topic Re: query in RDBMS in Operating System - HP-UX

query in RDBMS

bbbnnn — Thu, 16 Feb 2006 04:24:23 GMT

What is the use of adding duplication in the tables,inturn that may increase the size and becomes large

Cheers
Priya

Re: query in RDBMS

Muthukumar_5 — Thu, 16 Feb 2006 04:29:07 GMT

Duplicates are getting added bcas of poor database design. If an unique employee is wanted to two address and having only one column of address. Then we have to add another address in separate entry.

Duplication is not a needy effect in DB.

--
Muthu

Re: query in RDBMS

Arunvijai_4 — Thu, 16 Feb 2006 04:30:45 GMT

Hi priya,

This may be helpful to you,

http://www.dba-oracle.com/art_9i_denormal.htm

-Arun

Re: query in RDBMS

Sanjay Kumar Suri — Thu, 16 Feb 2006 04:52:00 GMT

Can you rephrase your question?

Additing duplicate records could be by design. Can be avoided by introducing primary key or unique key index.

Check this link as well:

http://www.orafaq.com/faqdesgn.htm

sks

Re: query in RDBMS

Yogeeraj_1 — Thu, 16 Feb 2006 05:00:41 GMT

hi priya,

duplication = redundancy

this is very common when building data warehouses. Since they data almost never changes, you can afford to allow duplicates that would not hinder the integrity of the data.

hope this helps!

kind regards
yogeeraj

Re: query in RDBMS

Yogeeraj_1 — Thu, 16 Feb 2006 05:03:57 GMT

hi again,

below a few characteristics of data warehouses:

o hundreds of gigabytes to terabyte in size. dealing with that scale takes knowledge.

o periods of read mostly activity, with periods of short bursts of FURIOUS load, reorganisation and rebuild activity

o use of specialised features that many people have read about but fewer have used such as bitmap indexes, materialized views, star query schemas, partitioning, etc.

o use of parallel query -- similar to above.

o constantly shifting set of questions - requiring shifting sets of data, MV's, indexes, etc (most systems, once production, are relatively static. DW's -- every day is a brand new day)

To name a few. Dealing with terabytes of data is hard, takes experience. It also require lots of know-how.

hope this helps too!

kind regards
yogeeraj