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jung1975
Aged Yak Warrior
503 Posts |
 Posted - 2004-04-22 : 18:22:27
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| Does anyone have a list of datawarehousing /Business intelligence interview questions? or can share the Data warehousing/BI interview experience with me?Thanks |
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MichaelP
Jedi Yak
2489 Posts |
Posted - 2004-04-22 : 18:32:37
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| Explain the difference between Snowflake and Star Schema.Why are OLTP database designs not generally a good idea for a Data Warehouse?Why should you put your data warehouse on a different system than your OLTP system?Explain the advanatages of RAID 1, 1/0, and 5. What type of RAID setup would you put your TX logs? What setup for your data?That should get things started.Michael<Yoda>Use the Search page you must. Find the answer you will.</Yoda> |
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Joozh
Posting Yak Master
145 Posts |
Posted - 2004-04-23 : 00:06:25
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| Hi Michael,I know this will be a botheration but against each of these (these all are excellent questions), can you kindly provide a brief answer. I'm not preparing for an interview but your reply will really help me strengthen my concetps and I am sure that it will also give me new tips.Many thanks in advance.Thanks & Regards.-J |
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X002548
Not Just a Number
15586 Posts |
Posted - 2004-04-23 : 12:18:21
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| You can certainly google up some info...See...http://datawarehouse.dci.com/articles/1998/07/28star.htmDamn...I've got to build a damn warehouse one of these days with the sql server tools...We built before they were called that....now they got all of these buzz words...I gotta be able to pass the buzz word interview...Brett8-) |
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Joozh
Posting Yak Master
145 Posts |
Posted - 2004-04-26 : 23:50:34
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| Thanks for the article. May I request if I can get answers to the following questions too. Sorry for the botheration and many thanks in advance:1) Why are OLTP database designs not generally a good idea for a Data Warehouse?2) Why should you put your data warehouse on a different system than your OLTP system?3) * * Explain the advanatages of RAID 1, 1/0, and 5. What type of RAID setup would you put your TX logs? What setup for your data?Thanks & Regards.-J |
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derrickleggett
Pointy Haired Yak DBA
4184 Posts |
Posted - 2004-04-27 : 00:20:54
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| 1) Why are OLTP database designs not generally a good idea for a Data Warehouse?OLTP databases are normalized structure designed to reduce data, increase performance of transactions, and decrease overall reads/writes. When you are wanting to build summaries and cube analysis blocks of things, pulling this from a highly normalized transaction based structure creates huge amounts of overhead, is slow, and is inefficient.2) Why should you put your data warehouse on a different system than your OLTP system?There are a log of reasons. OLTP is designed to serve real-time transactional business needs. The idea is get in/get out quickly and efficiently. OLAP is designed to have large batch windows that aggregate and summarize data into reporting schemas. The two are dynamically opposed. The processing of the OLAP portion of the database kills the processing and memory utilization needed to keep the OLTP system active and "lively". The OLAP system also interferes with the data as it's locking and causing contention on data as it's creating the aggregate views that are needed.The list for this goes on and on and on and on. They are two vastly different types of systems though. The resources will interefere with each other and end up choking your entire system to death.3) * * Explain the advanatages of RAID 1, 1/0, and 5. What type of RAID setup would you put your TX logs? What setup for your data?Transaction logs write sequentially and don't need to be read at all. The ideal is to have each on RAID 1/0 because it has much better write performance than RAID 5. RAID 1 is also better for TX logs and costs less than 1/0 to implement. It has a tad less reliability and performance is a little worse generally speaking.RAID 5 is best for data generally because of cost and the fact it provides great read capability. Check this site out. It's a great beginners tutorial on RAID:http://www.acnc.com/04_00.htmlMeanOldDBAderrickleggett@hotmail.comWhen life gives you a lemon, fire the DBA. |
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Joozh
Posting Yak Master
145 Posts |
Posted - 2004-04-27 : 02:57:27
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| Many thanks derrickleggett. Appreciate your reply :-)Thanks & Regards.-J |
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jerryvn01
Starting Member
3 Posts |
Posted - 2010-07-03 : 13:08:20
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| spam removed |
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anbetophillip
Starting Member
1 Post |
Posted - 2010-07-15 : 05:39:27
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| spam removed |
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X002548
Not Just a Number
15586 Posts |
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patricholier
Starting Member
3 Posts |
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nigelrivett
Master Smack Fu Yak Hacker
3385 Posts |
Posted - 2011-06-09 : 08:11:47
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| >> RAID 5 is best for data generally because of cost and the fact it provides great read capability. Ummm what about write performance?==========================================Cursors are useful if you don't know sql.SSIS can be used in a similar way.Beer is not cold and it isn't fizzy. |
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Michael Valentine Jones
Yak DBA Kernel (pronounced Colonel)
7020 Posts |
Posted - 2011-06-09 : 09:22:13
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quote:
Originally posted by nigelrivett
>> RAID 5 is best for data generally because of cost and the fact it provides great read capability. Ummm what about write performance?==========================================Cursors are useful if you don't know sql.SSIS can be used in a similar way.Beer is not cold and it isn't fizzy.
Seven year old thread.I don't think Derrick has posted on SQL Team for over four years.CODO ERGO SUM |
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hambim336
Starting Member
6 Posts |
Posted - 2011-08-30 : 05:17:56
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| HiYou can find this info by using search box in the top of website with some keywords related before posting questions. |
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hambim336
Starting Member
6 Posts |
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hambim336
Starting Member
6 Posts |
Posted - 2011-11-30 : 03:09:30
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| HiThis topic help me a lot in developing my project. I will contribute more when I finished it. |
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hambim336
Starting Member
6 Posts |
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soriana
Starting Member
1 Post |
Posted - 2014-05-18 : 11:04:29
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| You may find some helpful information here: [http://sorianaops.wordpress.com/] |
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dataonfocus
Starting Member
1 Post |
Posted - 2015-01-12 : 07:50:52
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| I think you should know the answers to the basic questions related to OLAP, OLAP cubes, Data Mart, etc.Then you should investigate about schemas: Star, Snowflake, and others.Database knowledge is absolutely critical too!More information on [url]http://www.dataonfocus.com/data-warehouse-interview-questions-and-answers/[/url] |
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Data warehousing/BI interview questions