.
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Popularity Can Be Measured Sometimes we deal with questions of popularity, and we need a way to collect opinions from our clients.  This article shows a simple teaching example of how we might elect a favorite color by letting our clients vote for …
Does the idea of dealing with bits scare or confuse you? Does it seem like a waste of time in an age where we all have terabytes of storage? If so, you're missing out on one of the core tools in every professional programmer's toolbox. Learn how to …
This demo shows you how to set up the containerized NetScaler CPX with NetScaler Management and Analytics System in a non-routable Mesos/Marathon environment for use with Micro-Services applications.
This tutorial demonstrates a quick way of adding group price to multiple Magento products.

919 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

17 Experts available now in Live!

Get 1:1 Help Now